/* * Copyright (c) 1994,1997 John S. Dyson * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice immediately at the beginning of the file, without modification, * this list of conditions, and the following disclaimer. * 2. Absolutely no warranty of function or purpose is made by the author * John S. Dyson. * * $FreeBSD: src/sys/kern/vfs_bio.c,v 1.242.2.20 2003/05/28 18:38:10 alc Exp $ * $DragonFly: src/sys/kern/vfs_bio.c,v 1.75 2006/05/07 00:24:02 dillon Exp $ */ /* * this file contains a new buffer I/O scheme implementing a coherent * VM object and buffer cache scheme. Pains have been taken to make * sure that the performance degradation associated with schemes such * as this is not realized. * * Author: John S. Dyson * Significant help during the development and debugging phases * had been provided by David Greenman, also of the FreeBSD core team. * * see man buf(9) for more info. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Buffer queues. */ #define BUFFER_QUEUES 6 enum bufq_type { BQUEUE_NONE, /* not on any queue */ BQUEUE_LOCKED, /* locked buffers */ BQUEUE_CLEAN, /* non-B_DELWRI buffers */ BQUEUE_DIRTY, /* B_DELWRI buffers */ BQUEUE_EMPTYKVA, /* empty buffer headers with KVA assignment */ BQUEUE_EMPTY /* empty buffer headers */ }; TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES]; static MALLOC_DEFINE(M_BIOBUF, "BIO buffer", "BIO buffer"); struct bio_ops bioops; /* I/O operation notification */ struct buf *buf; /* buffer header pool */ static void vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to); static void vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to); static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m); static void vfs_clean_pages(struct buf *bp); static void vfs_setdirty(struct buf *bp); static void vfs_vmio_release(struct buf *bp); static int flushbufqueues(void); static int bd_request; static void buf_daemon (void); /* * bogus page -- for I/O to/from partially complete buffers * this is a temporary solution to the problem, but it is not * really that bad. it would be better to split the buffer * for input in the case of buffers partially already in memory, * but the code is intricate enough already. */ vm_page_t bogus_page; int runningbufspace; static int bufspace, maxbufspace, bufmallocspace, maxbufmallocspace, lobufspace, hibufspace; static int bufreusecnt, bufdefragcnt, buffreekvacnt; static int needsbuffer; static int lorunningspace, hirunningspace, runningbufreq; static int numdirtybuffers, lodirtybuffers, hidirtybuffers; static int numfreebuffers, lofreebuffers, hifreebuffers; static int getnewbufcalls; static int getnewbufrestarts; /* * Sysctls for operational control of the buffer cache. */ SYSCTL_INT(_vfs, OID_AUTO, lodirtybuffers, CTLFLAG_RW, &lodirtybuffers, 0, "Number of dirty buffers to flush before bufdaemon becomes inactive"); SYSCTL_INT(_vfs, OID_AUTO, hidirtybuffers, CTLFLAG_RW, &hidirtybuffers, 0, "High watermark used to trigger explicit flushing of dirty buffers"); SYSCTL_INT(_vfs, OID_AUTO, lofreebuffers, CTLFLAG_RW, &lofreebuffers, 0, "Low watermark for special reserve in low-memory situations"); SYSCTL_INT(_vfs, OID_AUTO, hifreebuffers, CTLFLAG_RW, &hifreebuffers, 0, "High watermark for special reserve in low-memory situations"); SYSCTL_INT(_vfs, OID_AUTO, lorunningspace, CTLFLAG_RW, &lorunningspace, 0, "Minimum amount of buffer space required for active I/O"); SYSCTL_INT(_vfs, OID_AUTO, hirunningspace, CTLFLAG_RW, &hirunningspace, 0, "Maximum amount of buffer space to usable for active I/O"); /* * Sysctls determining current state of the buffer cache. */ SYSCTL_INT(_vfs, OID_AUTO, numdirtybuffers, CTLFLAG_RD, &numdirtybuffers, 0, "Pending number of dirty buffers"); SYSCTL_INT(_vfs, OID_AUTO, numfreebuffers, CTLFLAG_RD, &numfreebuffers, 0, "Number of free buffers on the buffer cache free list"); SYSCTL_INT(_vfs, OID_AUTO, runningbufspace, CTLFLAG_RD, &runningbufspace, 0, "I/O bytes currently in progress due to asynchronous writes"); SYSCTL_INT(_vfs, OID_AUTO, maxbufspace, CTLFLAG_RD, &maxbufspace, 0, "Hard limit on maximum amount of memory usable for buffer space"); SYSCTL_INT(_vfs, OID_AUTO, hibufspace, CTLFLAG_RD, &hibufspace, 0, "Soft limit on maximum amount of memory usable for buffer space"); SYSCTL_INT(_vfs, OID_AUTO, lobufspace, CTLFLAG_RD, &lobufspace, 0, "Minimum amount of memory to reserve for system buffer space"); SYSCTL_INT(_vfs, OID_AUTO, bufspace, CTLFLAG_RD, &bufspace, 0, "Amount of memory available for buffers"); SYSCTL_INT(_vfs, OID_AUTO, maxmallocbufspace, CTLFLAG_RD, &maxbufmallocspace, 0, "Maximum amount of memory reserved for buffers using malloc"); SYSCTL_INT(_vfs, OID_AUTO, bufmallocspace, CTLFLAG_RD, &bufmallocspace, 0, "Amount of memory left for buffers using malloc-scheme"); SYSCTL_INT(_vfs, OID_AUTO, getnewbufcalls, CTLFLAG_RD, &getnewbufcalls, 0, "New buffer header acquisition requests"); SYSCTL_INT(_vfs, OID_AUTO, getnewbufrestarts, CTLFLAG_RD, &getnewbufrestarts, 0, "New buffer header acquisition restarts"); SYSCTL_INT(_vfs, OID_AUTO, bufdefragcnt, CTLFLAG_RD, &bufdefragcnt, 0, "Buffer acquisition restarts due to fragmented buffer map"); SYSCTL_INT(_vfs, OID_AUTO, buffreekvacnt, CTLFLAG_RD, &buffreekvacnt, 0, "Amount of time KVA space was deallocated in an arbitrary buffer"); SYSCTL_INT(_vfs, OID_AUTO, bufreusecnt, CTLFLAG_RD, &bufreusecnt, 0, "Amount of time buffer re-use operations were successful"); SYSCTL_INT(_debug_sizeof, OID_AUTO, buf, CTLFLAG_RD, 0, sizeof(struct buf), "sizeof(struct buf)"); char *buf_wmesg = BUF_WMESG; extern int vm_swap_size; #define VFS_BIO_NEED_ANY 0x01 /* any freeable buffer */ #define VFS_BIO_NEED_DIRTYFLUSH 0x02 /* waiting for dirty buffer flush */ #define VFS_BIO_NEED_FREE 0x04 /* wait for free bufs, hi hysteresis */ #define VFS_BIO_NEED_BUFSPACE 0x08 /* wait for buf space, lo hysteresis */ /* * numdirtywakeup: * * If someone is blocked due to there being too many dirty buffers, * and numdirtybuffers is now reasonable, wake them up. */ static __inline void numdirtywakeup(int level) { if (numdirtybuffers <= level) { if (needsbuffer & VFS_BIO_NEED_DIRTYFLUSH) { needsbuffer &= ~VFS_BIO_NEED_DIRTYFLUSH; wakeup(&needsbuffer); } } } /* * bufspacewakeup: * * Called when buffer space is potentially available for recovery. * getnewbuf() will block on this flag when it is unable to free * sufficient buffer space. Buffer space becomes recoverable when * bp's get placed back in the queues. */ static __inline void bufspacewakeup(void) { /* * If someone is waiting for BUF space, wake them up. Even * though we haven't freed the kva space yet, the waiting * process will be able to now. */ if (needsbuffer & VFS_BIO_NEED_BUFSPACE) { needsbuffer &= ~VFS_BIO_NEED_BUFSPACE; wakeup(&needsbuffer); } } /* * runningbufwakeup: * * Accounting for I/O in progress. * */ static __inline void runningbufwakeup(struct buf *bp) { if (bp->b_runningbufspace) { runningbufspace -= bp->b_runningbufspace; bp->b_runningbufspace = 0; if (runningbufreq && runningbufspace <= lorunningspace) { runningbufreq = 0; wakeup(&runningbufreq); } } } /* * bufcountwakeup: * * Called when a buffer has been added to one of the free queues to * account for the buffer and to wakeup anyone waiting for free buffers. * This typically occurs when large amounts of metadata are being handled * by the buffer cache ( else buffer space runs out first, usually ). */ static __inline void bufcountwakeup(void) { ++numfreebuffers; if (needsbuffer) { needsbuffer &= ~VFS_BIO_NEED_ANY; if (numfreebuffers >= hifreebuffers) needsbuffer &= ~VFS_BIO_NEED_FREE; wakeup(&needsbuffer); } } /* * waitrunningbufspace() * * runningbufspace is a measure of the amount of I/O currently * running. This routine is used in async-write situations to * prevent creating huge backups of pending writes to a device. * Only asynchronous writes are governed by this function. * * Reads will adjust runningbufspace, but will not block based on it. * The read load has a side effect of reducing the allowed write load. * * This does NOT turn an async write into a sync write. It waits * for earlier writes to complete and generally returns before the * caller's write has reached the device. */ static __inline void waitrunningbufspace(void) { if (runningbufspace > hirunningspace) { crit_enter(); while (runningbufspace > hirunningspace) { ++runningbufreq; tsleep(&runningbufreq, 0, "wdrain", 0); } crit_exit(); } } /* * vfs_buf_test_cache: * * Called when a buffer is extended. This function clears the B_CACHE * bit if the newly extended portion of the buffer does not contain * valid data. */ static __inline__ void vfs_buf_test_cache(struct buf *bp, vm_ooffset_t foff, vm_offset_t off, vm_offset_t size, vm_page_t m) { if (bp->b_flags & B_CACHE) { int base = (foff + off) & PAGE_MASK; if (vm_page_is_valid(m, base, size) == 0) bp->b_flags &= ~B_CACHE; } } /* * bd_wakeup: * * Wake up the buffer daemon if the number of outstanding dirty buffers * is above specified threshold 'dirtybuflevel'. * * The buffer daemon is explicitly woken up when (a) the pending number * of dirty buffers exceeds the recovery and stall mid-point value, * (b) during bwillwrite() or (c) buf freelist was exhausted. */ static __inline__ void bd_wakeup(int dirtybuflevel) { if (bd_request == 0 && numdirtybuffers >= dirtybuflevel) { bd_request = 1; wakeup(&bd_request); } } /* * bd_speedup: * * Speed up the buffer cache flushing process. */ static __inline__ void bd_speedup(void) { bd_wakeup(1); } /* * bufinit: * * Load time initialisation of the buffer cache, called from machine * dependant initialization code. */ void bufinit(void) { struct buf *bp; vm_offset_t bogus_offset; int i; /* next, make a null set of free lists */ for (i = 0; i < BUFFER_QUEUES; i++) TAILQ_INIT(&bufqueues[i]); /* finally, initialize each buffer header and stick on empty q */ for (i = 0; i < nbuf; i++) { bp = &buf[i]; bzero(bp, sizeof *bp); bp->b_flags = B_INVAL; /* we're just an empty header */ bp->b_cmd = BUF_CMD_DONE; bp->b_qindex = BQUEUE_EMPTY; initbufbio(bp); xio_init(&bp->b_xio); LIST_INIT(&bp->b_dep); BUF_LOCKINIT(bp); TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_EMPTY], bp, b_freelist); } /* * maxbufspace is the absolute maximum amount of buffer space we are * allowed to reserve in KVM and in real terms. The absolute maximum * is nominally used by buf_daemon. hibufspace is the nominal maximum * used by most other processes. The differential is required to * ensure that buf_daemon is able to run when other processes might * be blocked waiting for buffer space. * * maxbufspace is based on BKVASIZE. Allocating buffers larger then * this may result in KVM fragmentation which is not handled optimally * by the system. */ maxbufspace = nbuf * BKVASIZE; hibufspace = imax(3 * maxbufspace / 4, maxbufspace - MAXBSIZE * 10); lobufspace = hibufspace - MAXBSIZE; lorunningspace = 512 * 1024; hirunningspace = 1024 * 1024; /* * Limit the amount of malloc memory since it is wired permanently into * the kernel space. Even though this is accounted for in the buffer * allocation, we don't want the malloced region to grow uncontrolled. * The malloc scheme improves memory utilization significantly on average * (small) directories. */ maxbufmallocspace = hibufspace / 20; /* * Reduce the chance of a deadlock occuring by limiting the number * of delayed-write dirty buffers we allow to stack up. */ hidirtybuffers = nbuf / 4 + 20; numdirtybuffers = 0; /* * To support extreme low-memory systems, make sure hidirtybuffers cannot * eat up all available buffer space. This occurs when our minimum cannot * be met. We try to size hidirtybuffers to 3/4 our buffer space assuming * BKVASIZE'd (8K) buffers. */ while (hidirtybuffers * BKVASIZE > 3 * hibufspace / 4) { hidirtybuffers >>= 1; } lodirtybuffers = hidirtybuffers / 2; /* * Try to keep the number of free buffers in the specified range, * and give special processes (e.g. like buf_daemon) access to an * emergency reserve. */ lofreebuffers = nbuf / 18 + 5; hifreebuffers = 2 * lofreebuffers; numfreebuffers = nbuf; /* * Maximum number of async ops initiated per buf_daemon loop. This is * somewhat of a hack at the moment, we really need to limit ourselves * based on the number of bytes of I/O in-transit that were initiated * from buf_daemon. */ bogus_offset = kmem_alloc_pageable(kernel_map, PAGE_SIZE); bogus_page = vm_page_alloc(kernel_object, ((bogus_offset - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), VM_ALLOC_NORMAL); vmstats.v_wire_count++; } /* * Initialize the embedded bio structures */ void initbufbio(struct buf *bp) { bp->b_bio1.bio_buf = bp; bp->b_bio1.bio_prev = NULL; bp->b_bio1.bio_offset = NOOFFSET; bp->b_bio1.bio_next = &bp->b_bio2; bp->b_bio1.bio_done = NULL; bp->b_bio2.bio_buf = bp; bp->b_bio2.bio_prev = &bp->b_bio1; bp->b_bio2.bio_offset = NOOFFSET; bp->b_bio2.bio_next = NULL; bp->b_bio2.bio_done = NULL; } /* * Reinitialize the embedded bio structures as well as any additional * translation cache layers. */ void reinitbufbio(struct buf *bp) { struct bio *bio; for (bio = &bp->b_bio1; bio; bio = bio->bio_next) { bio->bio_done = NULL; bio->bio_offset = NOOFFSET; } } /* * Push another BIO layer onto an existing BIO and return it. The new * BIO layer may already exist, holding cached translation data. */ struct bio * push_bio(struct bio *bio) { struct bio *nbio; if ((nbio = bio->bio_next) == NULL) { int index = bio - &bio->bio_buf->b_bio_array[0]; if (index >= NBUF_BIO) { panic("push_bio: too many layers bp %p\n", bio->bio_buf); } nbio = &bio->bio_buf->b_bio_array[index + 1]; bio->bio_next = nbio; nbio->bio_prev = bio; nbio->bio_buf = bio->bio_buf; nbio->bio_offset = NOOFFSET; nbio->bio_done = NULL; nbio->bio_next = NULL; } KKASSERT(nbio->bio_done == NULL); return(nbio); } void pop_bio(struct bio *bio) { /* NOP */ } void clearbiocache(struct bio *bio) { while (bio) { bio->bio_offset = NOOFFSET; bio = bio->bio_next; } } /* * bfreekva: * * Free the KVA allocation for buffer 'bp'. * * Must be called from a critical section as this is the only locking for * buffer_map. * * Since this call frees up buffer space, we call bufspacewakeup(). */ static void bfreekva(struct buf *bp) { int count; if (bp->b_kvasize) { ++buffreekvacnt; count = vm_map_entry_reserve(MAP_RESERVE_COUNT); vm_map_lock(buffer_map); bufspace -= bp->b_kvasize; vm_map_delete(buffer_map, (vm_offset_t) bp->b_kvabase, (vm_offset_t) bp->b_kvabase + bp->b_kvasize, &count ); vm_map_unlock(buffer_map); vm_map_entry_release(count); bp->b_kvasize = 0; bufspacewakeup(); } } /* * bremfree: * * Remove the buffer from the appropriate free list. */ void bremfree(struct buf *bp) { int old_qindex; crit_enter(); old_qindex = bp->b_qindex; if (bp->b_qindex != BQUEUE_NONE) { KASSERT(BUF_REFCNTNB(bp) == 1, ("bremfree: bp %p not locked",bp)); TAILQ_REMOVE(&bufqueues[bp->b_qindex], bp, b_freelist); bp->b_qindex = BQUEUE_NONE; } else { if (BUF_REFCNTNB(bp) <= 1) panic("bremfree: removing a buffer not on a queue"); } /* * Fixup numfreebuffers count. If the buffer is invalid or not * delayed-write, and it was on the EMPTY, LRU, or AGE queues, * the buffer was free and we must decrement numfreebuffers. */ if ((bp->b_flags & B_INVAL) || (bp->b_flags & B_DELWRI) == 0) { switch(old_qindex) { case BQUEUE_DIRTY: case BQUEUE_CLEAN: case BQUEUE_EMPTY: case BQUEUE_EMPTYKVA: --numfreebuffers; break; default: break; } } crit_exit(); } /* * bread: * * Get a buffer with the specified data. Look in the cache first. We * must clear B_ERROR and B_INVAL prior to initiating I/O. If B_CACHE * is set, the buffer is valid and we do not have to do anything ( see * getblk() ). */ int bread(struct vnode *vp, off_t loffset, int size, struct buf **bpp) { struct buf *bp; bp = getblk(vp, loffset, size, 0, 0); *bpp = bp; /* if not found in cache, do some I/O */ if ((bp->b_flags & B_CACHE) == 0) { KASSERT(!(bp->b_flags & B_ASYNC), ("bread: illegal async bp %p", bp)); bp->b_flags &= ~(B_ERROR | B_INVAL); bp->b_cmd = BUF_CMD_READ; vfs_busy_pages(vp, bp); vn_strategy(vp, &bp->b_bio1); return (biowait(bp)); } return (0); } /* * breadn: * * Operates like bread, but also starts asynchronous I/O on * read-ahead blocks. We must clear B_ERROR and B_INVAL prior * to initiating I/O . If B_CACHE is set, the buffer is valid * and we do not have to do anything. */ int breadn(struct vnode *vp, off_t loffset, int size, off_t *raoffset, int *rabsize, int cnt, struct buf **bpp) { struct buf *bp, *rabp; int i; int rv = 0, readwait = 0; *bpp = bp = getblk(vp, loffset, size, 0, 0); /* if not found in cache, do some I/O */ if ((bp->b_flags & B_CACHE) == 0) { bp->b_flags &= ~(B_ERROR | B_INVAL); bp->b_cmd = BUF_CMD_READ; vfs_busy_pages(vp, bp); vn_strategy(vp, &bp->b_bio1); ++readwait; } for (i = 0; i < cnt; i++, raoffset++, rabsize++) { if (inmem(vp, *raoffset)) continue; rabp = getblk(vp, *raoffset, *rabsize, 0, 0); if ((rabp->b_flags & B_CACHE) == 0) { rabp->b_flags |= B_ASYNC; rabp->b_flags &= ~(B_ERROR | B_INVAL); rabp->b_cmd = BUF_CMD_READ; vfs_busy_pages(vp, rabp); BUF_KERNPROC(rabp); vn_strategy(vp, &rabp->b_bio1); } else { brelse(rabp); } } if (readwait) { rv = biowait(bp); } return (rv); } /* * bwrite: * * Write, release buffer on completion. (Done by iodone * if async). Do not bother writing anything if the buffer * is invalid. * * Note that we set B_CACHE here, indicating that buffer is * fully valid and thus cacheable. This is true even of NFS * now so we set it generally. This could be set either here * or in biodone() since the I/O is synchronous. We put it * here. */ int bwrite(struct buf *bp) { int oldflags; if (bp->b_flags & B_INVAL) { brelse(bp); return (0); } oldflags = bp->b_flags; if (BUF_REFCNTNB(bp) == 0) panic("bwrite: buffer is not busy???"); crit_enter(); /* Mark the buffer clean */ bundirty(bp); bp->b_flags &= ~B_ERROR; bp->b_flags |= B_CACHE; bp->b_cmd = BUF_CMD_WRITE; vfs_busy_pages(bp->b_vp, bp); /* * Normal bwrites pipeline writes. NOTE: b_bufsize is only * valid for vnode-backed buffers. */ bp->b_runningbufspace = bp->b_bufsize; runningbufspace += bp->b_runningbufspace; crit_exit(); if (oldflags & B_ASYNC) BUF_KERNPROC(bp); vn_strategy(bp->b_vp, &bp->b_bio1); if ((oldflags & B_ASYNC) == 0) { int rtval = biowait(bp); brelse(bp); return (rtval); } else if ((oldflags & B_NOWDRAIN) == 0) { /* * don't allow the async write to saturate the I/O * system. Deadlocks can occur only if a device strategy * routine (like in VN) turns around and issues another * high-level write, in which case B_NOWDRAIN is expected * to be set. Otherwise we will not deadlock here because * we are blocking waiting for I/O that is already in-progress * to complete. */ waitrunningbufspace(); } return (0); } /* * bdwrite: * * Delayed write. (Buffer is marked dirty). Do not bother writing * anything if the buffer is marked invalid. * * Note that since the buffer must be completely valid, we can safely * set B_CACHE. In fact, we have to set B_CACHE here rather then in * biodone() in order to prevent getblk from writing the buffer * out synchronously. */ void bdwrite(struct buf *bp) { if (BUF_REFCNTNB(bp) == 0) panic("bdwrite: buffer is not busy"); if (bp->b_flags & B_INVAL) { brelse(bp); return; } bdirty(bp); /* * Set B_CACHE, indicating that the buffer is fully valid. This is * true even of NFS now. */ bp->b_flags |= B_CACHE; /* * This bmap keeps the system from needing to do the bmap later, * perhaps when the system is attempting to do a sync. Since it * is likely that the indirect block -- or whatever other datastructure * that the filesystem needs is still in memory now, it is a good * thing to do this. Note also, that if the pageout daemon is * requesting a sync -- there might not be enough memory to do * the bmap then... So, this is important to do. */ if (bp->b_bio2.bio_offset == NOOFFSET) { VOP_BMAP(bp->b_vp, bp->b_loffset, NULL, &bp->b_bio2.bio_offset, NULL, NULL); } /* * Set the *dirty* buffer range based upon the VM system dirty pages. */ vfs_setdirty(bp); /* * We need to do this here to satisfy the vnode_pager and the * pageout daemon, so that it thinks that the pages have been * "cleaned". Note that since the pages are in a delayed write * buffer -- the VFS layer "will" see that the pages get written * out on the next sync, or perhaps the cluster will be completed. */ vfs_clean_pages(bp); bqrelse(bp); /* * Wakeup the buffer flushing daemon if we have a lot of dirty * buffers (midpoint between our recovery point and our stall * point). */ bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); /* * note: we cannot initiate I/O from a bdwrite even if we wanted to, * due to the softdep code. */ } /* * bdirty: * * Turn buffer into delayed write request by marking it B_DELWRI. * B_RELBUF and B_NOCACHE must be cleared. * * We reassign the buffer to itself to properly update it in the * dirty/clean lists. * * Since the buffer is not on a queue, we do not update the * numfreebuffers count. * * Must be called from a critical section. * The buffer must be on BQUEUE_NONE. */ void bdirty(struct buf *bp) { KASSERT(bp->b_qindex == BQUEUE_NONE, ("bdirty: buffer %p still on queue %d", bp, bp->b_qindex)); if (bp->b_flags & B_NOCACHE) { printf("bdirty: clearing B_NOCACHE on buf %p\n", bp); bp->b_flags &= ~B_NOCACHE; } if (bp->b_flags & B_INVAL) { printf("bdirty: warning, dirtying invalid buffer %p\n", bp); } bp->b_flags &= ~B_RELBUF; if ((bp->b_flags & B_DELWRI) == 0) { bp->b_flags |= B_DELWRI; reassignbuf(bp); ++numdirtybuffers; bd_wakeup((lodirtybuffers + hidirtybuffers) / 2); } } /* * bundirty: * * Clear B_DELWRI for buffer. * * Since the buffer is not on a queue, we do not update the numfreebuffers * count. * * Must be called from a critical section. * * The buffer is typically on BQUEUE_NONE but there is one case in * brelse() that calls this function after placing the buffer on * a different queue. */ void bundirty(struct buf *bp) { if (bp->b_flags & B_DELWRI) { bp->b_flags &= ~B_DELWRI; reassignbuf(bp); --numdirtybuffers; numdirtywakeup(lodirtybuffers); } /* * Since it is now being written, we can clear its deferred write flag. */ bp->b_flags &= ~B_DEFERRED; } /* * bawrite: * * Asynchronous write. Start output on a buffer, but do not wait for * it to complete. The buffer is released when the output completes. * * bwrite() ( or the VOP routine anyway ) is responsible for handling * B_INVAL buffers. Not us. */ void bawrite(struct buf *bp) { bp->b_flags |= B_ASYNC; bwrite(bp); } /* * bowrite: * * Ordered write. Start output on a buffer, and flag it so that the * device will write it in the order it was queued. The buffer is * released when the output completes. bwrite() ( or the VOP routine * anyway ) is responsible for handling B_INVAL buffers. */ int bowrite(struct buf *bp) { bp->b_flags |= B_ORDERED | B_ASYNC; return (bwrite(bp)); } /* * bwillwrite: * * Called prior to the locking of any vnodes when we are expecting to * write. We do not want to starve the buffer cache with too many * dirty buffers so we block here. By blocking prior to the locking * of any vnodes we attempt to avoid the situation where a locked vnode * prevents the various system daemons from flushing related buffers. */ void bwillwrite(void) { if (numdirtybuffers >= hidirtybuffers) { crit_enter(); while (numdirtybuffers >= hidirtybuffers) { bd_wakeup(1); needsbuffer |= VFS_BIO_NEED_DIRTYFLUSH; tsleep(&needsbuffer, 0, "flswai", 0); } crit_exit(); } } /* * buf_dirty_count_severe: * * Return true if we have too many dirty buffers. */ int buf_dirty_count_severe(void) { return(numdirtybuffers >= hidirtybuffers); } /* * brelse: * * Release a busy buffer and, if requested, free its resources. The * buffer will be stashed in the appropriate bufqueue[] allowing it * to be accessed later as a cache entity or reused for other purposes. */ void brelse(struct buf *bp) { #ifdef INVARIANTS int saved_flags = bp->b_flags; #endif KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("brelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); crit_enter(); if ((bp->b_flags & (B_NOCACHE|B_DIRTY)) == (B_NOCACHE|B_DIRTY)) { printf("warning: buf %p marked dirty & B_NOCACHE, clearing B_NOCACHE\n", bp); bp->b_flags &= ~B_NOCACHE; } if (bp->b_flags & B_LOCKED) bp->b_flags &= ~B_ERROR; if (bp->b_cmd == BUF_CMD_WRITE && (bp->b_flags & (B_ERROR | B_INVAL)) == B_ERROR) { /* * Failed write, redirty. Must clear B_ERROR to prevent * pages from being scrapped. If B_INVAL is set then * this case is not run and the next case is run to * destroy the buffer. B_INVAL can occur if the buffer * is outside the range supported by the underlying device. */ bp->b_flags &= ~B_ERROR; bdirty(bp); } else if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR)) || (bp->b_bufsize <= 0) || bp->b_cmd == BUF_CMD_FREEBLKS) { /* * Either a failed I/O or we were asked to free or not * cache the buffer. */ bp->b_flags |= B_INVAL; if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) (*bioops.io_deallocate)(bp); if (bp->b_flags & B_DELWRI) { --numdirtybuffers; numdirtywakeup(lodirtybuffers); } bp->b_flags &= ~(B_DELWRI | B_CACHE); } /* * We must clear B_RELBUF if B_DELWRI is set. If vfs_vmio_release() * is called with B_DELWRI set, the underlying pages may wind up * getting freed causing a previous write (bdwrite()) to get 'lost' * because pages associated with a B_DELWRI bp are marked clean. * * We still allow the B_INVAL case to call vfs_vmio_release(), even * if B_DELWRI is set. * * If B_DELWRI is not set we may have to set B_RELBUF if we are low * on pages to return pages to the VM page queues. */ if (bp->b_flags & B_DELWRI) bp->b_flags &= ~B_RELBUF; else if (vm_page_count_severe()) bp->b_flags |= B_RELBUF; /* * At this point destroying the buffer is governed by the B_INVAL * or B_RELBUF flags. */ bp->b_cmd = BUF_CMD_DONE; /* * VMIO buffer rundown. It is not very necessary to keep a VMIO buffer * constituted, not even NFS buffers now. Two flags effect this. If * B_INVAL, the struct buf is invalidated but the VM object is kept * around ( i.e. so it is trivial to reconstitute the buffer later ). * * If B_ERROR or B_NOCACHE is set, pages in the VM object will be * invalidated. B_ERROR cannot be set for a failed write unless the * buffer is also B_INVAL because it hits the re-dirtying code above. * * Normally we can do this whether a buffer is B_DELWRI or not. If * the buffer is an NFS buffer, it is tracking piecemeal writes or * the commit state and we cannot afford to lose the buffer. */ if ((bp->b_flags & B_VMIO) && !(bp->b_vp->v_tag == VT_NFS && !vn_isdisk(bp->b_vp, NULL) && (bp->b_flags & B_DELWRI)) ) { /* * Rundown for VMIO buffers which are not dirty NFS buffers. */ int i, j, resid; vm_page_t m; off_t foff; vm_pindex_t poff; vm_object_t obj; struct vnode *vp; vp = bp->b_vp; /* * Get the base offset and length of the buffer. Note that * in the VMIO case if the buffer block size is not * page-aligned then b_data pointer may not be page-aligned. * But our b_xio.xio_pages array *IS* page aligned. * * block sizes less then DEV_BSIZE (usually 512) are not * supported due to the page granularity bits (m->valid, * m->dirty, etc...). * * See man buf(9) for more information */ resid = bp->b_bufsize; foff = bp->b_loffset; for (i = 0; i < bp->b_xio.xio_npages; i++) { m = bp->b_xio.xio_pages[i]; vm_page_flag_clear(m, PG_ZERO); /* * If we hit a bogus page, fixup *all* of them * now. Note that we left these pages wired * when we removed them so they had better exist, * and they cannot be ripped out from under us so * no critical section protection is necessary. */ if (m == bogus_page) { obj = vp->v_object; poff = OFF_TO_IDX(bp->b_loffset); for (j = i; j < bp->b_xio.xio_npages; j++) { vm_page_t mtmp; mtmp = bp->b_xio.xio_pages[j]; if (mtmp == bogus_page) { mtmp = vm_page_lookup(obj, poff + j); if (!mtmp) { panic("brelse: page missing"); } bp->b_xio.xio_pages[j] = mtmp; } } if ((bp->b_flags & B_INVAL) == 0) { pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_xio.xio_pages, bp->b_xio.xio_npages); } m = bp->b_xio.xio_pages[i]; } /* * Invalidate the backing store if B_NOCACHE is set * (e.g. used with vinvalbuf()). If this is NFS * we impose a requirement that the block size be * a multiple of PAGE_SIZE and create a temporary * hack to basically invalidate the whole page. The * problem is that NFS uses really odd buffer sizes * especially when tracking piecemeal writes and * it also vinvalbuf()'s a lot, which would result * in only partial page validation and invalidation * here. If the file page is mmap()'d, however, * all the valid bits get set so after we invalidate * here we would end up with weird m->valid values * like 0xfc. nfs_getpages() can't handle this so * we clear all the valid bits for the NFS case * instead of just some of them. * * The real bug is the VM system having to set m->valid * to VM_PAGE_BITS_ALL for faulted-in pages, which * itself is an artifact of the whole 512-byte * granular mess that exists to support odd block * sizes and UFS meta-data block sizes (e.g. 6144). * A complete rewrite is required. */ if (bp->b_flags & (B_NOCACHE|B_ERROR)) { int poffset = foff & PAGE_MASK; int presid; presid = PAGE_SIZE - poffset; if (bp->b_vp->v_tag == VT_NFS && bp->b_vp->v_type == VREG) { ; /* entire page */ } else if (presid > resid) { presid = resid; } KASSERT(presid >= 0, ("brelse: extra page")); vm_page_set_invalid(m, poffset, presid); } resid -= PAGE_SIZE - (foff & PAGE_MASK); foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; } if (bp->b_flags & (B_INVAL | B_RELBUF)) vfs_vmio_release(bp); } else if (bp->b_flags & B_VMIO) { /* * Rundown for VMIO buffers which are dirty NFS buffers. Such * buffers contain tracking ranges for NFS and cannot normally * be released. Due to the dirty check above this series of * conditionals, B_RELBUF probably will never be set in this * codepath. */ if (bp->b_flags & (B_INVAL | B_RELBUF)) vfs_vmio_release(bp); } else { /* * Rundown for non-VMIO buffers. */ if (bp->b_flags & (B_INVAL | B_RELBUF)) { #if 0 if (bp->b_vp) printf("brelse bp %p %08x/%08x: Warning, caught and fixed brelvp bug\n", bp, saved_flags, bp->b_flags); #endif if (bp->b_bufsize) allocbuf(bp, 0); if (bp->b_vp) brelvp(bp); } } if (bp->b_qindex != BQUEUE_NONE) panic("brelse: free buffer onto another queue???"); if (BUF_REFCNTNB(bp) > 1) { /* Temporary panic to verify exclusive locking */ /* This panic goes away when we allow shared refs */ panic("brelse: multiple refs"); /* do not release to free list */ BUF_UNLOCK(bp); crit_exit(); return; } /* * Figure out the correct queue to place the cleaned up buffer on. * Buffers placed in the EMPTY or EMPTYKVA had better already be * disassociated from their vnode. */ if (bp->b_bufsize == 0) { /* * Buffers with no memory. Due to conditionals near the top * of brelse() such buffers should probably already be * marked B_INVAL and disassociated from their vnode. */ bp->b_flags |= B_INVAL; KASSERT(bp->b_vp == NULL, ("bp1 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp)); KKASSERT((bp->b_flags & B_HASHED) == 0); if (bp->b_kvasize) { bp->b_qindex = BQUEUE_EMPTYKVA; } else { bp->b_qindex = BQUEUE_EMPTY; } TAILQ_INSERT_HEAD(&bufqueues[bp->b_qindex], bp, b_freelist); } else if (bp->b_flags & (B_ERROR | B_INVAL | B_NOCACHE | B_RELBUF)) { /* * Buffers with junk contents. Again these buffers had better * already be disassociated from their vnode. */ KASSERT(bp->b_vp == NULL, ("bp2 %p flags %08x/%08x vnode %p unexpectededly still associated!", bp, saved_flags, bp->b_flags, bp->b_vp)); KKASSERT((bp->b_flags & B_HASHED) == 0); bp->b_flags |= B_INVAL; bp->b_qindex = BQUEUE_CLEAN; TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); } else if (bp->b_flags & B_LOCKED) { /* * Buffers that are locked. */ bp->b_qindex = BQUEUE_LOCKED; TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist); } else { /* * Remaining buffers. These buffers are still associated with * their vnode. */ switch(bp->b_flags & (B_DELWRI|B_AGE)) { case B_DELWRI | B_AGE: bp->b_qindex = BQUEUE_DIRTY; TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); break; case B_DELWRI: bp->b_qindex = BQUEUE_DIRTY; TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); break; case B_AGE: bp->b_qindex = BQUEUE_CLEAN; TAILQ_INSERT_HEAD(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); break; default: bp->b_qindex = BQUEUE_CLEAN; TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); break; } } /* * If B_INVAL, clear B_DELWRI. We've already placed the buffer * on the correct queue. */ if ((bp->b_flags & (B_INVAL|B_DELWRI)) == (B_INVAL|B_DELWRI)) bundirty(bp); /* * Fixup numfreebuffers count. The bp is on an appropriate queue * unless locked. We then bump numfreebuffers if it is not B_DELWRI. * We've already handled the B_INVAL case ( B_DELWRI will be clear * if B_INVAL is set ). */ if ((bp->b_flags & B_LOCKED) == 0 && !(bp->b_flags & B_DELWRI)) bufcountwakeup(); /* * Something we can maybe free or reuse */ if (bp->b_bufsize || bp->b_kvasize) bufspacewakeup(); /* * Clean up temporary flags and unlock the buffer. */ bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF | B_DIRECT | B_NOWDRAIN); BUF_UNLOCK(bp); crit_exit(); } /* * bqrelse: * * Release a buffer back to the appropriate queue but do not try to free * it. The buffer is expected to be used again soon. * * bqrelse() is used by bdwrite() to requeue a delayed write, and used by * biodone() to requeue an async I/O on completion. It is also used when * known good buffers need to be requeued but we think we may need the data * again soon. * * XXX we should be able to leave the B_RELBUF hint set on completion. */ void bqrelse(struct buf *bp) { crit_enter(); KASSERT(!(bp->b_flags & (B_CLUSTER|B_PAGING)), ("bqrelse: inappropriate B_PAGING or B_CLUSTER bp %p", bp)); if (bp->b_qindex != BQUEUE_NONE) panic("bqrelse: free buffer onto another queue???"); if (BUF_REFCNTNB(bp) > 1) { /* do not release to free list */ panic("bqrelse: multiple refs"); BUF_UNLOCK(bp); crit_exit(); return; } if (bp->b_flags & B_LOCKED) { bp->b_flags &= ~B_ERROR; bp->b_qindex = BQUEUE_LOCKED; TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_LOCKED], bp, b_freelist); /* buffers with stale but valid contents */ } else if (bp->b_flags & B_DELWRI) { bp->b_qindex = BQUEUE_DIRTY; TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); } else if (vm_page_count_severe()) { /* * We are too low on memory, we have to try to free the * buffer (most importantly: the wired pages making up its * backing store) *now*. */ crit_exit(); brelse(bp); return; } else { bp->b_qindex = BQUEUE_CLEAN; TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_CLEAN], bp, b_freelist); } if ((bp->b_flags & B_LOCKED) == 0 && ((bp->b_flags & B_INVAL) || !(bp->b_flags & B_DELWRI))) { bufcountwakeup(); } /* * Something we can maybe free or reuse. */ if (bp->b_bufsize && !(bp->b_flags & B_DELWRI)) bufspacewakeup(); /* * Final cleanup and unlock. Clear bits that are only used while a * buffer is actively locked. */ bp->b_flags &= ~(B_ORDERED | B_ASYNC | B_NOCACHE | B_AGE | B_RELBUF); BUF_UNLOCK(bp); crit_exit(); } /* * vfs_vmio_release: * * Return backing pages held by the buffer 'bp' back to the VM system * if possible. The pages are freed if they are no longer valid or * attempt to free if it was used for direct I/O otherwise they are * sent to the page cache. * * Pages that were marked busy are left alone and skipped. * * The KVA mapping (b_data) for the underlying pages is removed by * this function. */ static void vfs_vmio_release(struct buf *bp) { int i; vm_page_t m; crit_enter(); for (i = 0; i < bp->b_xio.xio_npages; i++) { m = bp->b_xio.xio_pages[i]; bp->b_xio.xio_pages[i] = NULL; /* * In order to keep page LRU ordering consistent, put * everything on the inactive queue. */ vm_page_unwire(m, 0); /* * We don't mess with busy pages, it is * the responsibility of the process that * busied the pages to deal with them. */ if ((m->flags & PG_BUSY) || (m->busy != 0)) continue; if (m->wire_count == 0) { vm_page_flag_clear(m, PG_ZERO); /* * Might as well free the page if we can and it has * no valid data. We also free the page if the * buffer was used for direct I/O. */ if ((bp->b_flags & B_ASYNC) == 0 && !m->valid && m->hold_count == 0) { vm_page_busy(m); vm_page_protect(m, VM_PROT_NONE); vm_page_free(m); } else if (bp->b_flags & B_DIRECT) { vm_page_try_to_free(m); } else if (vm_page_count_severe()) { vm_page_try_to_cache(m); } } } crit_exit(); pmap_qremove(trunc_page((vm_offset_t) bp->b_data), bp->b_xio.xio_npages); if (bp->b_bufsize) { bufspacewakeup(); bp->b_bufsize = 0; } bp->b_xio.xio_npages = 0; bp->b_flags &= ~B_VMIO; if (bp->b_vp) brelvp(bp); } /* * vfs_bio_awrite: * * Implement clustered async writes for clearing out B_DELWRI buffers. * This is much better then the old way of writing only one buffer at * a time. Note that we may not be presented with the buffers in the * correct order, so we search for the cluster in both directions. * * The buffer is locked on call. */ int vfs_bio_awrite(struct buf *bp) { int i; int j; off_t loffset = bp->b_loffset; struct vnode *vp = bp->b_vp; int nbytes; struct buf *bpa; int nwritten; int size; crit_enter(); /* * right now we support clustered writing only to regular files. If * we find a clusterable block we could be in the middle of a cluster * rather then at the beginning. * * NOTE: b_bio1 contains the logical loffset and is aliased * to b_loffset. b_bio2 contains the translated block number. */ if ((vp->v_type == VREG) && (vp->v_mount != 0) && /* Only on nodes that have the size info */ (bp->b_flags & (B_CLUSTEROK | B_INVAL)) == B_CLUSTEROK) { size = vp->v_mount->mnt_stat.f_iosize; for (i = size; i < MAXPHYS; i += size) { if ((bpa = findblk(vp, loffset + i)) && BUF_REFCNT(bpa) == 0 && ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == (B_DELWRI | B_CLUSTEROK)) && (bpa->b_bufsize == size)) { if ((bpa->b_bio2.bio_offset == NOOFFSET) || (bpa->b_bio2.bio_offset != bp->b_bio2.bio_offset + i)) break; } else { break; } } for (j = size; i + j <= MAXPHYS && j <= loffset; j += size) { if ((bpa = findblk(vp, loffset - j)) && BUF_REFCNT(bpa) == 0 && ((bpa->b_flags & (B_DELWRI | B_CLUSTEROK | B_INVAL)) == (B_DELWRI | B_CLUSTEROK)) && (bpa->b_bufsize == size)) { if ((bpa->b_bio2.bio_offset == NOOFFSET) || (bpa->b_bio2.bio_offset != bp->b_bio2.bio_offset - j)) break; } else { break; } } j -= size; nbytes = (i + j); /* * this is a possible cluster write */ if (nbytes != size) { BUF_UNLOCK(bp); nwritten = cluster_wbuild(vp, size, loffset - j, nbytes); crit_exit(); return nwritten; } } bremfree(bp); bp->b_flags |= B_ASYNC; crit_exit(); /* * default (old) behavior, writing out only one block * * XXX returns b_bufsize instead of b_bcount for nwritten? */ nwritten = bp->b_bufsize; bwrite(bp); return nwritten; } /* * getnewbuf: * * Find and initialize a new buffer header, freeing up existing buffers * in the bufqueues as necessary. The new buffer is returned locked. * * Important: B_INVAL is not set. If the caller wishes to throw the * buffer away, the caller must set B_INVAL prior to calling brelse(). * * We block if: * We have insufficient buffer headers * We have insufficient buffer space * buffer_map is too fragmented ( space reservation fails ) * If we have to flush dirty buffers ( but we try to avoid this ) * * To avoid VFS layer recursion we do not flush dirty buffers ourselves. * Instead we ask the buf daemon to do it for us. We attempt to * avoid piecemeal wakeups of the pageout daemon. */ static struct buf * getnewbuf(int slpflag, int slptimeo, int size, int maxsize) { struct buf *bp; struct buf *nbp; int defrag = 0; int nqindex; static int flushingbufs; /* * We can't afford to block since we might be holding a vnode lock, * which may prevent system daemons from running. We deal with * low-memory situations by proactively returning memory and running * async I/O rather then sync I/O. */ ++getnewbufcalls; --getnewbufrestarts; restart: ++getnewbufrestarts; /* * Setup for scan. If we do not have enough free buffers, * we setup a degenerate case that immediately fails. Note * that if we are specially marked process, we are allowed to * dip into our reserves. * * The scanning sequence is nominally: EMPTY->EMPTYKVA->CLEAN * * We start with EMPTYKVA. If the list is empty we backup to EMPTY. * However, there are a number of cases (defragging, reusing, ...) * where we cannot backup. */ nqindex = BQUEUE_EMPTYKVA; nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]); if (nbp == NULL) { /* * If no EMPTYKVA buffers and we are either * defragging or reusing, locate a CLEAN buffer * to free or reuse. If bufspace useage is low * skip this step so we can allocate a new buffer. */ if (defrag || bufspace >= lobufspace) { nqindex = BQUEUE_CLEAN; nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]); } /* * If we could not find or were not allowed to reuse a * CLEAN buffer, check to see if it is ok to use an EMPTY * buffer. We can only use an EMPTY buffer if allocating * its KVA would not otherwise run us out of buffer space. */ if (nbp == NULL && defrag == 0 && bufspace + maxsize < hibufspace) { nqindex = BQUEUE_EMPTY; nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTY]); } } /* * Run scan, possibly freeing data and/or kva mappings on the fly * depending. */ while ((bp = nbp) != NULL) { int qindex = nqindex; /* * Calculate next bp ( we can only use it if we do not block * or do other fancy things ). */ if ((nbp = TAILQ_NEXT(bp, b_freelist)) == NULL) { switch(qindex) { case BQUEUE_EMPTY: nqindex = BQUEUE_EMPTYKVA; if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_EMPTYKVA]))) break; /* fall through */ case BQUEUE_EMPTYKVA: nqindex = BQUEUE_CLEAN; if ((nbp = TAILQ_FIRST(&bufqueues[BQUEUE_CLEAN]))) break; /* fall through */ case BQUEUE_CLEAN: /* * nbp is NULL. */ break; } } /* * Sanity Checks */ KASSERT(bp->b_qindex == qindex, ("getnewbuf: inconsistant queue %d bp %p", qindex, bp)); /* * Note: we no longer distinguish between VMIO and non-VMIO * buffers. */ KASSERT((bp->b_flags & B_DELWRI) == 0, ("delwri buffer %p found in queue %d", bp, qindex)); /* * If we are defragging then we need a buffer with * b_kvasize != 0. XXX this situation should no longer * occur, if defrag is non-zero the buffer's b_kvasize * should also be non-zero at this point. XXX */ if (defrag && bp->b_kvasize == 0) { printf("Warning: defrag empty buffer %p\n", bp); continue; } /* * Start freeing the bp. This is somewhat involved. nbp * remains valid only for BQUEUE_EMPTY[KVA] bp's. Buffers * on the clean list must be disassociated from their * current vnode. Buffers on the empty[kva] lists have * already been disassociated. */ if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) { printf("getnewbuf: warning, locked buf %p, race corrected\n", bp); tsleep(&bd_request, 0, "gnbxxx", hz / 100); goto restart; } if (bp->b_qindex != qindex) { printf("getnewbuf: warning, BUF_LOCK blocked unexpectedly on buf %p index %d->%d, race corrected\n", bp, qindex, bp->b_qindex); BUF_UNLOCK(bp); goto restart; } bremfree(bp); if (qindex == BQUEUE_CLEAN) { if (bp->b_flags & B_VMIO) { bp->b_flags &= ~B_ASYNC; vfs_vmio_release(bp); } if (bp->b_vp) brelvp(bp); } /* * NOTE: nbp is now entirely invalid. We can only restart * the scan from this point on. * * Get the rest of the buffer freed up. b_kva* is still * valid after this operation. */ KASSERT(bp->b_vp == NULL, ("bp3 %p flags %08x vnode %p qindex %d unexpectededly still associated!", bp, bp->b_flags, bp->b_vp, qindex)); KKASSERT((bp->b_flags & B_HASHED) == 0); if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_deallocate) (*bioops.io_deallocate)(bp); /* * critical section protection is not required when * scrapping a buffer's contents because it is already * wired. */ if (bp->b_bufsize) allocbuf(bp, 0); bp->b_flags = B_BNOCLIP; bp->b_cmd = BUF_CMD_DONE; bp->b_vp = NULL; bp->b_error = 0; bp->b_resid = 0; bp->b_bcount = 0; bp->b_xio.xio_npages = 0; bp->b_dirtyoff = bp->b_dirtyend = 0; reinitbufbio(bp); LIST_INIT(&bp->b_dep); /* * If we are defragging then free the buffer. */ if (defrag) { bp->b_flags |= B_INVAL; bfreekva(bp); brelse(bp); defrag = 0; goto restart; } /* * If we are overcomitted then recover the buffer and its * KVM space. This occurs in rare situations when multiple * processes are blocked in getnewbuf() or allocbuf(). */ if (bufspace >= hibufspace) flushingbufs = 1; if (flushingbufs && bp->b_kvasize != 0) { bp->b_flags |= B_INVAL; bfreekva(bp); brelse(bp); goto restart; } if (bufspace < lobufspace) flushingbufs = 0; break; } /* * If we exhausted our list, sleep as appropriate. We may have to * wakeup various daemons and write out some dirty buffers. * * Generally we are sleeping due to insufficient buffer space. */ if (bp == NULL) { int flags; char *waitmsg; if (defrag) { flags = VFS_BIO_NEED_BUFSPACE; waitmsg = "nbufkv"; } else if (bufspace >= hibufspace) { waitmsg = "nbufbs"; flags = VFS_BIO_NEED_BUFSPACE; } else { waitmsg = "newbuf"; flags = VFS_BIO_NEED_ANY; } bd_speedup(); /* heeeelp */ needsbuffer |= flags; while (needsbuffer & flags) { if (tsleep(&needsbuffer, slpflag, waitmsg, slptimeo)) return (NULL); } } else { /* * We finally have a valid bp. We aren't quite out of the * woods, we still have to reserve kva space. In order * to keep fragmentation sane we only allocate kva in * BKVASIZE chunks. */ maxsize = (maxsize + BKVAMASK) & ~BKVAMASK; if (maxsize != bp->b_kvasize) { vm_offset_t addr = 0; int count; bfreekva(bp); count = vm_map_entry_reserve(MAP_RESERVE_COUNT); vm_map_lock(buffer_map); if (vm_map_findspace(buffer_map, vm_map_min(buffer_map), maxsize, maxsize, &addr)) { /* * Uh oh. Buffer map is too fragmented. We * must defragment the map. */ vm_map_unlock(buffer_map); vm_map_entry_release(count); ++bufdefragcnt; defrag = 1; bp->b_flags |= B_INVAL; brelse(bp); goto restart; } if (addr) { vm_map_insert(buffer_map, &count, NULL, 0, addr, addr + maxsize, VM_PROT_ALL, VM_PROT_ALL, MAP_NOFAULT); bp->b_kvabase = (caddr_t) addr; bp->b_kvasize = maxsize; bufspace += bp->b_kvasize; ++bufreusecnt; } vm_map_unlock(buffer_map); vm_map_entry_release(count); } bp->b_data = bp->b_kvabase; } return(bp); } /* * buf_daemon: * * Buffer flushing daemon. Buffers are normally flushed by the * update daemon but if it cannot keep up this process starts to * take the load in an attempt to prevent getnewbuf() from blocking. */ static struct thread *bufdaemonthread; static struct kproc_desc buf_kp = { "bufdaemon", buf_daemon, &bufdaemonthread }; SYSINIT(bufdaemon, SI_SUB_KTHREAD_BUF, SI_ORDER_FIRST, kproc_start, &buf_kp) static void buf_daemon() { /* * This process needs to be suspended prior to shutdown sync. */ EVENTHANDLER_REGISTER(shutdown_pre_sync, shutdown_kproc, bufdaemonthread, SHUTDOWN_PRI_LAST); /* * This process is allowed to take the buffer cache to the limit */ crit_enter(); for (;;) { kproc_suspend_loop(); /* * Do the flush. Limit the amount of in-transit I/O we * allow to build up, otherwise we would completely saturate * the I/O system. Wakeup any waiting processes before we * normally would so they can run in parallel with our drain. */ while (numdirtybuffers > lodirtybuffers) { if (flushbufqueues() == 0) break; waitrunningbufspace(); numdirtywakeup((lodirtybuffers + hidirtybuffers) / 2); } /* * Only clear bd_request if we have reached our low water * mark. The buf_daemon normally waits 5 seconds and * then incrementally flushes any dirty buffers that have * built up, within reason. * * If we were unable to hit our low water mark and couldn't * find any flushable buffers, we sleep half a second. * Otherwise we loop immediately. */ if (numdirtybuffers <= lodirtybuffers) { /* * We reached our low water mark, reset the * request and sleep until we are needed again. * The sleep is just so the suspend code works. */ bd_request = 0; tsleep(&bd_request, 0, "psleep", hz); } else { /* * We couldn't find any flushable dirty buffers but * still have too many dirty buffers, we * have to sleep and try again. (rare) */ tsleep(&bd_request, 0, "qsleep", hz / 2); } } } /* * flushbufqueues: * * Try to flush a buffer in the dirty queue. We must be careful to * free up B_INVAL buffers instead of write them, which NFS is * particularly sensitive to. */ static int flushbufqueues(void) { struct buf *bp; int r = 0; bp = TAILQ_FIRST(&bufqueues[BQUEUE_DIRTY]); while (bp) { KASSERT((bp->b_flags & B_DELWRI), ("unexpected clean buffer %p", bp)); if (bp->b_flags & B_DELWRI) { if (bp->b_flags & B_INVAL) { if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) != 0) panic("flushbufqueues: locked buf"); bremfree(bp); brelse(bp); ++r; break; } if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_countdeps && (bp->b_flags & B_DEFERRED) == 0 && (*bioops.io_countdeps)(bp, 0)) { TAILQ_REMOVE(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); TAILQ_INSERT_TAIL(&bufqueues[BQUEUE_DIRTY], bp, b_freelist); bp->b_flags |= B_DEFERRED; bp = TAILQ_FIRST(&bufqueues[BQUEUE_DIRTY]); continue; } /* * Only write it out if we can successfully lock * it. */ if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT) == 0) { vfs_bio_awrite(bp); ++r; break; } } bp = TAILQ_NEXT(bp, b_freelist); } return (r); } /* * inmem: * * Returns true if no I/O is needed to access the associated VM object. * This is like findblk except it also hunts around in the VM system for * the data. * * Note that we ignore vm_page_free() races from interrupts against our * lookup, since if the caller is not protected our return value will not * be any more valid then otherwise once we exit the critical section. */ int inmem(struct vnode *vp, off_t loffset) { vm_object_t obj; vm_offset_t toff, tinc, size; vm_page_t m; if (findblk(vp, loffset)) return 1; if (vp->v_mount == NULL) return 0; if ((obj = vp->v_object) == NULL) return 0; size = PAGE_SIZE; if (size > vp->v_mount->mnt_stat.f_iosize) size = vp->v_mount->mnt_stat.f_iosize; for (toff = 0; toff < vp->v_mount->mnt_stat.f_iosize; toff += tinc) { m = vm_page_lookup(obj, OFF_TO_IDX(loffset + toff)); if (m == NULL) return 0; tinc = size; if (tinc > PAGE_SIZE - ((toff + loffset) & PAGE_MASK)) tinc = PAGE_SIZE - ((toff + loffset) & PAGE_MASK); if (vm_page_is_valid(m, (vm_offset_t) ((toff + loffset) & PAGE_MASK), tinc) == 0) return 0; } return 1; } /* * vfs_setdirty: * * Sets the dirty range for a buffer based on the status of the dirty * bits in the pages comprising the buffer. * * The range is limited to the size of the buffer. * * This routine is primarily used by NFS, but is generalized for the * B_VMIO case. */ static void vfs_setdirty(struct buf *bp) { int i; vm_object_t object; /* * Degenerate case - empty buffer */ if (bp->b_bufsize == 0) return; /* * We qualify the scan for modified pages on whether the * object has been flushed yet. The OBJ_WRITEABLE flag * is not cleared simply by protecting pages off. */ if ((bp->b_flags & B_VMIO) == 0) return; object = bp->b_xio.xio_pages[0]->object; if ((object->flags & OBJ_WRITEABLE) && !(object->flags & OBJ_MIGHTBEDIRTY)) printf("Warning: object %p writeable but not mightbedirty\n", object); if (!(object->flags & OBJ_WRITEABLE) && (object->flags & OBJ_MIGHTBEDIRTY)) printf("Warning: object %p mightbedirty but not writeable\n", object); if (object->flags & (OBJ_MIGHTBEDIRTY|OBJ_CLEANING)) { vm_offset_t boffset; vm_offset_t eoffset; /* * test the pages to see if they have been modified directly * by users through the VM system. */ for (i = 0; i < bp->b_xio.xio_npages; i++) { vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO); vm_page_test_dirty(bp->b_xio.xio_pages[i]); } /* * Calculate the encompassing dirty range, boffset and eoffset, * (eoffset - boffset) bytes. */ for (i = 0; i < bp->b_xio.xio_npages; i++) { if (bp->b_xio.xio_pages[i]->dirty) break; } boffset = (i << PAGE_SHIFT) - (bp->b_loffset & PAGE_MASK); for (i = bp->b_xio.xio_npages - 1; i >= 0; --i) { if (bp->b_xio.xio_pages[i]->dirty) { break; } } eoffset = ((i + 1) << PAGE_SHIFT) - (bp->b_loffset & PAGE_MASK); /* * Fit it to the buffer. */ if (eoffset > bp->b_bcount) eoffset = bp->b_bcount; /* * If we have a good dirty range, merge with the existing * dirty range. */ if (boffset < eoffset) { if (bp->b_dirtyoff > boffset) bp->b_dirtyoff = boffset; if (bp->b_dirtyend < eoffset) bp->b_dirtyend = eoffset; } } } /* * findblk: * * Locate and return the specified buffer, or NULL if the buffer does * not exist. Do not attempt to lock the buffer or manipulate it in * any way. The caller must validate that the correct buffer has been * obtain after locking it. */ struct buf * findblk(struct vnode *vp, off_t loffset) { struct buf *bp; crit_enter(); bp = buf_rb_hash_RB_LOOKUP(&vp->v_rbhash_tree, loffset); crit_exit(); return(bp); } /* * getblk: * * Get a block given a specified block and offset into a file/device. * B_INVAL may or may not be set on return. The caller should clear * B_INVAL prior to initiating a READ. * * IT IS IMPORTANT TO UNDERSTAND THAT IF YOU CALL GETBLK() AND B_CACHE * IS NOT SET, YOU MUST INITIALIZE THE RETURNED BUFFER, ISSUE A READ, * OR SET B_INVAL BEFORE RETIRING IT. If you retire a getblk'd buffer * without doing any of those things the system will likely believe * the buffer to be valid (especially if it is not B_VMIO), and the * next getblk() will return the buffer with B_CACHE set. * * For a non-VMIO buffer, B_CACHE is set to the opposite of B_INVAL for * an existing buffer. * * For a VMIO buffer, B_CACHE is modified according to the backing VM. * If getblk()ing a previously 0-sized invalid buffer, B_CACHE is set * and then cleared based on the backing VM. If the previous buffer is * non-0-sized but invalid, B_CACHE will be cleared. * * If getblk() must create a new buffer, the new buffer is returned with * both B_INVAL and B_CACHE clear unless it is a VMIO buffer, in which * case it is returned with B_INVAL clear and B_CACHE set based on the * backing VM. * * getblk() also forces a bwrite() for any B_DELWRI buffer whos * B_CACHE bit is clear. * * What this means, basically, is that the caller should use B_CACHE to * determine whether the buffer is fully valid or not and should clear * B_INVAL prior to issuing a read. If the caller intends to validate * the buffer by loading its data area with something, the caller needs * to clear B_INVAL. If the caller does this without issuing an I/O, * the caller should set B_CACHE ( as an optimization ), else the caller * should issue the I/O and biodone() will set B_CACHE if the I/O was * a write attempt or if it was a successfull read. If the caller * intends to issue a READ, the caller must clear B_INVAL and B_ERROR * prior to issuing the READ. biodone() will *not* clear B_INVAL. */ struct buf * getblk(struct vnode *vp, off_t loffset, int size, int slpflag, int slptimeo) { struct buf *bp; if (size > MAXBSIZE) panic("getblk: size(%d) > MAXBSIZE(%d)", size, MAXBSIZE); if (vp->v_object == NULL) panic("getblk: vnode %p has no object!", vp); crit_enter(); loop: /* * Block if we are low on buffers. Certain processes are allowed * to completely exhaust the buffer cache. * * If this check ever becomes a bottleneck it may be better to * move it into the else, when findblk() fails. At the moment * it isn't a problem. * * XXX remove, we cannot afford to block anywhere if holding a vnode * lock in low-memory situation, so take it to the max. */ if (numfreebuffers == 0) { if (!curproc) return NULL; needsbuffer |= VFS_BIO_NEED_ANY; tsleep(&needsbuffer, slpflag, "newbuf", slptimeo); } if ((bp = findblk(vp, loffset))) { /* * The buffer was found in the cache, but we need to lock it. * Even with LK_NOWAIT the lockmgr may break our critical * section, so double-check the validity of the buffer * once the lock has been obtained. */ if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT)) { int lkflags = LK_EXCLUSIVE | LK_SLEEPFAIL; if (slpflag & PCATCH) lkflags |= LK_PCATCH; if (BUF_TIMELOCK(bp, lkflags, "getblk", slptimeo) == ENOLCK) { goto loop; } crit_exit(); return (NULL); } /* * Once the buffer has been locked, make sure we didn't race * a buffer recyclement. Buffers that are no longer hashed * will have b_vp == NULL, so this takes care of that check * as well. */ if (bp->b_vp != vp || bp->b_loffset != loffset) { printf("Warning buffer %p (vp %p loffset %lld) was recycled\n", bp, vp, loffset); BUF_UNLOCK(bp); goto loop; } /* * All vnode-based buffers must be backed by a VM object. */ KKASSERT(bp->b_flags & B_VMIO); KKASSERT(bp->b_cmd == BUF_CMD_DONE); /* * Make sure that B_INVAL buffers do not have a cached * block number translation. */ if ((bp->b_flags & B_INVAL) && (bp->b_bio2.bio_offset != NOOFFSET)) { printf("Warning invalid buffer %p (vp %p loffset %lld) did not have cleared bio_offset cache\n", bp, vp, loffset); clearbiocache(&bp->b_bio2); } /* * The buffer is locked. B_CACHE is cleared if the buffer is * invalid. */ if (bp->b_flags & B_INVAL) bp->b_flags &= ~B_CACHE; bremfree(bp); /* * Any size inconsistancy with a dirty buffer or a buffer * with a softupdates dependancy must be resolved. Resizing * the buffer in such circumstances can lead to problems. */ if (size != bp->b_bcount) { if (bp->b_flags & B_DELWRI) { bp->b_flags |= B_NOCACHE; bwrite(bp); } else if (LIST_FIRST(&bp->b_dep)) { bp->b_flags |= B_NOCACHE; bwrite(bp); } else { bp->b_flags |= B_RELBUF; brelse(bp); } goto loop; } KKASSERT(size <= bp->b_kvasize); KASSERT(bp->b_loffset != NOOFFSET, ("getblk: no buffer offset")); /* * A buffer with B_DELWRI set and B_CACHE clear must * be committed before we can return the buffer in * order to prevent the caller from issuing a read * ( due to B_CACHE not being set ) and overwriting * it. * * Most callers, including NFS and FFS, need this to * operate properly either because they assume they * can issue a read if B_CACHE is not set, or because * ( for example ) an uncached B_DELWRI might loop due * to softupdates re-dirtying the buffer. In the latter * case, B_CACHE is set after the first write completes, * preventing further loops. * * NOTE! b*write() sets B_CACHE. If we cleared B_CACHE * above while extending the buffer, we cannot allow the * buffer to remain with B_CACHE set after the write * completes or it will represent a corrupt state. To * deal with this we set B_NOCACHE to scrap the buffer * after the write. * * We might be able to do something fancy, like setting * B_CACHE in bwrite() except if B_DELWRI is already set, * so the below call doesn't set B_CACHE, but that gets real * confusing. This is much easier. */ if ((bp->b_flags & (B_CACHE|B_DELWRI)) == B_DELWRI) { bp->b_flags |= B_NOCACHE; bwrite(bp); goto loop; } crit_exit(); } else { /* * Buffer is not in-core, create new buffer. The buffer * returned by getnewbuf() is locked. Note that the returned * buffer is also considered valid (not marked B_INVAL). * * Calculating the offset for the I/O requires figuring out * the block size. We use DEV_BSIZE for VBLK or VCHR and * the mount's f_iosize otherwise. If the vnode does not * have an associated mount we assume that the passed size is * the block size. * * Note that vn_isdisk() cannot be used here since it may * return a failure for numerous reasons. Note that the * buffer size may be larger then the block size (the caller * will use block numbers with the proper multiple). Beware * of using any v_* fields which are part of unions. In * particular, in DragonFly the mount point overloading * mechanism is such that the underlying directory (with a * non-NULL v_mountedhere) is not a special case. */ int bsize, maxsize; if (vp->v_type == VBLK || vp->v_type == VCHR) bsize = DEV_BSIZE; else if (vp->v_mount) bsize = vp->v_mount->mnt_stat.f_iosize; else bsize = size; maxsize = size + (loffset & PAGE_MASK); maxsize = imax(maxsize, bsize); if ((bp = getnewbuf(slpflag, slptimeo, size, maxsize)) == NULL) { if (slpflag || slptimeo) { crit_exit(); return NULL; } goto loop; } /* * This code is used to make sure that a buffer is not * created while the getnewbuf routine is blocked. * This can be a problem whether the vnode is locked or not. * If the buffer is created out from under us, we have to * throw away the one we just created. There is now window * race because we are safely running in a critical section * from the point of the duplicate buffer creation through * to here, and we've locked the buffer. */ if (findblk(vp, loffset)) { bp->b_flags |= B_INVAL; brelse(bp); goto loop; } /* * Insert the buffer into the hash, so that it can * be found by findblk(). * * Make sure the translation layer has been cleared. */ bp->b_loffset = loffset; bp->b_bio2.bio_offset = NOOFFSET; /* bp->b_bio2.bio_next = NULL; */ bgetvp(vp, bp); /* * All vnode-based buffers must be backed by a VM object. */ KKASSERT(vp->v_object != NULL); bp->b_flags |= B_VMIO; KKASSERT(bp->b_cmd == BUF_CMD_DONE); allocbuf(bp, size); crit_exit(); } return (bp); } /* * geteblk: * * Get an empty, disassociated buffer of given size. The buffer is * initially set to B_INVAL. * * critical section protection is not required for the allocbuf() * call because races are impossible here. */ struct buf * geteblk(int size) { struct buf *bp; int maxsize; maxsize = (size + BKVAMASK) & ~BKVAMASK; crit_enter(); while ((bp = getnewbuf(0, 0, size, maxsize)) == 0) ; crit_exit(); allocbuf(bp, size); bp->b_flags |= B_INVAL; /* b_dep cleared by getnewbuf() */ return (bp); } /* * allocbuf: * * This code constitutes the buffer memory from either anonymous system * memory (in the case of non-VMIO operations) or from an associated * VM object (in the case of VMIO operations). This code is able to * resize a buffer up or down. * * Note that this code is tricky, and has many complications to resolve * deadlock or inconsistant data situations. Tread lightly!!! * There are B_CACHE and B_DELWRI interactions that must be dealt with by * the caller. Calling this code willy nilly can result in the loss of data. * * allocbuf() only adjusts B_CACHE for VMIO buffers. getblk() deals with * B_CACHE for the non-VMIO case. * * This routine does not need to be called from a critical section but you * must own the buffer. */ int allocbuf(struct buf *bp, int size) { int newbsize, mbsize; int i; if (BUF_REFCNT(bp) == 0) panic("allocbuf: buffer not busy"); if (bp->b_kvasize < size) panic("allocbuf: buffer too small"); if ((bp->b_flags & B_VMIO) == 0) { caddr_t origbuf; int origbufsize; /* * Just get anonymous memory from the kernel. Don't * mess with B_CACHE. */ mbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); if (bp->b_flags & B_MALLOC) newbsize = mbsize; else newbsize = round_page(size); if (newbsize < bp->b_bufsize) { /* * Malloced buffers are not shrunk */ if (bp->b_flags & B_MALLOC) { if (newbsize) { bp->b_bcount = size; } else { free(bp->b_data, M_BIOBUF); if (bp->b_bufsize) { bufmallocspace -= bp->b_bufsize; bufspacewakeup(); bp->b_bufsize = 0; } bp->b_data = bp->b_kvabase; bp->b_bcount = 0; bp->b_flags &= ~B_MALLOC; } return 1; } vm_hold_free_pages( bp, (vm_offset_t) bp->b_data + newbsize, (vm_offset_t) bp->b_data + bp->b_bufsize); } else if (newbsize > bp->b_bufsize) { /* * We only use malloced memory on the first allocation. * and revert to page-allocated memory when the buffer * grows. */ if ((bufmallocspace < maxbufmallocspace) && (bp->b_bufsize == 0) && (mbsize <= PAGE_SIZE/2)) { bp->b_data = malloc(mbsize, M_BIOBUF, M_WAITOK); bp->b_bufsize = mbsize; bp->b_bcount = size; bp->b_flags |= B_MALLOC; bufmallocspace += mbsize; return 1; } origbuf = NULL; origbufsize = 0; /* * If the buffer is growing on its other-than-first * allocation, then we revert to the page-allocation * scheme. */ if (bp->b_flags & B_MALLOC) { origbuf = bp->b_data; origbufsize = bp->b_bufsize; bp->b_data = bp->b_kvabase; if (bp->b_bufsize) { bufmallocspace -= bp->b_bufsize; bufspacewakeup(); bp->b_bufsize = 0; } bp->b_flags &= ~B_MALLOC; newbsize = round_page(newbsize); } vm_hold_load_pages( bp, (vm_offset_t) bp->b_data + bp->b_bufsize, (vm_offset_t) bp->b_data + newbsize); if (origbuf) { bcopy(origbuf, bp->b_data, origbufsize); free(origbuf, M_BIOBUF); } } } else { vm_page_t m; int desiredpages; newbsize = (size + DEV_BSIZE - 1) & ~(DEV_BSIZE - 1); desiredpages = ((int)(bp->b_loffset & PAGE_MASK) + newbsize + PAGE_MASK) >> PAGE_SHIFT; KKASSERT(desiredpages <= XIO_INTERNAL_PAGES); if (bp->b_flags & B_MALLOC) panic("allocbuf: VMIO buffer can't be malloced"); /* * Set B_CACHE initially if buffer is 0 length or will become * 0-length. */ if (size == 0 || bp->b_bufsize == 0) bp->b_flags |= B_CACHE; if (newbsize < bp->b_bufsize) { /* * DEV_BSIZE aligned new buffer size is less then the * DEV_BSIZE aligned existing buffer size. Figure out * if we have to remove any pages. */ if (desiredpages < bp->b_xio.xio_npages) { for (i = desiredpages; i < bp->b_xio.xio_npages; i++) { /* * the page is not freed here -- it * is the responsibility of * vnode_pager_setsize */ m = bp->b_xio.xio_pages[i]; KASSERT(m != bogus_page, ("allocbuf: bogus page found")); while (vm_page_sleep_busy(m, TRUE, "biodep")) ; bp->b_xio.xio_pages[i] = NULL; vm_page_unwire(m, 0); } pmap_qremove((vm_offset_t) trunc_page((vm_offset_t)bp->b_data) + (desiredpages << PAGE_SHIFT), (bp->b_xio.xio_npages - desiredpages)); bp->b_xio.xio_npages = desiredpages; } } else if (size > bp->b_bcount) { /* * We are growing the buffer, possibly in a * byte-granular fashion. */ struct vnode *vp; vm_object_t obj; vm_offset_t toff; vm_offset_t tinc; /* * Step 1, bring in the VM pages from the object, * allocating them if necessary. We must clear * B_CACHE if these pages are not valid for the * range covered by the buffer. * * critical section protection is required to protect * against interrupts unbusying and freeing pages * between our vm_page_lookup() and our * busycheck/wiring call. */ vp = bp->b_vp; obj = vp->v_object; crit_enter(); while (bp->b_xio.xio_npages < desiredpages) { vm_page_t m; vm_pindex_t pi; pi = OFF_TO_IDX(bp->b_loffset) + bp->b_xio.xio_npages; if ((m = vm_page_lookup(obj, pi)) == NULL) { /* * note: must allocate system pages * since blocking here could intefere * with paging I/O, no matter which * process we are. */ m = vm_page_alloc(obj, pi, VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM); if (m == NULL) { vm_wait(); vm_pageout_deficit += desiredpages - bp->b_xio.xio_npages; } else { vm_page_wire(m); vm_page_wakeup(m); bp->b_flags &= ~B_CACHE; bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; ++bp->b_xio.xio_npages; } continue; } /* * We found a page. If we have to sleep on it, * retry because it might have gotten freed out * from under us. * * We can only test PG_BUSY here. Blocking on * m->busy might lead to a deadlock: * * vm_fault->getpages->cluster_read->allocbuf * */ if (vm_page_sleep_busy(m, FALSE, "pgtblk")) continue; /* * We have a good page. Should we wakeup the * page daemon? */ if ((curthread != pagethread) && ((m->queue - m->pc) == PQ_CACHE) && ((vmstats.v_free_count + vmstats.v_cache_count) < (vmstats.v_free_min + vmstats.v_cache_min))) { pagedaemon_wakeup(); } vm_page_flag_clear(m, PG_ZERO); vm_page_wire(m); bp->b_xio.xio_pages[bp->b_xio.xio_npages] = m; ++bp->b_xio.xio_npages; } crit_exit(); /* * Step 2. We've loaded the pages into the buffer, * we have to figure out if we can still have B_CACHE * set. Note that B_CACHE is set according to the * byte-granular range ( bcount and size ), not the * aligned range ( newbsize ). * * The VM test is against m->valid, which is DEV_BSIZE * aligned. Needless to say, the validity of the data * needs to also be DEV_BSIZE aligned. Note that this * fails with NFS if the server or some other client * extends the file's EOF. If our buffer is resized, * B_CACHE may remain set! XXX */ toff = bp->b_bcount; tinc = PAGE_SIZE - ((bp->b_loffset + toff) & PAGE_MASK); while ((bp->b_flags & B_CACHE) && toff < size) { vm_pindex_t pi; if (tinc > (size - toff)) tinc = size - toff; pi = ((bp->b_loffset & PAGE_MASK) + toff) >> PAGE_SHIFT; vfs_buf_test_cache( bp, bp->b_loffset, toff, tinc, bp->b_xio.xio_pages[pi] ); toff += tinc; tinc = PAGE_SIZE; } /* * Step 3, fixup the KVM pmap. Remember that * bp->b_data is relative to bp->b_loffset, but * bp->b_loffset may be offset into the first page. */ bp->b_data = (caddr_t) trunc_page((vm_offset_t)bp->b_data); pmap_qenter( (vm_offset_t)bp->b_data, bp->b_xio.xio_pages, bp->b_xio.xio_npages ); bp->b_data = (caddr_t)((vm_offset_t)bp->b_data | (vm_offset_t)(bp->b_loffset & PAGE_MASK)); } } if (newbsize < bp->b_bufsize) bufspacewakeup(); bp->b_bufsize = newbsize; /* actual buffer allocation */ bp->b_bcount = size; /* requested buffer size */ return 1; } /* * biowait: * * Wait for buffer I/O completion, returning error status. The buffer * is left locked on return. B_EINTR is converted into an EINTR error * and cleared. * * NOTE! The original b_cmd is lost on return, since b_cmd will be * set to BUF_CMD_DONE. */ int biowait(struct buf *bp) { crit_enter(); while (bp->b_cmd != BUF_CMD_DONE) { if (bp->b_cmd == BUF_CMD_READ) tsleep(bp, 0, "biord", 0); else tsleep(bp, 0, "biowr", 0); } crit_exit(); if (bp->b_flags & B_EINTR) { bp->b_flags &= ~B_EINTR; return (EINTR); } if (bp->b_flags & B_ERROR) { return (bp->b_error ? bp->b_error : EIO); } else { return (0); } } /* * This associates a tracking count with an I/O. vn_strategy() and * dev_dstrategy() do this automatically but there are a few cases * where a vnode or device layer is bypassed when a block translation * is cached. In such cases bio_start_transaction() may be called on * the bypassed layers so the system gets an I/O in progress indication * for those higher layers. */ void bio_start_transaction(struct bio *bio, struct bio_track *track) { bio->bio_track = track; atomic_add_int(&track->bk_active, 1); } /* * Initiate I/O on a vnode. */ void vn_strategy(struct vnode *vp, struct bio *bio) { struct bio_track *track; KKASSERT(bio->bio_buf->b_cmd != BUF_CMD_DONE); if (bio->bio_buf->b_cmd == BUF_CMD_READ) track = &vp->v_track_read; else track = &vp->v_track_write; bio->bio_track = track; atomic_add_int(&track->bk_active, 1); vop_strategy(*vp->v_ops, vp, bio); } /* * biodone: * * Finish I/O on a buffer, optionally calling a completion function. * This is usually called from an interrupt so process blocking is * not allowed. * * biodone is also responsible for setting B_CACHE in a B_VMIO bp. * In a non-VMIO bp, B_CACHE will be set on the next getblk() * assuming B_INVAL is clear. * * For the VMIO case, we set B_CACHE if the op was a read and no * read error occured, or if the op was a write. B_CACHE is never * set if the buffer is invalid or otherwise uncacheable. * * biodone does not mess with B_INVAL, allowing the I/O routine or the * initiator to leave B_INVAL set to brelse the buffer out of existance * in the biodone routine. */ void biodone(struct bio *bio) { struct buf *bp = bio->bio_buf; buf_cmd_t cmd; crit_enter(); KASSERT(BUF_REFCNTNB(bp) > 0, ("biodone: bp %p not busy %d", bp, BUF_REFCNTNB(bp))); KASSERT(bp->b_cmd != BUF_CMD_DONE, ("biodone: bp %p already done!", bp)); runningbufwakeup(bp); /* * Run up the chain of BIO's. Leave b_cmd intact for the duration. */ while (bio) { biodone_t *done_func; struct bio_track *track; /* * BIO tracking. Most but not all BIOs are tracked. */ if ((track = bio->bio_track) != NULL) { atomic_subtract_int(&track->bk_active, 1); if (track->bk_active < 0) { panic("biodone: bad active count bio %p\n", bio); } if (track->bk_waitflag) { track->bk_waitflag = 0; wakeup(track); } bio->bio_track = NULL; } /* * A bio_done function terminates the loop. The function * will be responsible for any further chaining and/or * buffer management. * * WARNING! The done function can deallocate the buffer! */ if ((done_func = bio->bio_done) != NULL) { bio->bio_done = NULL; done_func(bio); crit_exit(); return; } bio = bio->bio_prev; } cmd = bp->b_cmd; bp->b_cmd = BUF_CMD_DONE; /* * Only reads and writes are processed past this point. */ if (cmd != BUF_CMD_READ && cmd != BUF_CMD_WRITE) { brelse(bp); crit_exit(); return; } /* * Warning: softupdates may re-dirty the buffer. */ if (LIST_FIRST(&bp->b_dep) != NULL && bioops.io_complete) (*bioops.io_complete)(bp); if (bp->b_flags & B_VMIO) { int i; vm_ooffset_t foff; vm_page_t m; vm_object_t obj; int iosize; struct vnode *vp = bp->b_vp; obj = vp->v_object; #if defined(VFS_BIO_DEBUG) if (vp->v_holdcnt == 0) panic("biodone: zero vnode hold count"); if ((vp->v_flag & VOBJBUF) == 0) panic("biodone: vnode is not setup for merged cache"); #endif foff = bp->b_loffset; KASSERT(foff != NOOFFSET, ("biodone: no buffer offset")); KASSERT(obj != NULL, ("biodone: missing VM object")); #if defined(VFS_BIO_DEBUG) if (obj->paging_in_progress < bp->b_xio.xio_npages) { printf("biodone: paging in progress(%d) < bp->b_xio.xio_npages(%d)\n", obj->paging_in_progress, bp->b_xio.xio_npages); } #endif /* * Set B_CACHE if the op was a normal read and no error * occured. B_CACHE is set for writes in the b*write() * routines. */ iosize = bp->b_bcount - bp->b_resid; if (cmd == BUF_CMD_READ && (bp->b_flags & (B_INVAL|B_NOCACHE|B_ERROR)) == 0) { bp->b_flags |= B_CACHE; } for (i = 0; i < bp->b_xio.xio_npages; i++) { int bogusflag = 0; int resid; resid = ((foff + PAGE_SIZE) & ~(off_t)PAGE_MASK) - foff; if (resid > iosize) resid = iosize; /* * cleanup bogus pages, restoring the originals. Since * the originals should still be wired, we don't have * to worry about interrupt/freeing races destroying * the VM object association. */ m = bp->b_xio.xio_pages[i]; if (m == bogus_page) { bogusflag = 1; m = vm_page_lookup(obj, OFF_TO_IDX(foff)); if (m == NULL) panic("biodone: page disappeared"); bp->b_xio.xio_pages[i] = m; pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_xio.xio_pages, bp->b_xio.xio_npages); } #if defined(VFS_BIO_DEBUG) if (OFF_TO_IDX(foff) != m->pindex) { printf( "biodone: foff(%lu)/m->pindex(%d) mismatch\n", (unsigned long)foff, m->pindex); } #endif /* * In the write case, the valid and clean bits are * already changed correctly ( see bdwrite() ), so we * only need to do this here in the read case. */ if (cmd == BUF_CMD_READ && !bogusflag && resid > 0) { vfs_page_set_valid(bp, foff, i, m); } vm_page_flag_clear(m, PG_ZERO); /* * when debugging new filesystems or buffer I/O methods, this * is the most common error that pops up. if you see this, you * have not set the page busy flag correctly!!! */ if (m->busy == 0) { printf("biodone: page busy < 0, " "pindex: %d, foff: 0x(%x,%x), " "resid: %d, index: %d\n", (int) m->pindex, (int)(foff >> 32), (int) foff & 0xffffffff, resid, i); if (!vn_isdisk(vp, NULL)) printf(" iosize: %ld, loffset: %lld, flags: 0x%08x, npages: %d\n", bp->b_vp->v_mount->mnt_stat.f_iosize, bp->b_loffset, bp->b_flags, bp->b_xio.xio_npages); else printf(" VDEV, loffset: %lld, flags: 0x%08x, npages: %d\n", bp->b_loffset, bp->b_flags, bp->b_xio.xio_npages); printf(" valid: 0x%x, dirty: 0x%x, wired: %d\n", m->valid, m->dirty, m->wire_count); panic("biodone: page busy < 0"); } vm_page_io_finish(m); vm_object_pip_subtract(obj, 1); foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; iosize -= resid; } if (obj) vm_object_pip_wakeupn(obj, 0); } /* * For asynchronous completions, release the buffer now. The brelse * will do a wakeup there if necessary - so no need to do a wakeup * here in the async case. The sync case always needs to do a wakeup. */ if (bp->b_flags & B_ASYNC) { if ((bp->b_flags & (B_NOCACHE | B_INVAL | B_ERROR | B_RELBUF)) != 0) brelse(bp); else bqrelse(bp); } else { wakeup(bp); } crit_exit(); } /* * vfs_unbusy_pages: * * This routine is called in lieu of iodone in the case of * incomplete I/O. This keeps the busy status for pages * consistant. */ void vfs_unbusy_pages(struct buf *bp) { int i; runningbufwakeup(bp); if (bp->b_flags & B_VMIO) { struct vnode *vp = bp->b_vp; vm_object_t obj; obj = vp->v_object; for (i = 0; i < bp->b_xio.xio_npages; i++) { vm_page_t m = bp->b_xio.xio_pages[i]; /* * When restoring bogus changes the original pages * should still be wired, so we are in no danger of * losing the object association and do not need * critical section protection particularly. */ if (m == bogus_page) { m = vm_page_lookup(obj, OFF_TO_IDX(bp->b_loffset) + i); if (!m) { panic("vfs_unbusy_pages: page missing"); } bp->b_xio.xio_pages[i] = m; pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_xio.xio_pages, bp->b_xio.xio_npages); } vm_object_pip_subtract(obj, 1); vm_page_flag_clear(m, PG_ZERO); vm_page_io_finish(m); } vm_object_pip_wakeupn(obj, 0); } } /* * vfs_page_set_valid: * * Set the valid bits in a page based on the supplied offset. The * range is restricted to the buffer's size. * * This routine is typically called after a read completes. */ static void vfs_page_set_valid(struct buf *bp, vm_ooffset_t off, int pageno, vm_page_t m) { vm_ooffset_t soff, eoff; /* * Start and end offsets in buffer. eoff - soff may not cross a * page boundry or cross the end of the buffer. The end of the * buffer, in this case, is our file EOF, not the allocation size * of the buffer. */ soff = off; eoff = (off + PAGE_SIZE) & ~(off_t)PAGE_MASK; if (eoff > bp->b_loffset + bp->b_bcount) eoff = bp->b_loffset + bp->b_bcount; /* * Set valid range. This is typically the entire buffer and thus the * entire page. */ if (eoff > soff) { vm_page_set_validclean( m, (vm_offset_t) (soff & PAGE_MASK), (vm_offset_t) (eoff - soff) ); } } /* * vfs_busy_pages: * * This routine is called before a device strategy routine. * It is used to tell the VM system that paging I/O is in * progress, and treat the pages associated with the buffer * almost as being PG_BUSY. Also the object 'paging_in_progress' * flag is handled to make sure that the object doesn't become * inconsistant. * * Since I/O has not been initiated yet, certain buffer flags * such as B_ERROR or B_INVAL may be in an inconsistant state * and should be ignored. */ void vfs_busy_pages(struct vnode *vp, struct buf *bp) { int i, bogus; struct proc *p = curthread->td_proc; /* * The buffer's I/O command must already be set. If reading, * B_CACHE must be 0 (double check against callers only doing * I/O when B_CACHE is 0). */ KKASSERT(bp->b_cmd != BUF_CMD_DONE); KKASSERT(bp->b_cmd == BUF_CMD_WRITE || (bp->b_flags & B_CACHE) == 0); if (bp->b_flags & B_VMIO) { vm_object_t obj; vm_ooffset_t foff; obj = vp->v_object; foff = bp->b_loffset; KASSERT(bp->b_loffset != NOOFFSET, ("vfs_busy_pages: no buffer offset")); vfs_setdirty(bp); retry: for (i = 0; i < bp->b_xio.xio_npages; i++) { vm_page_t m = bp->b_xio.xio_pages[i]; if (vm_page_sleep_busy(m, FALSE, "vbpage")) goto retry; } bogus = 0; for (i = 0; i < bp->b_xio.xio_npages; i++) { vm_page_t m = bp->b_xio.xio_pages[i]; vm_page_flag_clear(m, PG_ZERO); if ((bp->b_flags & B_CLUSTER) == 0) { vm_object_pip_add(obj, 1); vm_page_io_start(m); } /* * When readying a vnode-backed buffer for a write * we must zero-fill any invalid portions of the * backing VM pages. * * When readying a vnode-backed buffer for a read * we must replace any dirty pages with a bogus * page so we do not destroy dirty data when * filling in gaps. Dirty pages might not * necessarily be marked dirty yet, so use m->valid * as a reasonable test. * * Bogus page replacement is, uh, bogus. We need * to find a better way. */ vm_page_protect(m, VM_PROT_NONE); if (bp->b_cmd == BUF_CMD_WRITE) { vfs_page_set_valid(bp, foff, i, m); } else if (m->valid == VM_PAGE_BITS_ALL) { bp->b_xio.xio_pages[i] = bogus_page; bogus++; } foff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; } if (bogus) pmap_qenter(trunc_page((vm_offset_t)bp->b_data), bp->b_xio.xio_pages, bp->b_xio.xio_npages); } /* * This is the easiest place to put the process accounting for the I/O * for now. */ if (p != NULL) { if (bp->b_cmd == BUF_CMD_READ) p->p_stats->p_ru.ru_inblock++; else p->p_stats->p_ru.ru_oublock++; } } /* * vfs_clean_pages: * * Tell the VM system that the pages associated with this buffer * are clean. This is used for delayed writes where the data is * going to go to disk eventually without additional VM intevention. * * Note that while we only really need to clean through to b_bcount, we * just go ahead and clean through to b_bufsize. */ static void vfs_clean_pages(struct buf *bp) { int i; if (bp->b_flags & B_VMIO) { vm_ooffset_t foff; foff = bp->b_loffset; KASSERT(foff != NOOFFSET, ("vfs_clean_pages: no buffer offset")); for (i = 0; i < bp->b_xio.xio_npages; i++) { vm_page_t m = bp->b_xio.xio_pages[i]; vm_ooffset_t noff = (foff + PAGE_SIZE) & ~(off_t)PAGE_MASK; vm_ooffset_t eoff = noff; if (eoff > bp->b_loffset + bp->b_bufsize) eoff = bp->b_loffset + bp->b_bufsize; vfs_page_set_valid(bp, foff, i, m); /* vm_page_clear_dirty(m, foff & PAGE_MASK, eoff - foff); */ foff = noff; } } } /* * vfs_bio_set_validclean: * * Set the range within the buffer to valid and clean. The range is * relative to the beginning of the buffer, b_loffset. Note that * b_loffset itself may be offset from the beginning of the first page. */ void vfs_bio_set_validclean(struct buf *bp, int base, int size) { if (bp->b_flags & B_VMIO) { int i; int n; /* * Fixup base to be relative to beginning of first page. * Set initial n to be the maximum number of bytes in the * first page that can be validated. */ base += (bp->b_loffset & PAGE_MASK); n = PAGE_SIZE - (base & PAGE_MASK); for (i = base / PAGE_SIZE; size > 0 && i < bp->b_xio.xio_npages; ++i) { vm_page_t m = bp->b_xio.xio_pages[i]; if (n > size) n = size; vm_page_set_validclean(m, base & PAGE_MASK, n); base += n; size -= n; n = PAGE_SIZE; } } } /* * vfs_bio_clrbuf: * * Clear a buffer. This routine essentially fakes an I/O, so we need * to clear B_ERROR and B_INVAL. * * Note that while we only theoretically need to clear through b_bcount, * we go ahead and clear through b_bufsize. */ void vfs_bio_clrbuf(struct buf *bp) { int i, mask = 0; caddr_t sa, ea; if ((bp->b_flags & (B_VMIO | B_MALLOC)) == B_VMIO) { bp->b_flags &= ~(B_INVAL|B_ERROR); if ((bp->b_xio.xio_npages == 1) && (bp->b_bufsize < PAGE_SIZE) && (bp->b_loffset & PAGE_MASK) == 0) { mask = (1 << (bp->b_bufsize / DEV_BSIZE)) - 1; if ((bp->b_xio.xio_pages[0]->valid & mask) == mask) { bp->b_resid = 0; return; } if (((bp->b_xio.xio_pages[0]->flags & PG_ZERO) == 0) && ((bp->b_xio.xio_pages[0]->valid & mask) == 0)) { bzero(bp->b_data, bp->b_bufsize); bp->b_xio.xio_pages[0]->valid |= mask; bp->b_resid = 0; return; } } ea = sa = bp->b_data; for(i=0;ib_xio.xio_npages;i++,sa=ea) { int j = ((vm_offset_t)sa & PAGE_MASK) / DEV_BSIZE; ea = (caddr_t)trunc_page((vm_offset_t)sa + PAGE_SIZE); ea = (caddr_t)(vm_offset_t)ulmin( (u_long)(vm_offset_t)ea, (u_long)(vm_offset_t)bp->b_data + bp->b_bufsize); mask = ((1 << ((ea - sa) / DEV_BSIZE)) - 1) << j; if ((bp->b_xio.xio_pages[i]->valid & mask) == mask) continue; if ((bp->b_xio.xio_pages[i]->valid & mask) == 0) { if ((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) { bzero(sa, ea - sa); } } else { for (; sa < ea; sa += DEV_BSIZE, j++) { if (((bp->b_xio.xio_pages[i]->flags & PG_ZERO) == 0) && (bp->b_xio.xio_pages[i]->valid & (1<b_xio.xio_pages[i]->valid |= mask; vm_page_flag_clear(bp->b_xio.xio_pages[i], PG_ZERO); } bp->b_resid = 0; } else { clrbuf(bp); } } /* * vm_hold_load_pages: * * Load pages into the buffer's address space. The pages are * allocated from the kernel object in order to reduce interference * with the any VM paging I/O activity. The range of loaded * pages will be wired. * * If a page cannot be allocated, the 'pagedaemon' is woken up to * retrieve the full range (to - from) of pages. * */ void vm_hold_load_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) { vm_offset_t pg; vm_page_t p; int index; to = round_page(to); from = round_page(from); index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; for (pg = from; pg < to; pg += PAGE_SIZE, index++) { tryagain: /* * Note: must allocate system pages since blocking here * could intefere with paging I/O, no matter which * process we are. */ p = vm_page_alloc(kernel_object, ((pg - VM_MIN_KERNEL_ADDRESS) >> PAGE_SHIFT), VM_ALLOC_NORMAL | VM_ALLOC_SYSTEM); if (!p) { vm_pageout_deficit += (to - from) >> PAGE_SHIFT; vm_wait(); goto tryagain; } vm_page_wire(p); p->valid = VM_PAGE_BITS_ALL; vm_page_flag_clear(p, PG_ZERO); pmap_kenter(pg, VM_PAGE_TO_PHYS(p)); bp->b_xio.xio_pages[index] = p; vm_page_wakeup(p); } bp->b_xio.xio_npages = index; } /* * vm_hold_free_pages: * * Return pages associated with the buffer back to the VM system. * * The range of pages underlying the buffer's address space will * be unmapped and un-wired. */ void vm_hold_free_pages(struct buf *bp, vm_offset_t from, vm_offset_t to) { vm_offset_t pg; vm_page_t p; int index, newnpages; from = round_page(from); to = round_page(to); newnpages = index = (from - trunc_page((vm_offset_t)bp->b_data)) >> PAGE_SHIFT; for (pg = from; pg < to; pg += PAGE_SIZE, index++) { p = bp->b_xio.xio_pages[index]; if (p && (index < bp->b_xio.xio_npages)) { if (p->busy) { printf("vm_hold_free_pages: doffset: %lld, loffset: %lld\n", bp->b_bio2.bio_offset, bp->b_loffset); } bp->b_xio.xio_pages[index] = NULL; pmap_kremove(pg); vm_page_busy(p); vm_page_unwire(p, 0); vm_page_free(p); } } bp->b_xio.xio_npages = newnpages; } /* * vmapbuf: * * Map a user buffer into KVM via a pbuf. On return the buffer's * b_data, b_bufsize, and b_bcount will be set, and its XIO page array * initialized. */ int vmapbuf(struct buf *bp, caddr_t udata, int bytes) { caddr_t addr; vm_paddr_t pa; int pidx; int i; int vmprot; struct vm_page *m; /* * bp had better have a command and it better be a pbuf. */ KKASSERT(bp->b_cmd != BUF_CMD_DONE); KKASSERT(bp->b_flags & B_PAGING); if (bytes < 0) return (-1); /* * Map the user data into KVM. Mappings have to be page-aligned. */ addr = (caddr_t)trunc_page((vm_offset_t)udata); pidx = 0; vmprot = VM_PROT_READ; if (bp->b_cmd == BUF_CMD_READ) vmprot |= VM_PROT_WRITE; while (addr < udata + bytes) { /* * Do the vm_fault if needed; do the copy-on-write thing * when reading stuff off device into memory. */ retry: if (addr >= udata) i = vm_fault_quick(addr, vmprot); else i = vm_fault_quick(udata, vmprot); if (i < 0) { for (i = 0; i < pidx; ++i) { vm_page_unhold(bp->b_xio.xio_pages[i]); bp->b_xio.xio_pages[i] = NULL; } return(-1); } /* * Extract from current process's address map. Since the * fault succeeded, an empty page indicates a race. */ pa = pmap_extract(&curproc->p_vmspace->vm_pmap, (vm_offset_t)addr); if (pa == 0) { printf("vmapbuf: warning, race against user address during I/O"); goto retry; } m = PHYS_TO_VM_PAGE(pa); vm_page_hold(m); bp->b_xio.xio_pages[pidx] = m; addr += PAGE_SIZE; ++pidx; } /* * Map the page array and set the buffer fields to point to * the mapped data buffer. */ if (pidx > btoc(MAXPHYS)) panic("vmapbuf: mapped more than MAXPHYS"); pmap_qenter((vm_offset_t)bp->b_kvabase, bp->b_xio.xio_pages, pidx); bp->b_xio.xio_npages = pidx; bp->b_data = bp->b_kvabase + ((int)(intptr_t)udata & PAGE_MASK); bp->b_bcount = bytes; bp->b_bufsize = bytes; return(0); } /* * vunmapbuf: * * Free the io map PTEs associated with this IO operation. * We also invalidate the TLB entries and restore the original b_addr. */ void vunmapbuf(struct buf *bp) { int pidx; int npages; KKASSERT(bp->b_flags & B_PAGING); npages = bp->b_xio.xio_npages; pmap_qremove(trunc_page((vm_offset_t)bp->b_data), npages); for (pidx = 0; pidx < npages; ++pidx) { vm_page_unhold(bp->b_xio.xio_pages[pidx]); bp->b_xio.xio_pages[pidx] = NULL; } bp->b_xio.xio_npages = 0; bp->b_data = bp->b_kvabase; } /* * Scan all buffers in the system and issue the callback. */ int scan_all_buffers(int (*callback)(struct buf *, void *), void *info) { int count = 0; int error; int n; for (n = 0; n < nbuf; ++n) { if ((error = callback(&buf[n], info)) < 0) { count = error; break; } count += error; } return (count); } /* * print out statistics from the current status of the buffer pool * this can be toggeled by the system control option debug.syncprt */ #ifdef DEBUG void vfs_bufstats(void) { int i, j, count; struct buf *bp; struct bqueues *dp; int counts[(MAXBSIZE / PAGE_SIZE) + 1]; static char *bname[3] = { "LOCKED", "LRU", "AGE" }; for (dp = bufqueues, i = 0; dp < &bufqueues[3]; dp++, i++) { count = 0; for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) counts[j] = 0; crit_enter(); TAILQ_FOREACH(bp, dp, b_freelist) { counts[bp->b_bufsize/PAGE_SIZE]++; count++; } crit_exit(); printf("%s: total-%d", bname[i], count); for (j = 0; j <= MAXBSIZE/PAGE_SIZE; j++) if (counts[j] != 0) printf(", %d-%d", j * PAGE_SIZE, counts[j]); printf("\n"); } } #endif #include "opt_ddb.h" #ifdef DDB #include DB_SHOW_COMMAND(buffer, db_show_buffer) { /* get args */ struct buf *bp = (struct buf *)addr; if (!have_addr) { db_printf("usage: show buffer \n"); return; } db_printf("b_flags = 0x%b\n", (u_int)bp->b_flags, PRINT_BUF_FLAGS); db_printf("b_cmd = %d\n", bp->b_cmd); db_printf("b_error = %d, b_bufsize = %d, b_bcount = %d, " "b_resid = %d\n, b_data = %p, " "bio_offset(disk) = %lld, bio_offset(phys) = %lld\n", bp->b_error, bp->b_bufsize, bp->b_bcount, bp->b_resid, bp->b_data, bp->b_bio2.bio_offset, (bp->b_bio2.bio_next ? bp->b_bio2.bio_next->bio_offset : (off_t)-1)); if (bp->b_xio.xio_npages) { int i; db_printf("b_xio.xio_npages = %d, pages(OBJ, IDX, PA): ", bp->b_xio.xio_npages); for (i = 0; i < bp->b_xio.xio_npages; i++) { vm_page_t m; m = bp->b_xio.xio_pages[i]; db_printf("(%p, 0x%lx, 0x%lx)", (void *)m->object, (u_long)m->pindex, (u_long)VM_PAGE_TO_PHYS(m)); if ((i + 1) < bp->b_xio.xio_npages) db_printf(","); } db_printf("\n"); } } #endif /* DDB */