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38 * @(#)buf.h 8.9 (Berkeley) 3/30/95
39 * $FreeBSD: src/sys/sys/buf.h,v 1.88.2.10 2003/01/25 19:02:23 dillon Exp $
40 * $DragonFly: src/sys/sys/buf.h,v 1.8 2004/02/16 19:09:31 dillon Exp $
47 #include <sys/queue.h>
52 #ifndef _SYS_DEVICE_H_
53 #include <sys/device.h>
61 * To avoid including <ufs/ffs/softdep.h>
63 LIST_HEAD(workhead, worklist);
65 * These are currently used only by the soft dependency code, hence
66 * are stored once in a global variable. If other subsystems wanted
67 * to use these hooks, a pointer to a set of bio_ops could be added
70 extern struct bio_ops {
71 void (*io_start) (struct buf *);
72 void (*io_complete) (struct buf *);
73 void (*io_deallocate) (struct buf *);
74 int (*io_fsync) (struct vnode *);
75 int (*io_sync) (struct mount *);
76 void (*io_movedeps) (struct buf *, struct buf *);
77 int (*io_countdeps) (struct buf *, int);
82 void (*ic_prev_iodone) (struct buf *);
83 void *ic_prev_iodone_chain;
91 * The buffer header describes an I/O operation in the kernel.
94 * b_bufsize, b_bcount. b_bufsize is the allocation size of the
95 * buffer, either DEV_BSIZE or PAGE_SIZE aligned. b_bcount is the
96 * originally requested buffer size and can serve as a bounds check
97 * against EOF. For most, but not all uses, b_bcount == b_bufsize.
99 * b_dirtyoff, b_dirtyend. Buffers support piecemeal, unaligned
100 * ranges of dirty data that need to be written to backing store.
101 * The range is typically clipped at b_bcount ( not b_bufsize ).
103 * b_resid. Number of bytes remaining in I/O. After an I/O operation
104 * completes, b_resid is usually 0 indicating 100% success.
107 LIST_ENTRY(buf) b_hash; /* Hash chain. */
108 TAILQ_ENTRY(buf) b_vnbufs; /* Buffer's associated vnode. */
109 TAILQ_ENTRY(buf) b_freelist; /* Free list position if not active. */
110 TAILQ_ENTRY(buf) b_act; /* Device driver queue when active. *new* */
111 long b_flags; /* B_* flags. */
112 unsigned short b_qindex; /* buffer queue index */
113 unsigned char b_xflags; /* extra flags */
114 struct lock b_lock; /* Buffer lock */
115 int b_error; /* Errno value. */
116 long b_bufsize; /* Allocated buffer size. */
117 long b_runningbufspace; /* when I/O is running, pipelining */
118 long b_bcount; /* Valid bytes in buffer. */
119 long b_resid; /* Remaining I/O. */
120 dev_t b_dev; /* Device associated with buffer. */
121 caddr_t b_data; /* Memory, superblocks, indirect etc. */
122 caddr_t b_kvabase; /* base kva for buffer */
123 int b_kvasize; /* size of kva for buffer */
124 daddr_t b_lblkno; /* Logical block number. */
125 daddr_t b_blkno; /* Underlying physical block number. */
126 off_t b_offset; /* Offset into file */
127 /* Function to call upon completion. */
128 void (*b_iodone) (struct buf *);
129 /* For nested b_iodone's. */
130 struct iodone_chain *b_iodone_chain;
131 struct vnode *b_vp; /* Device vnode. */
132 int b_dirtyoff; /* Offset in buffer of dirty region. */
133 int b_dirtyend; /* Offset of end of dirty region. */
134 daddr_t b_pblkno; /* physical block number */
135 void *b_saveaddr; /* Original b_addr for physio. */
136 void *b_driver1; /* for private use by the driver */
137 void *b_driver2; /* for private use by the driver */
138 void *b_caller1; /* for private use by the caller */
139 void *b_caller2; /* for private use by the caller */
145 TAILQ_HEAD(cluster_list_head, buf) cluster_head;
146 TAILQ_ENTRY(buf) cluster_entry;
148 struct vm_page *b_pages[btoc(MAXPHYS)];
150 struct workhead b_dep; /* List of filesystem dependencies. */
151 struct chain_info { /* buffer chaining */
157 #define b_spc b_pager.pg_spc
160 * These flags are kept in b_flags.
164 * B_ASYNC VOP calls on bp's are usually async whether or not
165 * B_ASYNC is set, but some subsystems, such as NFS, like
166 * to know what is best for the caller so they can
169 * B_PAGING Indicates that bp is being used by the paging system or
170 * some paging system and that the bp is not linked into
171 * the b_vp's clean/dirty linked lists or ref counts.
172 * Buffer vp reassignments are illegal in this case.
174 * B_CACHE This may only be set if the buffer is entirely valid.
175 * The situation where B_DELWRI is set and B_CACHE is
176 * clear MUST be committed to disk by getblk() so
177 * B_DELWRI can also be cleared. See the comments for
178 * getblk() in kern/vfs_bio.c. If B_CACHE is clear,
179 * the caller is expected to clear B_ERROR|B_INVAL,
180 * set B_READ, and initiate an I/O.
182 * The 'entire buffer' is defined to be the range from
183 * 0 through b_bcount.
185 * B_MALLOC Request that the buffer be allocated from the malloc
186 * pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned.
188 * B_CLUSTEROK This flag is typically set for B_DELWRI buffers
189 * by filesystems that allow clustering when the buffer
190 * is fully dirty and indicates that it may be clustered
191 * with other adjacent dirty buffers. Note the clustering
192 * may not be used with the stage 1 data write under NFS
193 * but may be used for the commit rpc portion.
195 * B_VMIO Indicates that the buffer is tied into an VM object.
196 * The buffer's data is always PAGE_SIZE aligned even
197 * if b_bufsize and b_bcount are not. ( b_bufsize is
198 * always at least DEV_BSIZE aligned, though ).
200 * B_DIRECT Hint that we should attempt to completely free
201 * the pages underlying the buffer. B_DIRECT is
202 * sticky until the buffer is released and typically
203 * only has an effect when B_RELBUF is also set.
205 * B_NOWDRAIN This flag should be set when a device (like VN)
206 * does a turn-around VOP_WRITE from its strategy
207 * routine. This flag prevents bwrite() from blocking
208 * in wdrain, avoiding a deadlock situation.
211 #define B_AGE 0x00000001 /* Move to age queue when I/O done. */
212 #define B_NEEDCOMMIT 0x00000002 /* Append-write in progress. */
213 #define B_ASYNC 0x00000004 /* Start I/O, do not wait. */
214 #define B_DIRECT 0x00000008 /* direct I/O flag (pls free vmio) */
215 #define B_DEFERRED 0x00000010 /* Skipped over for cleaning */
216 #define B_CACHE 0x00000020 /* Bread found us in the cache. */
217 #define B_CALL 0x00000040 /* Call b_iodone from biodone. */
218 #define B_DELWRI 0x00000080 /* Delay I/O until buffer reused. */
219 #define B_FREEBUF 0x00000100 /* Instruct driver: free blocks */
220 #define B_DONE 0x00000200 /* I/O completed. */
221 #define B_EINTR 0x00000400 /* I/O was interrupted */
222 #define B_ERROR 0x00000800 /* I/O error occurred. */
223 #define B_SCANNED 0x00001000 /* VOP_FSYNC funcs mark written bufs */
224 #define B_INVAL 0x00002000 /* Does not contain valid info. */
225 #define B_LOCKED 0x00004000 /* Locked in core (not reusable). */
226 #define B_NOCACHE 0x00008000 /* Do not cache block after use. */
227 #define B_MALLOC 0x00010000 /* malloced b_data */
228 #define B_CLUSTEROK 0x00020000 /* Pagein op, so swap() can count it. */
229 #define B_PHYS 0x00040000 /* I/O to user memory. */
230 #define B_RAW 0x00080000 /* Set by physio for raw transfers. */
231 #define B_READ 0x00100000 /* Read buffer. */
232 #define B_DIRTY 0x00200000 /* Needs writing later. */
233 #define B_RELBUF 0x00400000 /* Release VMIO buffer. */
234 #define B_WANT 0x00800000 /* Used by vm_pager.c */
235 #define B_WRITE 0x00000000 /* Write buffer (pseudo flag). */
236 #define B_WRITEINPROG 0x01000000 /* Write in progress. */
237 #define B_XXX 0x02000000 /* Debugging flag. */
238 #define B_PAGING 0x04000000 /* volatile paging I/O -- bypass VMIO */
239 #define B_ORDERED 0x08000000 /* Must guarantee I/O ordering */
240 #define B_RAM 0x10000000 /* Read ahead mark (flag) */
241 #define B_VMIO 0x20000000 /* VMIO flag */
242 #define B_CLUSTER 0x40000000 /* pagein op, so swap() can count it */
243 #define B_NOWDRAIN 0x80000000 /* Avoid wdrain deadlock */
245 #define PRINT_BUF_FLAGS "\20\40nowdrain\37cluster\36vmio\35ram\34ordered" \
246 "\33paging\32xxx\31writeinprog\30want\27relbuf\26dirty" \
247 "\25read\24raw\23phys\22clusterok\21malloc\20nocache" \
248 "\17locked\16inval\15scanned\14error\13eintr\12done\11freebuf" \
249 "\10delwri\7call\6cache\4direct\3async\2needcommit\1age"
252 * These flags are kept in b_xflags.
254 #define BX_VNDIRTY 0x00000001 /* On vnode dirty list */
255 #define BX_VNCLEAN 0x00000002 /* On vnode clean list */
256 #define BX_BKGRDWRITE 0x00000004 /* Do writes in background */
257 #define BX_BKGRDINPROG 0x00000008 /* Background write in progress */
258 #define BX_BKGRDWAIT 0x00000010 /* Background write waiting */
259 #define BX_AUTOCHAINDONE 0x00000020 /* pager I/O chain auto mode */
261 #define NOOFFSET (-1LL) /* No buffer offset calculated yet */
265 * Buffer locking. See sys/buf2.h for inline functions.
267 extern struct lwkt_token buftimetoken; /* Interlock on setting prio and timo */
268 extern char *buf_wmesg; /* Default buffer lock message */
269 #define BUF_WMESG "bufwait"
273 struct buf_queue_head {
274 TAILQ_HEAD(buf_queue, buf) queue;
276 struct buf *insert_point;
277 struct buf *switch_point;
281 * This structure describes a clustered I/O. It is stored in the b_saveaddr
282 * field of the buffer on which I/O is done. At I/O completion, cluster
283 * callback uses the structure to parcel I/O's to individual buffers, and
284 * then free's this structure.
286 struct cluster_save {
287 long bs_bcount; /* Saved b_bcount. */
288 long bs_bufsize; /* Saved b_bufsize. */
289 void *bs_saveaddr; /* Saved b_addr. */
290 int bs_nchildren; /* Number of associated buffers. */
291 struct buf **bs_children; /* List of associated buffers. */
295 * Definitions for the buffer free lists.
297 #define BUFFER_QUEUES 6 /* number of free buffer queues */
299 #define QUEUE_NONE 0 /* on no queue */
300 #define QUEUE_LOCKED 1 /* locked buffers */
301 #define QUEUE_CLEAN 2 /* non-B_DELWRI buffers */
302 #define QUEUE_DIRTY 3 /* B_DELWRI buffers */
303 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */
304 #define QUEUE_EMPTY 5 /* empty buffer headers */
307 * Zero out the buffer's data area.
309 #define clrbuf(bp) { \
310 bzero((bp)->b_data, (u_int)(bp)->b_bcount); \
315 * Flags to low-level bitmap allocation routines (balloc).
317 * Note: sequential_heuristic() in kern/vfs_vnops.c limits the count
320 #define B_SEQMASK 0x7F000000 /* Sequential heuristic mask. */
321 #define B_SEQSHIFT 24 /* Sequential heuristic shift. */
322 #define B_SEQMAX 0x7F
323 #define B_CLRBUF 0x01 /* Cleared invalid areas of buffer. */
324 #define B_SYNC 0x02 /* Do all allocations synchronously. */
327 extern int nbuf; /* The number of buffer headers */
328 extern int maxswzone; /* Max KVA for swap structures */
329 extern int maxbcache; /* Max KVA for buffer cache */
330 extern int runningbufspace;
331 extern int buf_maxio; /* nominal maximum I/O for buffer */
332 extern struct buf *buf; /* The buffer headers. */
333 extern char *buffers; /* The buffer contents. */
334 extern int bufpages; /* Number of memory pages in the buffer pool. */
335 extern struct buf *swbuf; /* Swap I/O buffer headers. */
336 extern int nswbuf; /* Number of swap I/O buffer headers. */
337 extern TAILQ_HEAD(swqueue, buf) bswlist;
338 extern TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES];
342 caddr_t bufhashinit (caddr_t);
344 void bwillwrite (void);
345 int buf_dirty_count_severe (void);
346 void bremfree (struct buf *);
347 int bread (struct vnode *, daddr_t, int, struct buf **);
348 int breadn (struct vnode *, daddr_t, int, daddr_t *, int *, int,
350 int bwrite (struct buf *);
351 void bdwrite (struct buf *);
352 void bawrite (struct buf *);
353 void bdirty (struct buf *);
354 void bundirty (struct buf *);
355 int bowrite (struct buf *);
356 void brelse (struct buf *);
357 void bqrelse (struct buf *);
358 int vfs_bio_awrite (struct buf *);
359 struct buf * getpbuf (int *);
360 struct buf *incore (struct vnode *, daddr_t);
361 struct buf *gbincore (struct vnode *, daddr_t);
362 int inmem (struct vnode *, daddr_t);
363 struct buf *getblk (struct vnode *, daddr_t, int, int, int);
364 struct buf *geteblk (int);
365 int biowait (struct buf *);
366 void biodone (struct buf *);
368 void cluster_callback (struct buf *);
369 int cluster_read (struct vnode *, u_quad_t, daddr_t, long,
370 long, int, struct buf **);
371 int cluster_wbuild (struct vnode *, long, daddr_t, int);
372 void cluster_write (struct buf *, u_quad_t, int);
373 int physio (dev_t dev, struct uio *uio, int ioflag);
374 #define physread physio
375 #define physwrite physio
376 void vfs_bio_set_validclean (struct buf *, int base, int size);
377 void vfs_bio_clrbuf (struct buf *);
378 void vfs_busy_pages (struct buf *, int clear_modify);
379 void vfs_unbusy_pages (struct buf *);
380 void vwakeup (struct buf *);
381 int vmapbuf (struct buf *);
382 void vunmapbuf (struct buf *);
383 void relpbuf (struct buf *, int *);
384 void brelvp (struct buf *);
385 void bgetvp (struct vnode *, struct buf *);
386 void pbgetvp (struct vnode *, struct buf *);
387 void pbrelvp (struct buf *);
388 int allocbuf (struct buf *bp, int size);
389 void reassignbuf (struct buf *, struct vnode *);
390 void pbreassignbuf (struct buf *, struct vnode *);
391 struct buf *trypbuf (int *);
395 #endif /* !_SYS_BUF_H_ */