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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 1.20 2005/08/12 00:17:26 hmp Exp $
47 #include <sys/queue.h>
52 #ifndef _SYS_DEVICE_H_
53 #include <sys/device.h>
73 RB_PROTOTYPE(buf_rb_tree, buf, b_rbnode, rb_buf_compare);
76 * To avoid including <ufs/ffs/softdep.h>
78 LIST_HEAD(workhead, worklist);
80 * These are currently used only by the soft dependency code, hence
81 * are stored once in a global variable. If other subsystems wanted
82 * to use these hooks, a pointer to a set of bio_ops could be added
85 extern struct bio_ops {
86 void (*io_start) (struct buf *);
87 void (*io_complete) (struct buf *);
88 void (*io_deallocate) (struct buf *);
89 int (*io_fsync) (struct vnode *);
90 int (*io_sync) (struct mount *);
91 void (*io_movedeps) (struct buf *, struct buf *);
92 int (*io_countdeps) (struct buf *, int);
97 void (*ic_prev_iodone) (struct buf *);
98 void *ic_prev_iodone_chain;
106 * The buffer header describes an I/O operation in the kernel.
109 * b_bufsize, b_bcount. b_bufsize is the allocation size of the
110 * buffer, either DEV_BSIZE or PAGE_SIZE aligned. b_bcount is the
111 * originally requested buffer size and can serve as a bounds check
112 * against EOF. For most, but not all uses, b_bcount == b_bufsize.
114 * b_dirtyoff, b_dirtyend. Buffers support piecemeal, unaligned
115 * ranges of dirty data that need to be written to backing store.
116 * The range is typically clipped at b_bcount ( not b_bufsize ).
118 * b_resid. Number of bytes remaining in I/O. After an I/O operation
119 * completes, b_resid is usually 0 indicating 100% success.
122 LIST_ENTRY(buf) b_hash; /* Hash chain. */
123 RB_ENTRY(buf) b_rbnode; /* Red-Black node in vnode RB tree */
124 TAILQ_ENTRY(buf) b_freelist; /* Free list position if not active. */
125 TAILQ_ENTRY(buf) b_act; /* driver queue when active. *new* */
126 struct bio b_bio; /* Underlying I/O */
127 long b_flags; /* B_* flags. */
128 unsigned short b_qindex; /* buffer queue index */
129 unsigned char b_xflags; /* extra flags */
130 struct lock b_lock; /* Buffer lock */
131 long b_bufsize; /* Allocated buffer size. */
132 long b_runningbufspace; /* when I/O is running, pipelining */
133 long b_bcount; /* Valid bytes in buffer. */
134 caddr_t b_data; /* Memory, superblocks, indirect etc. */
135 caddr_t b_kvabase; /* base kva for buffer */
136 int b_kvasize; /* size of kva for buffer */
137 daddr_t b_lblkno; /* Logical block number. */
138 off_t b_offset; /* Offset into file */
139 /* For nested b_iodone's. */
140 struct iodone_chain *b_iodone_chain;
141 struct vnode *b_vp; /* Device vnode. */
142 int b_dirtyoff; /* Offset in buffer of dirty region. */
143 int b_dirtyend; /* Offset of end of dirty region. */
144 void *b_saveaddr; /* Original b_addr for physio. */
150 TAILQ_HEAD(cluster_list_head, buf) cluster_head;
151 TAILQ_ENTRY(buf) cluster_entry;
153 struct xio b_xio; /* page list management for buffer head. */
154 struct workhead b_dep; /* List of filesystem dependencies. */
155 struct chain_info { /* buffer chaining */
161 #define b_dev b_bio.bio_dev
162 #define b_resid b_bio.bio_resid
163 #define b_error b_bio.bio_error
164 #define b_blkno b_bio.bio_blkno
165 #define b_pblkno b_bio.bio_pblkno
166 #define b_driver1 b_bio.bio_driver_ctx
167 #define b_caller1 b_bio.bio_caller_ctx
168 #define b_iodone b_bio.bio_done
169 #define b_spc b_pager.pg_spc
172 * These flags are kept in b_flags.
176 * B_ASYNC VOP calls on bp's are usually async whether or not
177 * B_ASYNC is set, but some subsystems, such as NFS, like
178 * to know what is best for the caller so they can
181 * B_PAGING Indicates that bp is being used by the paging system or
182 * some paging system and that the bp is not linked into
183 * the b_vp's clean/dirty linked lists or ref counts.
184 * Buffer vp reassignments are illegal in this case.
186 * B_CACHE This may only be set if the buffer is entirely valid.
187 * The situation where B_DELWRI is set and B_CACHE is
188 * clear MUST be committed to disk by getblk() so
189 * B_DELWRI can also be cleared. See the comments for
190 * getblk() in kern/vfs_bio.c. If B_CACHE is clear,
191 * the caller is expected to clear B_ERROR|B_INVAL,
192 * set B_READ, and initiate an I/O.
194 * The 'entire buffer' is defined to be the range from
195 * 0 through b_bcount.
197 * B_MALLOC Request that the buffer be allocated from the malloc
198 * pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned.
200 * B_CLUSTEROK This flag is typically set for B_DELWRI buffers
201 * by filesystems that allow clustering when the buffer
202 * is fully dirty and indicates that it may be clustered
203 * with other adjacent dirty buffers. Note the clustering
204 * may not be used with the stage 1 data write under NFS
205 * but may be used for the commit rpc portion.
207 * B_VMIO Indicates that the buffer is tied into an VM object.
208 * The buffer's data is always PAGE_SIZE aligned even
209 * if b_bufsize and b_bcount are not. ( b_bufsize is
210 * always at least DEV_BSIZE aligned, though ).
212 * B_DIRECT Hint that we should attempt to completely free
213 * the pages underlying the buffer. B_DIRECT is
214 * sticky until the buffer is released and typically
215 * only has an effect when B_RELBUF is also set.
217 * B_NOWDRAIN This flag should be set when a device (like VN)
218 * does a turn-around VOP_WRITE from its strategy
219 * routine. This flag prevents bwrite() from blocking
220 * in wdrain, avoiding a deadlock situation.
223 #define B_AGE 0x00000001 /* Move to age queue when I/O done. */
224 #define B_NEEDCOMMIT 0x00000002 /* Append-write in progress. */
225 #define B_ASYNC 0x00000004 /* Start I/O, do not wait. */
226 #define B_DIRECT 0x00000008 /* direct I/O flag (pls free vmio) */
227 #define B_DEFERRED 0x00000010 /* Skipped over for cleaning */
228 #define B_CACHE 0x00000020 /* Bread found us in the cache. */
229 #define B_UNUSED40 0x00000040 /* Unused */
230 #define B_DELWRI 0x00000080 /* Delay I/O until buffer reused. */
231 #define B_FREEBUF 0x00000100 /* Instruct driver: free blocks */
232 #define B_DONE 0x00000200 /* I/O completed. */
233 #define B_EINTR 0x00000400 /* I/O was interrupted */
234 #define B_ERROR 0x00000800 /* I/O error occurred. */
235 #define B_UNUSED1000 0x00001000 /* Unused */
236 #define B_INVAL 0x00002000 /* Does not contain valid info. */
237 #define B_LOCKED 0x00004000 /* Locked in core (not reusable). */
238 #define B_NOCACHE 0x00008000 /* Do not cache block after use. */
239 #define B_MALLOC 0x00010000 /* malloced b_data */
240 #define B_CLUSTEROK 0x00020000 /* Pagein op, so swap() can count it. */
241 #define B_PHYS 0x00040000 /* I/O to user memory. */
242 #define B_RAW 0x00080000 /* Set by physio for raw transfers. */
243 #define B_READ 0x00100000 /* Read buffer. */
244 #define B_DIRTY 0x00200000 /* Needs writing later. */
245 #define B_RELBUF 0x00400000 /* Release VMIO buffer. */
246 #define B_WANT 0x00800000 /* Used by vm_pager.c */
247 #define B_WRITE 0x00000000 /* Write buffer (pseudo flag). */
248 #define B_UNUSED1000000 0x01000000 /* Unused */
249 #define B_XXX 0x02000000 /* Debugging flag. */
250 #define B_PAGING 0x04000000 /* volatile paging I/O -- bypass VMIO */
251 #define B_ORDERED 0x08000000 /* Must guarantee I/O ordering */
252 #define B_RAM 0x10000000 /* Read ahead mark (flag) */
253 #define B_VMIO 0x20000000 /* VMIO flag */
254 #define B_CLUSTER 0x40000000 /* pagein op, so swap() can count it */
255 #define B_NOWDRAIN 0x80000000 /* Avoid wdrain deadlock */
257 #define PRINT_BUF_FLAGS "\20\40nowdrain\37cluster\36vmio\35ram\34ordered" \
258 "\33paging\32xxx\31writeinprog\30want\27relbuf\26dirty" \
259 "\25read\24raw\23phys\22clusterok\21malloc\20nocache" \
260 "\17locked\16inval\15scanned\14error\13eintr\12done\11freebuf" \
261 "\10delwri\7call\6cache\4direct\3async\2needcommit\1age"
264 * These flags are kept in b_xflags.
266 #define BX_VNDIRTY 0x00000001 /* On vnode dirty list */
267 #define BX_VNCLEAN 0x00000002 /* On vnode clean list */
268 #define BX_BKGRDWRITE 0x00000004 /* Do writes in background */
269 #define BX_BKGRDINPROG 0x00000008 /* Background write in progress */
270 #define BX_BKGRDWAIT 0x00000010 /* Background write waiting */
271 #define BX_AUTOCHAINDONE 0x00000020 /* pager I/O chain auto mode */
273 #define NOOFFSET (-1LL) /* No buffer offset calculated yet */
277 * Buffer locking. See sys/buf2.h for inline functions.
279 extern struct lwkt_token buftimetoken; /* Interlock on setting prio and timo */
280 extern char *buf_wmesg; /* Default buffer lock message */
281 #define BUF_WMESG "bufwait"
285 struct buf_queue_head {
286 TAILQ_HEAD(buf_queue, buf) queue;
288 struct buf *insert_point;
289 struct buf *switch_point;
293 * This structure describes a clustered I/O. It is stored in the b_saveaddr
294 * field of the buffer on which I/O is done. At I/O completion, cluster
295 * callback uses the structure to parcel I/O's to individual buffers, and
296 * then free's this structure.
298 struct cluster_save {
299 long bs_bcount; /* Saved b_bcount. */
300 long bs_bufsize; /* Saved b_bufsize. */
301 void *bs_saveaddr; /* Saved b_addr. */
302 int bs_nchildren; /* Number of associated buffers. */
303 struct buf **bs_children; /* List of associated buffers. */
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. */
340 caddr_t bufhashinit (caddr_t);
342 void bwillwrite (void);
343 int buf_dirty_count_severe (void);
344 void bremfree (struct buf *);
345 int bread (struct vnode *, daddr_t, int, struct buf **);
346 int breadn (struct vnode *, daddr_t, int, daddr_t *, int *, int,
348 int bwrite (struct buf *);
349 void bdwrite (struct buf *);
350 void bawrite (struct buf *);
351 void bdirty (struct buf *);
352 void bundirty (struct buf *);
353 int bowrite (struct buf *);
354 void brelse (struct buf *);
355 void bqrelse (struct buf *);
356 int vfs_bio_awrite (struct buf *);
357 struct buf * getpbuf (int *);
358 struct buf *incore (struct vnode *, daddr_t);
359 struct buf *gbincore (struct vnode *, daddr_t);
360 int inmem (struct vnode *, daddr_t);
361 struct buf *getblk (struct vnode *, daddr_t, int, int, int);
362 struct buf *geteblk (int);
363 int biowait (struct buf *);
364 void biodone (struct buf *);
366 void cluster_callback (struct buf *);
367 int cluster_read (struct vnode *, u_quad_t, daddr_t, long,
368 long, int, struct buf **);
369 int cluster_wbuild (struct vnode *, long, daddr_t, int);
370 void cluster_write (struct buf *, u_quad_t, int);
371 int physio (dev_t dev, struct uio *uio, int ioflag);
372 #define physread physio
373 #define physwrite physio
374 void vfs_bio_set_validclean (struct buf *, int base, int size);
375 void vfs_bio_clrbuf (struct buf *);
376 void vfs_busy_pages (struct buf *, int clear_modify);
377 void vfs_unbusy_pages (struct buf *);
378 void vwakeup (struct buf *);
379 int vmapbuf (struct buf *);
380 void vunmapbuf (struct buf *);
381 void relpbuf (struct buf *, int *);
382 void brelvp (struct buf *);
383 void bgetvp (struct vnode *, struct buf *);
384 void pbgetvp (struct vnode *, struct buf *);
385 void pbrelvp (struct buf *);
386 int allocbuf (struct buf *bp, int size);
387 void reassignbuf (struct buf *, struct vnode *);
388 void pbreassignbuf (struct buf *, struct vnode *);
389 struct buf *trypbuf (int *);
393 #endif /* !_SYS_BUF_H_ */