2 * SPDX-License-Identifier: BSD-3-Clause
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36 * @(#)buf.h 8.9 (Berkeley) 3/30/95
43 #include <sys/bufobj.h>
44 #include <sys/queue.h>
46 #include <sys/lockmgr.h>
57 * To avoid including <ufs/ffs/softdep.h>
59 LIST_HEAD(workhead, worklist);
61 * These are currently used only by the soft dependency code, hence
62 * are stored once in a global variable. If other subsystems wanted
63 * to use these hooks, a pointer to a set of bio_ops could be added
66 extern struct bio_ops {
67 void (*io_start)(struct buf *);
68 void (*io_complete)(struct buf *);
69 void (*io_deallocate)(struct buf *);
70 int (*io_countdeps)(struct buf *, int);
76 typedef uint32_t b_xflags_t;
79 * The buffer header describes an I/O operation in the kernel.
82 * b_bufsize, b_bcount. b_bufsize is the allocation size of the
83 * buffer, either DEV_BSIZE or PAGE_SIZE aligned. b_bcount is the
84 * originally requested buffer size and can serve as a bounds check
85 * against EOF. For most, but not all uses, b_bcount == b_bufsize.
87 * b_dirtyoff, b_dirtyend. Buffers support piecemeal, unaligned
88 * ranges of dirty data that need to be written to backing store.
89 * The range is typically clipped at b_bcount ( not b_bufsize ).
91 * b_resid. Number of bytes remaining in I/O. After an I/O operation
92 * completes, b_resid is usually 0 indicating 100% success.
94 * All fields are protected by the buffer lock except those marked:
95 * V - Protected by owning bufobj lock
96 * Q - Protected by the buf queue lock
97 * D - Protected by an dependency implementation specific lock
100 struct bufobj *b_bufobj;
105 uint16_t b_iocmd; /* BIO_* bio_cmd from bio.h */
106 uint16_t b_ioflags; /* BIO_* bio_flags from bio.h */
109 void (*b_iodone)(struct buf *);
110 void (*b_ckhashcalc)(struct buf *);
111 uint64_t b_ckhash; /* B_CKHASH requested check-hash */
112 daddr_t b_blkno; /* Underlying physical block number. */
113 off_t b_offset; /* Offset into file. */
114 TAILQ_ENTRY(buf) b_bobufs; /* (V) Buffer's associated vnode. */
115 uint32_t b_vflags; /* (V) BV_* flags */
116 uint8_t b_qindex; /* (Q) buffer queue index */
117 uint8_t b_domain; /* (Q) buf domain this resides in */
118 uint16_t b_subqueue; /* (Q) per-cpu q if any */
119 uint32_t b_flags; /* B_* flags. */
120 b_xflags_t b_xflags; /* extra flags */
121 struct lock b_lock; /* Buffer lock */
122 long b_bufsize; /* Allocated buffer size. */
123 int b_runningbufspace; /* when I/O is running, pipelining */
124 int b_kvasize; /* size of kva for buffer */
125 int b_dirtyoff; /* Offset in buffer of dirty region. */
126 int b_dirtyend; /* Offset of end of dirty region. */
127 caddr_t b_kvabase; /* base kva for buffer */
128 daddr_t b_lblkno; /* Logical block number. */
129 struct vnode *b_vp; /* Device vnode. */
130 struct ucred *b_rcred; /* Read credentials reference. */
131 struct ucred *b_wcred; /* Write credentials reference. */
133 TAILQ_ENTRY(buf) b_freelist; /* (Q) */
135 void (*b_pgiodone)(void *, vm_page_t *, int, int);
141 TAILQ_HEAD(cluster_list_head, buf) cluster_head;
142 TAILQ_ENTRY(buf) cluster_entry;
145 struct workhead b_dep; /* (D) List of filesystem dependencies. */
150 #if defined(FULL_BUF_TRACKING)
151 #define BUF_TRACKING_SIZE 32
152 #define BUF_TRACKING_ENTRY(x) ((x) & (BUF_TRACKING_SIZE - 1))
153 const char *b_io_tracking[BUF_TRACKING_SIZE];
155 #elif defined(BUF_TRACKING)
156 const char *b_io_tracking;
158 struct vm_page *b_pages[];
161 #define b_object b_bufobj->bo_object
164 * These flags are kept in b_flags.
168 * B_ASYNC VOP calls on bp's are usually async whether or not
169 * B_ASYNC is set, but some subsystems, such as NFS, like
170 * to know what is best for the caller so they can
173 * B_PAGING Indicates that bp is being used by the paging system or
174 * some paging system and that the bp is not linked into
175 * the b_vp's clean/dirty linked lists or ref counts.
176 * Buffer vp reassignments are illegal in this case.
178 * B_CACHE This may only be set if the buffer is entirely valid.
179 * The situation where B_DELWRI is set and B_CACHE is
180 * clear MUST be committed to disk by getblk() so
181 * B_DELWRI can also be cleared. See the comments for
182 * getblk() in kern/vfs_bio.c. If B_CACHE is clear,
183 * the caller is expected to clear BIO_ERROR and B_INVAL,
184 * set BIO_READ, and initiate an I/O.
186 * The 'entire buffer' is defined to be the range from
187 * 0 through b_bcount.
189 * B_MALLOC Request that the buffer be allocated from the malloc
190 * pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned.
192 * B_CLUSTEROK This flag is typically set for B_DELWRI buffers
193 * by filesystems that allow clustering when the buffer
194 * is fully dirty and indicates that it may be clustered
195 * with other adjacent dirty buffers. Note the clustering
196 * may not be used with the stage 1 data write under NFS
197 * but may be used for the commit rpc portion.
199 * B_INVALONERR This flag is set on dirty buffers. It specifies that a
200 * write error should forcibly invalidate the buffer
201 * contents. This flag should be used with caution, as it
202 * discards data. It is incompatible with B_ASYNC.
204 * B_VMIO Indicates that the buffer is tied into an VM object.
205 * The buffer's data is always PAGE_SIZE aligned even
206 * if b_bufsize and b_bcount are not. ( b_bufsize is
207 * always at least DEV_BSIZE aligned, though ).
209 * B_DIRECT Hint that we should attempt to completely free
210 * the pages underlying the buffer. B_DIRECT is
211 * sticky until the buffer is released and typically
212 * only has an effect when B_RELBUF is also set.
216 #define B_AGE 0x00000001 /* Move to age queue when I/O done. */
217 #define B_NEEDCOMMIT 0x00000002 /* Append-write in progress. */
218 #define B_ASYNC 0x00000004 /* Start I/O, do not wait. */
219 #define B_DIRECT 0x00000008 /* direct I/O flag (pls free vmio) */
220 #define B_DEFERRED 0x00000010 /* Skipped over for cleaning */
221 #define B_CACHE 0x00000020 /* Bread found us in the cache. */
222 #define B_VALIDSUSPWRT 0x00000040 /* Valid write during suspension. */
223 #define B_DELWRI 0x00000080 /* Delay I/O until buffer reused. */
224 #define B_CKHASH 0x00000100 /* checksum hash calculated on read */
225 #define B_DONE 0x00000200 /* I/O completed. */
226 #define B_EINTR 0x00000400 /* I/O was interrupted */
227 #define B_NOREUSE 0x00000800 /* Contents not reused once released. */
228 #define B_REUSE 0x00001000 /* Contents reused, second chance. */
229 #define B_INVAL 0x00002000 /* Does not contain valid info. */
230 #define B_BARRIER 0x00004000 /* Write this and all preceding first. */
231 #define B_NOCACHE 0x00008000 /* Do not cache block after use. */
232 #define B_MALLOC 0x00010000 /* malloced b_data */
233 #define B_CLUSTEROK 0x00020000 /* Pagein op, so swap() can count it. */
234 #define B_INVALONERR 0x00040000 /* Invalidate on write error. */
235 #define B_00080000 0x00080000 /* Available flag. */
236 #define B_00100000 0x00100000 /* Available flag. */
237 #define B_MAXPHYS 0x00200000 /* nitems(b_pages[]) = atop(MAXPHYS). */
238 #define B_RELBUF 0x00400000 /* Release VMIO buffer. */
239 #define B_FS_FLAG1 0x00800000 /* Available flag for FS use. */
240 #define B_NOCOPY 0x01000000 /* Don't copy-on-write this buf. */
241 #define B_INFREECNT 0x02000000 /* buf is counted in numfreebufs */
242 #define B_PAGING 0x04000000 /* volatile paging I/O -- bypass VMIO */
243 #define B_MANAGED 0x08000000 /* Managed by FS. */
244 #define B_RAM 0x10000000 /* Read ahead mark (flag) */
245 #define B_VMIO 0x20000000 /* VMIO flag */
246 #define B_CLUSTER 0x40000000 /* pagein op, so swap() can count it */
247 #define B_REMFREE 0x80000000 /* Delayed bremfree */
249 #define PRINT_BUF_FLAGS "\20\40remfree\37cluster\36vmio\35ram\34managed" \
250 "\33paging\32infreecnt\31nocopy\30b23\27relbuf\26maxphys\25b20" \
251 "\24b19\23invalonerr\22clusterok\21malloc\20nocache\17b14\16inval" \
252 "\15reuse\14noreuse\13eintr\12done\11b8\10delwri" \
253 "\7validsuspwrt\6cache\5deferred\4direct\3async\2needcommit\1age"
256 * These flags are kept in b_xflags.
258 * BX_FSPRIV reserves a set of eight flags that may be used by individual
259 * filesystems for their own purpose. Their specific definitions are
260 * found in the header files for each filesystem that uses them.
262 #define BX_VNDIRTY 0x00000001 /* On vnode dirty list */
263 #define BX_VNCLEAN 0x00000002 /* On vnode clean list */
264 #define BX_CVTENXIO 0x00000004 /* Convert errors to ENXIO */
265 #define BX_BKGRDWRITE 0x00000010 /* Do writes in background */
266 #define BX_BKGRDMARKER 0x00000020 /* Mark buffer for splay tree */
267 #define BX_ALTDATA 0x00000040 /* Holds extended data */
268 #define BX_FSPRIV 0x00FF0000 /* Filesystem-specific flags mask */
270 #define PRINT_BUF_XFLAGS "\20\7altdata\6bkgrdmarker\5bkgrdwrite\3cvtenxio" \
273 #define NOOFFSET (-1LL) /* No buffer offset calculated yet */
276 * These flags are kept in b_vflags.
278 #define BV_SCANNED 0x00000001 /* VOP_FSYNC funcs mark written bufs */
279 #define BV_BKGRDINPROG 0x00000002 /* Background write in progress */
280 #define BV_BKGRDWAIT 0x00000004 /* Background write waiting */
281 #define BV_BKGRDERR 0x00000008 /* Error from background write */
283 #define PRINT_BUF_VFLAGS "\20\4bkgrderr\3bkgrdwait\2bkgrdinprog\1scanned"
288 #define NSWBUF_MIN 16
294 extern const char *buf_wmesg; /* Default buffer lock message */
295 #define BUF_WMESG "bufwait"
296 #include <sys/proc.h> /* XXX for curthread */
297 #include <sys/mutex.h>
302 #define BUF_LOCKINIT(bp) \
303 lockinit(&(bp)->b_lock, PRIBIO + 4, buf_wmesg, 0, LK_NEW)
306 * Get a lock sleeping non-interruptably until it becomes available.
308 #define BUF_LOCK(bp, locktype, interlock) \
309 _lockmgr_args_rw(&(bp)->b_lock, (locktype), (interlock), \
310 LK_WMESG_DEFAULT, LK_PRIO_DEFAULT, LK_TIMO_DEFAULT, \
311 LOCK_FILE, LOCK_LINE)
314 * Get a lock sleeping with specified interruptably and timeout.
316 #define BUF_TIMELOCK(bp, locktype, interlock, wmesg, catch, timo) \
317 _lockmgr_args_rw(&(bp)->b_lock, (locktype) | LK_TIMELOCK, \
318 (interlock), (wmesg), (PRIBIO + 4) | (catch), (timo), \
319 LOCK_FILE, LOCK_LINE)
322 * Release a lock. Only the acquiring process may free the lock unless
323 * it has been handed off to biodone.
325 #define BUF_UNLOCK(bp) do { \
326 KASSERT(((bp)->b_flags & B_REMFREE) == 0, \
327 ("BUF_UNLOCK %p while B_REMFREE is still set.", (bp))); \
329 BUF_UNLOCK_RAW((bp)); \
331 #define BUF_UNLOCK_RAW(bp) do { \
332 (void)_lockmgr_args(&(bp)->b_lock, LK_RELEASE, NULL, \
333 LK_WMESG_DEFAULT, LK_PRIO_DEFAULT, LK_TIMO_DEFAULT, \
334 LOCK_FILE, LOCK_LINE); \
338 * Check if a buffer lock is recursed.
340 #define BUF_LOCKRECURSED(bp) \
341 lockmgr_recursed(&(bp)->b_lock)
344 * Check if a buffer lock is currently held.
346 #define BUF_ISLOCKED(bp) \
347 lockstatus(&(bp)->b_lock)
349 * Free a buffer lock.
351 #define BUF_LOCKFREE(bp) \
352 lockdestroy(&(bp)->b_lock)
355 * Print informations on a buffer lock.
357 #define BUF_LOCKPRINTINFO(bp) \
358 lockmgr_printinfo(&(bp)->b_lock)
361 * Buffer lock assertions.
363 #if defined(INVARIANTS) && defined(INVARIANT_SUPPORT)
364 #define BUF_ASSERT_LOCKED(bp) \
365 _lockmgr_assert(&(bp)->b_lock, KA_LOCKED, LOCK_FILE, LOCK_LINE)
366 #define BUF_ASSERT_SLOCKED(bp) \
367 _lockmgr_assert(&(bp)->b_lock, KA_SLOCKED, LOCK_FILE, LOCK_LINE)
368 #define BUF_ASSERT_XLOCKED(bp) \
369 _lockmgr_assert(&(bp)->b_lock, KA_XLOCKED, LOCK_FILE, LOCK_LINE)
370 #define BUF_ASSERT_UNLOCKED(bp) \
371 _lockmgr_assert(&(bp)->b_lock, KA_UNLOCKED, LOCK_FILE, LOCK_LINE)
373 #define BUF_ASSERT_LOCKED(bp)
374 #define BUF_ASSERT_SLOCKED(bp)
375 #define BUF_ASSERT_XLOCKED(bp)
376 #define BUF_ASSERT_UNLOCKED(bp)
379 #ifdef _SYS_PROC_H_ /* Avoid #include <sys/proc.h> pollution */
381 * When initiating asynchronous I/O, change ownership of the lock to the
382 * kernel. Once done, the lock may legally released by biodone. The
383 * original owning process can no longer acquire it recursively, but must
384 * wait until the I/O is completed and the lock has been freed by biodone.
386 #define BUF_KERNPROC(bp) \
387 _lockmgr_disown(&(bp)->b_lock, LOCK_FILE, LOCK_LINE)
392 struct buf_queue_head {
393 TAILQ_HEAD(buf_queue, buf) queue;
395 struct buf *insert_point;
396 struct buf *switch_point;
400 * This structure describes a clustered I/O.
402 struct cluster_save {
403 long bs_bcount; /* Saved b_bcount. */
404 long bs_bufsize; /* Saved b_bufsize. */
405 int bs_nchildren; /* Number of associated buffers. */
406 struct buf **bs_children; /* List of associated buffers. */
412 bwrite(struct buf *bp)
415 KASSERT(bp->b_bufobj != NULL, ("bwrite: no bufobj bp=%p", bp));
416 KASSERT(bp->b_bufobj->bo_ops != NULL, ("bwrite: no bo_ops bp=%p", bp));
417 KASSERT(bp->b_bufobj->bo_ops->bop_write != NULL,
418 ("bwrite: no bop_write bp=%p", bp));
419 return (BO_WRITE(bp->b_bufobj, bp));
423 bstrategy(struct buf *bp)
426 KASSERT(bp->b_bufobj != NULL, ("bstrategy: no bufobj bp=%p", bp));
427 KASSERT(bp->b_bufobj->bo_ops != NULL,
428 ("bstrategy: no bo_ops bp=%p", bp));
429 KASSERT(bp->b_bufobj->bo_ops->bop_strategy != NULL,
430 ("bstrategy: no bop_strategy bp=%p", bp));
431 BO_STRATEGY(bp->b_bufobj, bp);
435 buf_start(struct buf *bp)
438 (*bioops.io_start)(bp);
442 buf_complete(struct buf *bp)
444 if (bioops.io_complete)
445 (*bioops.io_complete)(bp);
449 buf_deallocate(struct buf *bp)
451 if (bioops.io_deallocate)
452 (*bioops.io_deallocate)(bp);
456 buf_countdeps(struct buf *bp, int i)
458 if (bioops.io_countdeps)
459 return ((*bioops.io_countdeps)(bp, i));
465 buf_track(struct buf *bp __unused, const char *location __unused)
468 #if defined(FULL_BUF_TRACKING)
469 bp->b_io_tracking[BUF_TRACKING_ENTRY(bp->b_io_tcnt++)] = location;
470 #elif defined(BUF_TRACKING)
471 bp->b_io_tracking = location;
478 * Zero out the buffer's data area.
480 #define clrbuf(bp) { \
481 bzero((bp)->b_data, (u_int)(bp)->b_bcount); \
486 * Flags for getblk's last parameter.
488 #define GB_LOCK_NOWAIT 0x0001 /* Fail if we block on a buf lock. */
489 #define GB_NOCREAT 0x0002 /* Don't create a buf if not found. */
490 #define GB_NOWAIT_BD 0x0004 /* Do not wait for bufdaemon. */
491 #define GB_UNMAPPED 0x0008 /* Do not mmap buffer pages. */
492 #define GB_KVAALLOC 0x0010 /* But allocate KVA. */
493 #define GB_CKHASH 0x0020 /* If reading, calc checksum hash */
494 #define GB_NOSPARSE 0x0040 /* Do not instantiate holes */
495 #define GB_CVTENXIO 0x0080 /* Convert errors to ENXIO */
498 extern int nbuf; /* The number of buffer headers */
499 extern u_long maxswzone; /* Max KVA for swap structures */
500 extern u_long maxbcache; /* Max KVA for buffer cache */
501 extern int maxbcachebuf; /* Max buffer cache block size */
502 extern long runningbufspace;
503 extern long hibufspace;
504 extern int dirtybufthresh;
505 extern int bdwriteskip;
506 extern int dirtybufferflushes;
507 extern int altbufferflushes;
508 extern int nswbuf; /* Number of swap I/O buffer headers. */
509 extern caddr_t unmapped_buf; /* Data address for unmapped buffers. */
512 buf_mapped(struct buf *bp)
515 return (bp->b_data != unmapped_buf);
518 void runningbufwakeup(struct buf *);
519 void waitrunningbufspace(void);
520 caddr_t kern_vfs_bio_buffer_alloc(caddr_t v, long physmem_est);
522 void bufshutdown(int);
523 void bdata2bio(struct buf *bp, struct bio *bip);
524 void bwillwrite(void);
525 int buf_dirty_count_severe(void);
526 void bremfree(struct buf *);
527 void bremfreef(struct buf *); /* XXX Force bremfree, only for nfs. */
528 #define bread(vp, blkno, size, cred, bpp) \
529 breadn_flags(vp, blkno, blkno, size, NULL, NULL, 0, cred, 0, \
531 #define bread_gb(vp, blkno, size, cred, gbflags, bpp) \
532 breadn_flags(vp, blkno, blkno, size, NULL, NULL, 0, cred, \
534 #define breadn(vp, blkno, size, rablkno, rabsize, cnt, cred, bpp) \
535 breadn_flags(vp, blkno, blkno, size, rablkno, rabsize, cnt, cred, \
537 int breadn_flags(struct vnode *, daddr_t, daddr_t, int, daddr_t *, int *,
538 int, struct ucred *, int, void (*)(struct buf *), struct buf **);
539 void bdwrite(struct buf *);
540 void bawrite(struct buf *);
541 void babarrierwrite(struct buf *);
542 int bbarrierwrite(struct buf *);
543 void bdirty(struct buf *);
544 void bundirty(struct buf *);
545 void bufstrategy(struct bufobj *, struct buf *);
546 void brelse(struct buf *);
547 void bqrelse(struct buf *);
548 int vfs_bio_awrite(struct buf *);
549 void vfs_busy_pages_acquire(struct buf *bp);
550 void vfs_busy_pages_release(struct buf *bp);
551 struct buf *incore(struct bufobj *, daddr_t);
552 bool inmem(struct vnode *, daddr_t);
553 struct buf *gbincore(struct bufobj *, daddr_t);
554 struct buf *gbincore_unlocked(struct bufobj *, daddr_t);
555 struct buf *getblk(struct vnode *, daddr_t, int, int, int, int);
556 int getblkx(struct vnode *vp, daddr_t blkno, daddr_t dblkno, int size,
557 int slpflag, int slptimeo, int flags, struct buf **bpp);
558 struct buf *geteblk(int, int);
559 int bufwait(struct buf *);
560 int bufwrite(struct buf *);
561 void bufdone(struct buf *);
562 void bd_speedup(void);
564 extern uma_zone_t pbuf_zone;
565 uma_zone_t pbuf_zsecond_create(const char *name, int max);
567 int cluster_read(struct vnode *, u_quad_t, daddr_t, long,
568 struct ucred *, long, int, int, struct buf **);
569 int cluster_wbuild(struct vnode *, long, daddr_t, int, int);
570 void cluster_write(struct vnode *, struct buf *, u_quad_t, int, int);
571 void vfs_bio_brelse(struct buf *bp, int ioflags);
572 void vfs_bio_bzero_buf(struct buf *bp, int base, int size);
573 void vfs_bio_clrbuf(struct buf *);
574 void vfs_bio_set_flags(struct buf *bp, int ioflags);
575 void vfs_bio_set_valid(struct buf *, int base, int size);
576 void vfs_busy_pages(struct buf *, int clear_modify);
577 void vfs_unbusy_pages(struct buf *);
578 int vmapbuf(struct buf *, void *, size_t, int);
579 void vunmapbuf(struct buf *);
580 void brelvp(struct buf *);
581 void bgetvp(struct vnode *, struct buf *);
582 void pbgetbo(struct bufobj *bo, struct buf *bp);
583 void pbgetvp(struct vnode *, struct buf *);
584 void pbrelbo(struct buf *);
585 void pbrelvp(struct buf *);
586 int allocbuf(struct buf *bp, int size);
587 void reassignbuf(struct buf *);
588 void bwait(struct buf *, u_char, const char *);
589 void bdone(struct buf *);
591 typedef daddr_t (vbg_get_lblkno_t)(struct vnode *, vm_ooffset_t);
592 typedef int (vbg_get_blksize_t)(struct vnode *, daddr_t);
593 int vfs_bio_getpages(struct vnode *vp, struct vm_page **ma, int count,
594 int *rbehind, int *rahead, vbg_get_lblkno_t get_lblkno,
595 vbg_get_blksize_t get_blksize);
599 #endif /* !_SYS_BUF_H_ */