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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 1.4 2003/06/26 05:55:19 dillon Exp $
46 #include <sys/queue.h>
54 * To avoid including <ufs/ffs/softdep.h>
56 LIST_HEAD(workhead, worklist);
58 * These are currently used only by the soft dependency code, hence
59 * are stored once in a global variable. If other subsystems wanted
60 * to use these hooks, a pointer to a set of bio_ops could be added
63 extern struct bio_ops {
64 void (*io_start) __P((struct buf *));
65 void (*io_complete) __P((struct buf *));
66 void (*io_deallocate) __P((struct buf *));
67 int (*io_fsync) __P((struct vnode *));
68 int (*io_sync) __P((struct mount *));
69 void (*io_movedeps) __P((struct buf *, struct buf *));
70 int (*io_countdeps) __P((struct buf *, int));
75 void (*ic_prev_iodone) __P((struct buf *));
76 void *ic_prev_iodone_chain;
84 * The buffer header describes an I/O operation in the kernel.
87 * b_bufsize, b_bcount. b_bufsize is the allocation size of the
88 * buffer, either DEV_BSIZE or PAGE_SIZE aligned. b_bcount is the
89 * originally requested buffer size and can serve as a bounds check
90 * against EOF. For most, but not all uses, b_bcount == b_bufsize.
92 * b_dirtyoff, b_dirtyend. Buffers support piecemeal, unaligned
93 * ranges of dirty data that need to be written to backing store.
94 * The range is typically clipped at b_bcount ( not b_bufsize ).
96 * b_resid. Number of bytes remaining in I/O. After an I/O operation
97 * completes, b_resid is usually 0 indicating 100% success.
100 LIST_ENTRY(buf) b_hash; /* Hash chain. */
101 TAILQ_ENTRY(buf) b_vnbufs; /* Buffer's associated vnode. */
102 TAILQ_ENTRY(buf) b_freelist; /* Free list position if not active. */
103 TAILQ_ENTRY(buf) b_act; /* Device driver queue when active. *new* */
104 long b_flags; /* B_* flags. */
105 unsigned short b_qindex; /* buffer queue index */
106 unsigned char b_xflags; /* extra flags */
107 struct lock b_lock; /* Buffer lock */
108 int b_error; /* Errno value. */
109 long b_bufsize; /* Allocated buffer size. */
110 long b_runningbufspace; /* when I/O is running, pipelining */
111 long b_bcount; /* Valid bytes in buffer. */
112 long b_resid; /* Remaining I/O. */
113 dev_t b_dev; /* Device associated with buffer. */
114 caddr_t b_data; /* Memory, superblocks, indirect etc. */
115 caddr_t b_kvabase; /* base kva for buffer */
116 int b_kvasize; /* size of kva for buffer */
117 daddr_t b_lblkno; /* Logical block number. */
118 daddr_t b_blkno; /* Underlying physical block number. */
119 off_t b_offset; /* Offset into file */
120 /* Function to call upon completion. */
121 void (*b_iodone) __P((struct buf *));
122 /* For nested b_iodone's. */
123 struct iodone_chain *b_iodone_chain;
124 struct vnode *b_vp; /* Device vnode. */
125 int b_dirtyoff; /* Offset in buffer of dirty region. */
126 int b_dirtyend; /* Offset of end of dirty region. */
127 daddr_t b_pblkno; /* physical block number */
128 void *b_saveaddr; /* Original b_addr for physio. */
129 void *b_driver1; /* for private use by the driver */
130 void *b_driver2; /* for private use by the driver */
131 void *b_caller1; /* for private use by the caller */
132 void *b_caller2; /* for private use by the caller */
138 TAILQ_HEAD(cluster_list_head, buf) cluster_head;
139 TAILQ_ENTRY(buf) cluster_entry;
141 struct vm_page *b_pages[btoc(MAXPHYS)];
143 struct workhead b_dep; /* List of filesystem dependencies. */
144 struct chain_info { /* buffer chaining */
150 #define b_spc b_pager.pg_spc
153 * These flags are kept in b_flags.
157 * B_ASYNC VOP calls on bp's are usually async whether or not
158 * B_ASYNC is set, but some subsystems, such as NFS, like
159 * to know what is best for the caller so they can
162 * B_PAGING Indicates that bp is being used by the paging system or
163 * some paging system and that the bp is not linked into
164 * the b_vp's clean/dirty linked lists or ref counts.
165 * Buffer vp reassignments are illegal in this case.
167 * B_CACHE This may only be set if the buffer is entirely valid.
168 * The situation where B_DELWRI is set and B_CACHE is
169 * clear MUST be committed to disk by getblk() so
170 * B_DELWRI can also be cleared. See the comments for
171 * getblk() in kern/vfs_bio.c. If B_CACHE is clear,
172 * the caller is expected to clear B_ERROR|B_INVAL,
173 * set B_READ, and initiate an I/O.
175 * The 'entire buffer' is defined to be the range from
176 * 0 through b_bcount.
178 * B_MALLOC Request that the buffer be allocated from the malloc
179 * pool, DEV_BSIZE aligned instead of PAGE_SIZE aligned.
181 * B_CLUSTEROK This flag is typically set for B_DELWRI buffers
182 * by filesystems that allow clustering when the buffer
183 * is fully dirty and indicates that it may be clustered
184 * with other adjacent dirty buffers. Note the clustering
185 * may not be used with the stage 1 data write under NFS
186 * but may be used for the commit rpc portion.
188 * B_VMIO Indicates that the buffer is tied into an VM object.
189 * The buffer's data is always PAGE_SIZE aligned even
190 * if b_bufsize and b_bcount are not. ( b_bufsize is
191 * always at least DEV_BSIZE aligned, though ).
193 * B_DIRECT Hint that we should attempt to completely free
194 * the pages underlying the buffer. B_DIRECT is
195 * sticky until the buffer is released and typically
196 * only has an effect when B_RELBUF is also set.
198 * B_NOWDRAIN This flag should be set when a device (like VN)
199 * does a turn-around VOP_WRITE from its strategy
200 * routine. This flag prevents bwrite() from blocking
201 * in wdrain, avoiding a deadlock situation.
204 #define B_AGE 0x00000001 /* Move to age queue when I/O done. */
205 #define B_NEEDCOMMIT 0x00000002 /* Append-write in progress. */
206 #define B_ASYNC 0x00000004 /* Start I/O, do not wait. */
207 #define B_DIRECT 0x00000008 /* direct I/O flag (pls free vmio) */
208 #define B_DEFERRED 0x00000010 /* Skipped over for cleaning */
209 #define B_CACHE 0x00000020 /* Bread found us in the cache. */
210 #define B_CALL 0x00000040 /* Call b_iodone from biodone. */
211 #define B_DELWRI 0x00000080 /* Delay I/O until buffer reused. */
212 #define B_FREEBUF 0x00000100 /* Instruct driver: free blocks */
213 #define B_DONE 0x00000200 /* I/O completed. */
214 #define B_EINTR 0x00000400 /* I/O was interrupted */
215 #define B_ERROR 0x00000800 /* I/O error occurred. */
216 #define B_SCANNED 0x00001000 /* VOP_FSYNC funcs mark written bufs */
217 #define B_INVAL 0x00002000 /* Does not contain valid info. */
218 #define B_LOCKED 0x00004000 /* Locked in core (not reusable). */
219 #define B_NOCACHE 0x00008000 /* Do not cache block after use. */
220 #define B_MALLOC 0x00010000 /* malloced b_data */
221 #define B_CLUSTEROK 0x00020000 /* Pagein op, so swap() can count it. */
222 #define B_PHYS 0x00040000 /* I/O to user memory. */
223 #define B_RAW 0x00080000 /* Set by physio for raw transfers. */
224 #define B_READ 0x00100000 /* Read buffer. */
225 #define B_DIRTY 0x00200000 /* Needs writing later. */
226 #define B_RELBUF 0x00400000 /* Release VMIO buffer. */
227 #define B_WANT 0x00800000 /* Used by vm_pager.c */
228 #define B_WRITE 0x00000000 /* Write buffer (pseudo flag). */
229 #define B_WRITEINPROG 0x01000000 /* Write in progress. */
230 #define B_XXX 0x02000000 /* Debugging flag. */
231 #define B_PAGING 0x04000000 /* volatile paging I/O -- bypass VMIO */
232 #define B_ORDERED 0x08000000 /* Must guarantee I/O ordering */
233 #define B_RAM 0x10000000 /* Read ahead mark (flag) */
234 #define B_VMIO 0x20000000 /* VMIO flag */
235 #define B_CLUSTER 0x40000000 /* pagein op, so swap() can count it */
236 #define B_NOWDRAIN 0x80000000 /* Avoid wdrain deadlock */
238 #define PRINT_BUF_FLAGS "\20\40nowdrain\37cluster\36vmio\35ram\34ordered" \
239 "\33paging\32xxx\31writeinprog\30want\27relbuf\26dirty" \
240 "\25read\24raw\23phys\22clusterok\21malloc\20nocache" \
241 "\17locked\16inval\15scanned\14error\13eintr\12done\11freebuf" \
242 "\10delwri\7call\6cache\4direct\3async\2needcommit\1age"
245 * These flags are kept in b_xflags.
247 #define BX_VNDIRTY 0x00000001 /* On vnode dirty list */
248 #define BX_VNCLEAN 0x00000002 /* On vnode clean list */
249 #define BX_BKGRDWRITE 0x00000004 /* Do writes in background */
250 #define BX_BKGRDINPROG 0x00000008 /* Background write in progress */
251 #define BX_BKGRDWAIT 0x00000010 /* Background write waiting */
252 #define BX_AUTOCHAINDONE 0x00000020 /* pager I/O chain auto mode */
254 #define NOOFFSET (-1LL) /* No buffer offset calculated yet */
258 * Buffer locking. See sys/buf2.h for inline functions.
260 struct simplelock buftimelock; /* Interlock on setting prio and timo */
261 extern char *buf_wmesg; /* Default buffer lock message */
262 #define BUF_WMESG "bufwait"
266 struct buf_queue_head {
267 TAILQ_HEAD(buf_queue, buf) queue;
269 struct buf *insert_point;
270 struct buf *switch_point;
274 * This structure describes a clustered I/O. It is stored in the b_saveaddr
275 * field of the buffer on which I/O is done. At I/O completion, cluster
276 * callback uses the structure to parcel I/O's to individual buffers, and
277 * then free's this structure.
279 struct cluster_save {
280 long bs_bcount; /* Saved b_bcount. */
281 long bs_bufsize; /* Saved b_bufsize. */
282 void *bs_saveaddr; /* Saved b_addr. */
283 int bs_nchildren; /* Number of associated buffers. */
284 struct buf **bs_children; /* List of associated buffers. */
288 * Definitions for the buffer free lists.
290 #define BUFFER_QUEUES 6 /* number of free buffer queues */
292 #define QUEUE_NONE 0 /* on no queue */
293 #define QUEUE_LOCKED 1 /* locked buffers */
294 #define QUEUE_CLEAN 2 /* non-B_DELWRI buffers */
295 #define QUEUE_DIRTY 3 /* B_DELWRI buffers */
296 #define QUEUE_EMPTYKVA 4 /* empty buffer headers w/KVA assignment */
297 #define QUEUE_EMPTY 5 /* empty buffer headers */
300 * Zero out the buffer's data area.
302 #define clrbuf(bp) { \
303 bzero((bp)->b_data, (u_int)(bp)->b_bcount); \
308 * Flags to low-level bitmap allocation routines (balloc).
310 * Note: sequential_heuristic() in kern/vfs_vnops.c limits the count
313 #define B_SEQMASK 0x7F000000 /* Sequential heuristic mask. */
314 #define B_SEQSHIFT 24 /* Sequential heuristic shift. */
315 #define B_SEQMAX 0x7F
316 #define B_CLRBUF 0x01 /* Cleared invalid areas of buffer. */
317 #define B_SYNC 0x02 /* Do all allocations synchronously. */
320 extern int nbuf; /* The number of buffer headers */
321 extern int maxswzone; /* Max KVA for swap structures */
322 extern int maxbcache; /* Max KVA for buffer cache */
323 extern int runningbufspace;
324 extern int buf_maxio; /* nominal maximum I/O for buffer */
325 extern struct buf *buf; /* The buffer headers. */
326 extern char *buffers; /* The buffer contents. */
327 extern int bufpages; /* Number of memory pages in the buffer pool. */
328 extern struct buf *swbuf; /* Swap I/O buffer headers. */
329 extern int nswbuf; /* Number of swap I/O buffer headers. */
330 extern TAILQ_HEAD(swqueue, buf) bswlist;
331 extern TAILQ_HEAD(bqueues, buf) bufqueues[BUFFER_QUEUES];
335 caddr_t bufhashinit __P((caddr_t));
336 void bufinit __P((void));
337 void bwillwrite __P((void));
338 int buf_dirty_count_severe __P((void));
339 void bremfree __P((struct buf *));
340 int bread __P((struct vnode *, daddr_t, int, struct buf **));
341 int breadn __P((struct vnode *, daddr_t, int, daddr_t *, int *, int,
343 int bwrite __P((struct buf *));
344 void bdwrite __P((struct buf *));
345 void bawrite __P((struct buf *));
346 void bdirty __P((struct buf *));
347 void bundirty __P((struct buf *));
348 int bowrite __P((struct buf *));
349 void brelse __P((struct buf *));
350 void bqrelse __P((struct buf *));
351 int vfs_bio_awrite __P((struct buf *));
352 struct buf * getpbuf __P((int *));
353 struct buf *incore __P((struct vnode *, daddr_t));
354 struct buf *gbincore __P((struct vnode *, daddr_t));
355 int inmem __P((struct vnode *, daddr_t));
356 struct buf *getblk __P((struct vnode *, daddr_t, int, int, int));
357 struct buf *geteblk __P((int));
358 int biowait __P((struct buf *));
359 void biodone __P((struct buf *));
361 void cluster_callback __P((struct buf *));
362 int cluster_read __P((struct vnode *, u_quad_t, daddr_t, long,
363 long, int, struct buf **));
364 int cluster_wbuild __P((struct vnode *, long, daddr_t, int));
365 void cluster_write __P((struct buf *, u_quad_t, int));
366 int physio __P((dev_t dev, struct uio *uio, int ioflag));
367 #define physread physio
368 #define physwrite physio
369 void vfs_bio_set_validclean __P((struct buf *, int base, int size));
370 void vfs_bio_clrbuf __P((struct buf *));
371 void vfs_busy_pages __P((struct buf *, int clear_modify));
372 void vfs_unbusy_pages __P((struct buf *));
373 void vwakeup __P((struct buf *));
374 int vmapbuf __P((struct buf *));
375 void vunmapbuf __P((struct buf *));
376 void relpbuf __P((struct buf *, int *));
377 void brelvp __P((struct buf *));
378 void bgetvp __P((struct vnode *, struct buf *));
379 void pbgetvp __P((struct vnode *, struct buf *));
380 void pbrelvp __P((struct buf *));
381 int allocbuf __P((struct buf *bp, int size));
382 void reassignbuf __P((struct buf *, struct vnode *));
383 void pbreassignbuf __P((struct buf *, struct vnode *));
384 struct buf *trypbuf __P((int *));
388 #endif /* !_SYS_BUF_H_ */