/* * Copyright (c) 1982, 1986, 1989, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * * 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, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)buf.h 8.9 (Berkeley) 3/30/95 * $FreeBSD: src/sys/sys/buf.h,v 1.88.2.10 2003/01/25 19:02:23 dillon Exp $ * $DragonFly: src/sys/sys/buf.h,v 1.54 2008/08/29 20:08:37 dillon Exp $ */ #ifndef _SYS_BUF_H_ #define _SYS_BUF_H_ #if defined(_KERNEL) || defined(_KERNEL_STRUCTURES) #ifndef _SYS_QUEUE_H_ #include <sys/queue.h> #endif #ifndef _SYS_LOCK_H_ #include <sys/lock.h> #endif #ifndef _SYS_DEVICE_H_ #include <sys/device.h> #endif #ifndef _SYS_XIO_H_ #include <sys/xio.h> #endif #ifndef _SYS_TREE_H_ #include <sys/tree.h> #endif #ifndef _SYS_BIO_H_ #include <sys/bio.h> #endif #ifndef _SYS_SPINLOCK_H_ #include <sys/spinlock.h> #endif struct buf; struct bio; struct mount; struct vnode; struct xio; #define NBUF_BIO 6 struct buf_rb_tree; struct buf_rb_hash; RB_PROTOTYPE2(buf_rb_tree, buf, b_rbnode, rb_buf_compare, off_t); RB_PROTOTYPE2(buf_rb_hash, buf, b_rbhash, rb_buf_compare, off_t); /* * To avoid including <ufs/ffs/softdep.h> */ LIST_HEAD(workhead, worklist); #endif typedef enum buf_cmd { BUF_CMD_DONE = 0, BUF_CMD_READ, BUF_CMD_WRITE, BUF_CMD_FREEBLKS, BUF_CMD_FORMAT, BUF_CMD_FLUSH, BUF_CMD_SEEK, } buf_cmd_t; #if defined(_KERNEL) || defined(_KERNEL_STRUCTURES) /* * The buffer header describes an I/O operation in the kernel. * * NOTES: * b_bufsize represents the filesystem block size (for this particular * block) and/or the allocation size or original request size. This * field is NOT USED by lower device layers. VNode and device * strategy routines WILL NEVER ACCESS THIS FIELD. * * b_bcount represents the I/O request size. Unless B_NOBCLIP is set, * the device chain is allowed to clip b_bcount to accomodate the device * EOF. Note that this is different from the byte oriented file EOF. * If B_NOBCLIP is set, the device chain is required to generate an * error if it would otherwise have to clip the request. Buffers * obtained via getblk() automatically set B_NOBCLIP. It is important * to note that EOF clipping via b_bcount is different from EOF clipping * via returning a b_actual < b_bcount. B_NOBCLIP only effects block * oriented EOF clipping (b_bcount modifications). * * b_actual represents the number of bytes of I/O that actually occured, * whether an error occured or not. b_actual must be initialized to 0 * prior to initiating I/O as the device drivers will assume it to * start at 0. * * b_dirtyoff, b_dirtyend. Buffers support piecemeal, unaligned * ranges of dirty data that need to be written to backing store. * The range is typically clipped at b_bcount (not b_bufsize). * * b_bio1 and b_bio2 represent the two primary I/O layers. Additional * I/O layers are allocated out of the object cache and may also exist. * * b_bio1 is the logical layer and contains offset or block number * data for the primary vnode, b_vp. I/O operations are almost * universally initiated from the logical layer, so you will often * see things like: vn_strategy(bp->b_vp, &bp->b_bio1). * * b_bio2 is the first physical layer (typically the slice-relative * layer) and contains the translated offset or block number for * the block device underlying a filesystem. Filesystems such as UFS * will maintain cached translations and you may see them initiate * a 'physical' I/O using vn_strategy(devvp, &bp->b_bio2). BUT, * remember that the layering is relative to bp->b_vp, so the * device-relative block numbers for buffer cache operations that occur * directly on a block device will be in the first BIO layer. * * b_ops - initialized if a buffer has a bio_ops * * NOTE!!! Only the BIO subsystem accesses b_bio1 and b_bio2 directly. * ALL STRATEGY LAYERS FOR BOTH VNODES AND DEVICES ONLY ACCESS THE BIO * PASSED TO THEM, AND WILL PUSH ANOTHER BIO LAYER IF FORWARDING THE * I/O DEEPER. In particular, a vn_strategy() or dev_dstrategy() * call should not ever access buf->b_vp as this vnode may be totally * unrelated to the vnode/device whos strategy routine was called. */ struct buf { RB_ENTRY(buf) b_rbnode; /* RB node in vnode clean/dirty tree */ RB_ENTRY(buf) b_rbhash; /* RB node in vnode hash tree */ TAILQ_ENTRY(buf) b_freelist; /* Free list position if not active. */ struct buf *b_cluster_next; /* Next buffer (cluster code) */ struct vnode *b_vp; /* (vp, loffset) index */ struct bio b_bio_array[NBUF_BIO]; /* BIO translation layers */ u_int32_t b_flags; /* B_* flags. */ unsigned int b_qindex; /* buffer queue index */ unsigned int b_qcpu; /* buffer queue cpu */ unsigned char b_act_count; /* similar to vm_page act_count */ unsigned char b_swindex; cpumask_t b_cpumask; /* KVABIO API */ struct lock b_lock; /* Buffer lock */ buf_cmd_t b_cmd; /* I/O command */ int b_bufsize; /* Allocated buffer size. */ int b_runningbufspace; /* when I/O is running, pipelining */ int b_bcount; /* Valid bytes in buffer. */ int b_resid; /* Remaining I/O */ int b_error; /* Error return */ caddr_t b_data; /* Memory, superblocks, indirect etc. */ caddr_t b_kvabase; /* base kva for buffer */ int b_kvasize; /* size of kva for buffer */ int b_dirtyoff; /* Offset in buffer of dirty region. */ int b_dirtyend; /* Offset of end of dirty region. */ int b_refs; /* FINDBLK_REF/bqhold()/bqdrop() */ struct xio b_xio; /* data buffer page list management */ struct bio_ops *b_ops; /* bio_ops used w/ b_dep */ union { struct workhead b_dep; /* List of filesystem dependencies. */ void *b_priv; /* Filesystem private data */ }; }; /* * XXX temporary */ #define b_bio1 b_bio_array[0] /* logical layer */ #define b_bio2 b_bio_array[1] /* (typically) the disk layer */ #define b_loffset b_bio1.bio_offset /* * Flags passed to getblk() * * GETBLK_PCATCH - Allow signals to be caught. getblk() is allowed to return * NULL if this flag is passed. * * GETBLK_BHEAVY - This is a heavy weight buffer, meaning that resolving * writes can require additional buffers. * * GETBLK_SZMATCH- blksize must match pre-existing b_bcount. getblk() can * return NULL. * * GETBLK_NOWAIT - Do not use a blocking lock. getblk() can return NULL. */ #define GETBLK_PCATCH 0x0001 /* catch signals */ #define GETBLK_BHEAVY 0x0002 /* heavy weight buffer */ #define GETBLK_SZMATCH 0x0004 /* pre-existing buffer must match */ #define GETBLK_NOWAIT 0x0008 /* non-blocking */ #define GETBLK_KVABIO 0x0010 /* request a B_KVABIO buffer */ #define FINDBLK_TEST 0x0020 /* test only, do not lock */ #define FINDBLK_NBLOCK 0x0040 /* use non-blocking lock, can return NULL */ #define FINDBLK_REF 0x0080 /* ref the buf to prevent reuse */ #define FINDBLK_KVABIO 0x0100 /* (if locking only) request B_KVABIO buffer */ /* * These flags are kept in b_flags. * * Notes: * * B_PAGING Indicates that bp is being used by the paging system or * some paging system and that the bp is not linked into * the b_vp's clean/dirty linked lists or ref counts. * Buffer vp reassignments are illegal in this case. * * B_CACHE This may only be set if the buffer is entirely valid. * The situation where B_DELWRI is set and B_CACHE is * clear MUST be committed to disk by getblk() so * B_DELWRI can also be cleared. See the comments for * getblk() in kern/vfs_bio.c. If B_CACHE is clear, * the caller is expected to clear B_ERROR|B_INVAL, * set BUF_CMD_READ, and initiate an I/O. * * The 'entire buffer' is defined to be the range from * 0 through b_bcount. * * B_CLUSTEROK This flag is typically set for B_DELWRI buffers * by filesystems that allow clustering when the buffer * is fully dirty and indicates that it may be clustered * with other adjacent dirty buffers. Note the clustering * may not be used with the stage 1 data write under NFS * but may be used for the commit rpc portion. * * B_VMIO Indicates that the buffer is tied into an VM object. * The buffer's data is always PAGE_SIZE aligned even * if b_bufsize and b_bcount are not. ( b_bufsize is * always at least DEV_BSIZE aligned, though ). * * B_DIRECT Hint that we should attempt to completely free * the pages underlying the buffer. B_DIRECT is * sticky until the buffer is released and typically * only has an effect when B_RELBUF is also set. * * B_LOCKED The buffer will be released to the locked queue * regardless of its current state. Note that * if B_DELWRI is set, no I/O occurs until the caller * acquires the buffer, clears B_LOCKED, then releases * it again. * * B_AGE When allocating a new buffer any buffer encountered * with B_AGE set will be reallocated more quickly then * buffers encountered without it set. B_AGE is set * as part of the loop so idle buffers should eventually * wind up with B_AGE set. B_AGE explicitly does NOT * cause the buffer to be instantly reallocated for * other purposes. * * Standard buffer flushing routines leave B_AGE intact * through the DIRTY queue and into the CLEAN queue. * Setting B_AGE on a dirty buffer will not cause it * to be flushed more quickly but will cause it to be * reallocated more quickly after having been flushed. * * B_NOCACHE Request that the buffer and backing store be * destroyed on completion. If B_DELWRI is set and the * write fails, the buffer remains intact. * * B_NOTMETA May be set on block device buffers representing * file data (i.e. which aren't really meta-data), * which will cause the buffer cache to set PG_NOTMETA * in the VM pages when releasing them and the * swapcache to not try to cache them. * * B_MARKER Special marker buf, always skip. * * B_KVABIO Owner of buffer (but not necessarily the underlying * vnode or device) supports the KVABIO API. The owner * of the buffer will only operate on the buffer's * b_data via the API. Locked buffers only. This * flag is cleared on brelse/bqrelse * * WARNING! bp->b_data is not necessarily synchronized to the current cpu * when B_KVABIO operations is specified. Callers using bp->b_data * who specify B_KVABIO operation must call bkvasync() if they use * bp->b_data directly, or whenever they pass a buffer between cpus * (between threads, e.g. from helper threads) if the target thread * intends to access bp->b_data. */ #define B_AGE 0x00000001 /* Reuse more quickly */ #define B_NEEDCOMMIT 0x00000002 /* Append-write in progress. */ #define B_NOTMETA 0x00000004 /* This really isn't metadata */ #define B_DIRECT 0x00000008 /* direct I/O flag (pls free vmio) */ #define B_DEFERRED 0x00000010 /* vfs-controlled deferment */ #define B_CACHE 0x00000020 /* Bread found us in the cache. */ #define B_HASHED 0x00000040 /* Indexed via v_rbhash_tree */ #define B_DELWRI 0x00000080 /* Delay I/O until buffer reused. */ #define B_BNOCLIP 0x00000100 /* EOF clipping b_bcount not allowed */ #define B_HASBOGUS 0x00000200 /* Contains bogus pages */ #define B_EINTR 0x00000400 /* I/O was interrupted */ #define B_ERROR 0x00000800 /* I/O error occurred. */ #define B_IOISSUED 0x00001000 /* Flag when I/O issued (vfs can clr) */ #define B_INVAL 0x00002000 /* Does not contain valid info. */ #define B_LOCKED 0x00004000 /* Locked in core (not reusable). */ #define B_NOCACHE 0x00008000 /* Destroy buffer AND backing store */ #define B_KVABIO 0x00010000 /* Lockholder uses the KVABIO API */ #define B_CLUSTEROK 0x00020000 /* Pagein op, so swap() can count it. */ #define B_MARKER 0x00040000 /* Special marker buf in queue */ #define B_RAW 0x00080000 /* Set by physio for raw transfers. */ #define B_HEAVY 0x00100000 /* Heavy-weight buffer */ #define B_DIRTY 0x00200000 /* Needs writing later. */ #define B_RELBUF 0x00400000 /* Release VMIO buffer. */ #define B_FAILONDIS 0x00800000 /* Fail on disconnect */ #define B_VNCLEAN 0x01000000 /* On vnode clean list */ #define B_VNDIRTY 0x02000000 /* On vnode dirty list */ #define B_PAGING 0x04000000 /* volatile paging I/O -- bypass VMIO */ #define B_TTC 0x08000000 /* Try to recycle pages to PQ_CACHE */ #define B_RAM 0x10000000 /* Read ahead mark (flag) */ #define B_VMIO 0x20000000 /* VMIO flag */ #define B_CLUSTER 0x40000000 /* pagein op, so swap() can count it */ #define B_VFSFLAG1 0x80000000 /* VFSs can set this flag */ #define PRINT_BUF_FLAGS "\20" \ "\40unused31\37cluster\36vmio\35ram\34ordered" \ "\33paging\32vndirty\31vnclean\30unused23\27relbuf\26dirty" \ "\25unused20\24raw\23unused18\22clusterok\21malloc\20nocache" \ "\17locked\16inval\15unused12\14error\13eintr\12unused9\11bnoclip" \ "\10delwri\7hashed\6cache\5deferred\4direct\3unused2\2needcommit\1age" #define NOOFFSET (-1LL) /* No buffer offset calculated yet */ #ifdef _KERNEL /* * Buffer locking. See sys/buf2.h for inline functions. */ extern char *buf_wmesg; /* Default buffer lock message */ #define BUF_WMESG "bufwait" #endif /* _KERNEL */ struct bio_queue_head { TAILQ_HEAD(bio_queue, bio) queue; off_t off_unused; int reorder; struct bio *transition; struct bio *bio_unused; }; /* * This structure describes a clustered I/O. */ struct cluster_save { int bs_nchildren; /* Number of associated buffers. */ struct buf **bs_children; /* List of associated buffers. */ }; /* * Zero out the buffer's data area. */ #define clrbuf(bp) do { \ bkvasync((bp)); \ bzero((bp)->b_data, (u_int)(bp)->b_bcount); \ (bp)->b_resid = 0; \ } while(0) /* * Flags to low-level bitmap allocation routines (balloc). * * Note: sequential_heuristic() in kern/vfs_vnops.c limits the count * to 127. */ #define B_SEQMASK 0x7F000000 /* Sequential heuristic mask. */ #define B_SEQSHIFT 24 /* Sequential heuristic shift. */ #define B_SEQMAX 0x7F #define B_CLRBUF 0x01 /* Cleared invalid areas of buffer. */ #define B_SYNC 0x02 /* Do all allocations synchronously. */ /* * Split nswbuf_kva by N, allowing each block device or mounted filesystem * to use up to (nswbuf_kva / N) pbufs. */ #define NSWBUF_SPLIT 10 /* split nswbuf_kva by N */ #ifdef _KERNEL extern long nbuf; /* The number of buffer headers */ extern long maxswzone; /* Max KVA for swap structures */ extern long maxbcache; /* Max KVA for buffer cache */ extern long hidirtybufspace; extern int buf_maxio; /* nominal maximum I/O for buffer */ extern struct buf *buf; /* The buffer headers. */ extern char *buffers; /* The buffer contents. */ extern int bufpages; /* Number of memory pages in the buffer pool. */ extern struct buf *swbuf_mem; /* Swap I/O buffer headers. */ extern struct buf *swbuf_kva; /* Swap I/O buffer headers. */ extern struct buf *swbuf_raw; /* Swap I/O buffer headers. */ extern long nswbuf_mem; /* Number of swap I/O buffer headers. */ extern long nswbuf_kva; /* Number of swap I/O buffer headers. */ extern long nswbuf_raw; /* Number of swap I/O buffer headers. */ extern int bioq_reorder_burst_interval; extern int bioq_reorder_burst_bytes; extern int bioq_reorder_minor_interval; extern int bioq_reorder_minor_bytes; struct uio; struct devstat; long bd_heatup (void); void bd_wait (long count); void waitrunningbufspace(void); int buf_dirty_count_severe (void); int buf_runningbufspace_severe (void); void initbufbio(struct buf *); void uninitbufbio(struct buf *); void reinitbufbio(struct buf *); void clearbiocache(struct bio *); void bremfree (struct buf *); int breadx (struct vnode *, off_t, int, int, struct buf **); int breadnx (struct vnode *, off_t, int, int, off_t *, int *, int, struct buf **); void breadcb(struct vnode *, off_t, int, int, void (*)(struct bio *), void *); int bwrite (struct buf *); void bdwrite (struct buf *); void buwrite (struct buf *); void bawrite (struct buf *); void bdirty (struct buf *); void bheavy (struct buf *); void bundirty (struct buf *); void brelse (struct buf *); void bqrelse (struct buf *); int cluster_awrite (struct buf *); void bkvareset(struct buf *bp); void bkvasync(struct buf *bp); void bkvasync_all(struct buf *bp); struct buf *getpbuf (int *); struct buf *getpbuf_mem (int *); struct buf *getpbuf_kva (int *); int inmem (struct vnode *, off_t); struct buf *findblk (struct vnode *, off_t, int); struct buf *getblk (struct vnode *, off_t, int, int, int); struct buf *getcacheblk (struct vnode *, off_t, int, int); struct buf *getnewbuf(int, int, int, int); void bqhold(struct buf *bp); void bqdrop(struct buf *bp); void regetblk(struct buf *bp); struct bio *push_bio(struct bio *); struct bio *pop_bio(struct bio *); int biowait (struct bio *, const char *); int biowait_timeout (struct bio *, const char *, int); void bpdone (struct buf *, int); void biodone (struct bio *); void biodone_sync (struct bio *); void pbuf_adjcount(int *pfreecnt, int n); void cluster_append(struct bio *, struct buf *); int cluster_readx (struct vnode *, off_t, off_t, int, int, size_t, size_t, struct buf **); void cluster_readcb (struct vnode *, off_t, off_t, int, int, size_t, size_t, void (*func)(struct bio *), void *arg); void cluster_write (struct buf *, off_t, int, int); int physread (struct dev_read_args *); int physwrite (struct dev_write_args *); void vfs_bio_clrbuf (struct buf *); void vfs_busy_pages (struct vnode *, struct buf *); void vfs_unbusy_pages (struct buf *); void relpbuf (struct buf *, int *); void brelvp (struct buf *); int bgetvp (struct vnode *, struct buf *, int); void bsetrunningbufspace(struct buf *, int); void allocbuf (struct buf *bp, int size); int scan_all_buffers (int (*)(struct buf *, void *), void *); void reassignbuf (struct buf *); struct buf *trypbuf (int *); struct buf *trypbuf_kva (int *); void bio_ops_sync(struct mount *mp); void nestiobuf_done(struct bio *mbio, int donebytes, int error, struct devstat *stats); void nestiobuf_init(struct bio *mbio); void nestiobuf_add(struct bio *mbio, struct buf *bp, int off, size_t size, struct devstat *stats); void nestiobuf_start(struct bio *mbio); void nestiobuf_error(struct bio *mbio, int error); const char *buf_cmd_name(struct buf *bp); #endif /* _KERNEL */ #endif /* _KERNEL || _KERNEL_STRUCTURES */ #endif /* !_SYS_BUF_H_ */
