2 * Copyright (c) 2000-2003 Tor Egge
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * $FreeBSD: src/sys/ufs/ffs/ffs_rawread.c,v 1.3.2.2 2003/05/29 06:15:35 alc Exp $
27 * $DragonFly: src/sys/vfs/ufs/ffs_rawread.c,v 1.28 2008/06/19 23:27:39 dillon Exp $
30 #include <sys/param.h>
31 #include <sys/systm.h>
32 #include <sys/fcntl.h>
36 #include <sys/mount.h>
37 #include <sys/namei.h>
38 #include <sys/vnode.h>
40 #include <sys/filio.h>
41 #include <sys/ttycom.h>
47 #include <machine/limits.h>
49 #include <vm/vm_extern.h>
50 #include <vm/vm_object.h>
51 #include <sys/kernel.h>
52 #include <sys/sysctl.h>
54 static int ffs_rawread_readahead(struct vnode *vp, caddr_t udata, off_t offset,
55 size_t len, struct buf *bp, int *baseticks);
56 static int ffs_rawread_main(struct vnode *vp,
59 static int ffs_rawread_sync(struct vnode *vp);
61 int ffs_rawread(struct vnode *vp, struct uio *uio, int *workdone);
63 void ffs_rawread_setup(void);
65 SYSCTL_DECL(_vfs_ffs);
67 static int ffsrawbufcnt = 4;
68 SYSCTL_INT(_vfs_ffs, OID_AUTO, ffsrawbufcnt, CTLFLAG_RD, &ffsrawbufcnt, 0,
69 "Buffers available for raw reads");
71 static int allowrawread = 1;
72 SYSCTL_INT(_vfs_ffs, OID_AUTO, allowrawread, CTLFLAG_RW, &allowrawread, 0,
73 "Flag to enable raw reads");
75 static int rawreadahead = 1;
76 SYSCTL_INT(_vfs_ffs, OID_AUTO, rawreadahead, CTLFLAG_RW, &rawreadahead, 0,
77 "Flag to enable readahead for long raw reads");
81 ffs_rawread_setup(void)
83 ffsrawbufcnt = (nswbuf > 100 ) ? (nswbuf - (nswbuf >> 4)) : nswbuf - 8;
88 ffs_rawread_sync(struct vnode *vp)
95 * Check for dirty mmap, pending writes and dirty buffers
97 lwkt_gettoken(&vlock, &vp->v_token);
98 if (bio_track_active(&vp->v_track_write) ||
99 !RB_EMPTY(&vp->v_rbdirty_tree) ||
100 (vp->v_flag & VOBJDIRTY) != 0) {
101 if (vn_islocked(vp) != LK_EXCLUSIVE) {
103 /* Upgrade to exclusive lock, this might block */
104 vn_lock(vp, LK_UPGRADE);
108 /* Attempt to msync mmap() regions to clean dirty mmap */
109 if ((vp->v_flag & VOBJDIRTY) != 0) {
110 struct vm_object *obj;
111 if ((obj = vp->v_object) != NULL)
112 vm_object_page_clean(obj, 0, 0, OBJPC_SYNC);
115 /* Wait for pending writes to complete */
116 error = bio_track_wait(&vp->v_track_write, 0, 0);
119 vn_lock(vp, LK_DOWNGRADE);
122 /* Flush dirty buffers */
123 if (!RB_EMPTY(&vp->v_rbdirty_tree)) {
124 if ((error = VOP_FSYNC(vp, MNT_WAIT, 0)) != 0) {
126 vn_lock(vp, LK_DOWNGRADE);
129 if (bio_track_active(&vp->v_track_write) ||
130 !RB_EMPTY(&vp->v_rbdirty_tree))
131 panic("ffs_rawread_sync: dirty bufs");
134 vn_lock(vp, LK_DOWNGRADE);
139 lwkt_reltoken(&vlock);
145 ffs_rawread_readahead(struct vnode *vp, caddr_t udata, off_t loffset,
146 size_t len, struct buf *bp, int *baseticks)
155 bsize = vp->v_mount->mnt_stat.f_iosize;
158 * Make sure it fits into the pbuf
160 iolen = (int)(intptr_t)udata & PAGE_MASK;
161 if (len + iolen > bp->b_kvasize) {
168 * Raw disk address is in bio2, but we wait for it to
171 bp->b_flags &= ~B_ERROR;
172 bp->b_loffset = loffset;
173 bp->b_bio2.bio_offset = NOOFFSET;
174 bp->b_bio1.bio_done = biodone_sync;
175 bp->b_bio1.bio_flags |= BIO_SYNC;
177 blockoff = (loffset % bsize) / DEV_BSIZE;
179 error = VOP_BMAP(vp, bp->b_loffset, &bp->b_bio2.bio_offset,
180 &bforwards, NULL, BUF_CMD_READ);
183 dp = VTOI(vp)->i_devvp;
184 if (bp->b_bio2.bio_offset == NOOFFSET) {
186 * Fill holes with NULs to preserve semantics
188 if (len + blockoff * DEV_BSIZE > bsize)
189 len = bsize - blockoff * DEV_BSIZE;
191 if (vmapbuf(bp, udata, len) < 0)
194 if (ticks - *baseticks >= hogticks) {
198 bzero(bp->b_data, bp->b_bcount);
200 /* Mark operation completed (similar to bufdone()) */
206 if (len + blockoff * DEV_BSIZE > bforwards)
207 len = bforwards - blockoff * DEV_BSIZE;
208 bp->b_bio2.bio_offset += blockoff * DEV_BSIZE;
210 if (vmapbuf(bp, udata, len) < 0)
214 * Access the block device layer using the device vnode (dp) and
215 * the translated block number (bio2) instead of the logical block
218 * Even though we are bypassing the vnode layer, we still
219 * want the vnode state to indicate that an I/O on its behalf
222 bp->b_cmd = BUF_CMD_READ;
223 bio_start_transaction(&bp->b_bio1, &vp->v_track_read);
224 vn_strategy(dp, &bp->b_bio2);
229 ffs_rawread_main(struct vnode *vp, struct uio *uio)
232 struct buf *bp, *nbp, *tbp;
234 int baseticks = ticks;
239 udata = uio->uio_iov->iov_base;
240 resid = uio->uio_resid;
241 offset = uio->uio_offset;
251 if (bp == NULL) { /* Setup first read */
252 /* XXX: Leave some bufs for swap */
253 bp = getpbuf(&ffsrawbufcnt);
254 error = ffs_rawread_readahead(vp, udata, offset, resid,
259 if (resid > bp->b_bufsize) { /* Setup fist readahead */
260 /* XXX: Leave bufs for swap */
261 if (rawreadahead != 0)
262 nbp = trypbuf(&ffsrawbufcnt);
266 nerror = ffs_rawread_readahead(
268 udata + bp->b_bufsize,
269 offset + bp->b_bufsize,
270 resid - bp->b_bufsize,
273 relpbuf(nbp, &ffsrawbufcnt);
280 biowait(&bp->b_bio1, "rawrd");
284 iolen = bp->b_bcount - bp->b_resid;
285 if (iolen == 0 && (bp->b_flags & B_ERROR) == 0) {
286 nerror = 0; /* Ignore possible beyond EOF error */
290 if ((bp->b_flags & B_ERROR) != 0) {
294 clearbiocache(&bp->b_bio2);
298 if (iolen < bp->b_bufsize) {
299 /* Incomplete read. Try to read remaining part */
300 error = ffs_rawread_readahead(
302 bp->b_bufsize - iolen, bp, &baseticks);
305 } else if (nbp != NULL) { /* Complete read with readahead */
311 clearbiocache(&nbp->b_bio2);
313 if (resid <= bp->b_bufsize) { /* No more readaheads */
314 relpbuf(nbp, &ffsrawbufcnt);
316 } else { /* Setup next readahead */
317 nerror = ffs_rawread_readahead(
318 vp, udata + bp->b_bufsize,
319 offset + bp->b_bufsize,
320 resid - bp->b_bufsize,
323 relpbuf(nbp, &ffsrawbufcnt);
327 } else if (nerror != 0) {/* Deferred Readahead error */
329 } else if (resid > 0) { /* More to read, no readahead */
330 error = ffs_rawread_readahead(vp, udata, offset,
339 relpbuf(bp, &ffsrawbufcnt);
340 if (nbp != NULL) { /* Run down readahead buffer */
341 biowait(&nbp->b_bio1, "rawrd");
343 relpbuf(nbp, &ffsrawbufcnt);
348 uio->uio_iov->iov_base = udata;
349 uio->uio_resid = resid;
350 uio->uio_offset = offset;
356 ffs_rawread(struct vnode *vp,
360 if (allowrawread != 0 &&
361 uio->uio_iovcnt == 1 &&
362 uio->uio_segflg == UIO_USERSPACE &&
363 uio->uio_resid == uio->uio_iov->iov_len &&
364 (curthread->td_flags & TDF_DEADLKTREAT) == 0) {
365 int secsize; /* Media sector size */
366 off_t filebytes; /* Bytes left of file */
367 int blockbytes; /* Bytes left of file in full blocks */
368 int partialbytes; /* Bytes in last partial block */
369 int skipbytes; /* Bytes not to read in ffs_rawread */
374 /* Only handle sector aligned reads */
376 secsize = ip->i_devvp->v_rdev->si_bsize_phys;
377 if ((uio->uio_offset & (secsize - 1)) == 0 &&
378 (uio->uio_resid & (secsize - 1)) == 0) {
380 /* Sync dirty pages and buffers if needed */
381 error = ffs_rawread_sync(vp);
385 /* Check for end of file */
386 if (ip->i_size > uio->uio_offset) {
387 filebytes = ip->i_size - uio->uio_offset;
389 /* No special eof handling needed ? */
390 if (uio->uio_resid <= filebytes) {
392 return ffs_rawread_main(vp, uio);
395 partialbytes = ((unsigned int) ip->i_size) %
397 blockbytes = (int) filebytes - partialbytes;
398 if (blockbytes > 0) {
399 skipbytes = uio->uio_resid -
401 uio->uio_resid = blockbytes;
402 error = ffs_rawread_main(vp, uio);
403 uio->uio_resid += skipbytes;
406 /* Read remaining part using buffer */