Last year, mpi@ implemented VFS read clustering for MSDOSFS in
sys/msdosfs/denode.h 1.28
sys/msdosfs/msdosfs_vnops.c 1.105
This caused regressions when doing seeks past the end of the file and had
to be reverted.
I have now written a test that catches the bug (committed in
regress/sys/fileops) and got a fix that does not break the test:
There was some confusion as to what block sizes are used in file
operations. Openbsd seems to be more like netbsd than like freebsd.
See msdosfs_vnops.c 1.62 in freebsd:
Author: msmith <msm...@freebsd.org>
Date: Sun Mar 1 21:26:09 1998 +0000
Fix mmap() on msdosfs. In the words of the submitter:
|In the process of evaluating the getpages/putpages issues I discovered
|that mmap on MSDOSFS does not work. This is because I blindly merged
|NetBSD changes in msdosfs_bmap and msdosfs_strategy. Apparently, their
|blocksize is always DEV_BSIZE (even in files), while in FreeBSD
|blocksize in files is v_mount->mnt_stat.f_iosize (i.e. clustersize in
|MSDOSFS case). The patch is below.
Submitted by: Dmitrij Tejblum <d...@tejblum.dnttm.rssi.ru>
The diff is meant to be on top of mpi's diff (or on top of a revert of the
revert 1.113). I can send the complete diff if that's preferred.
diff --git a/sys/msdosfs/msdosfs_vnops.c b/sys/msdosfs/msdosfs_vnops.c
index 45a479fb646..46ff2736ca4 100644
--- sys/msdosfs/msdosfs_vnops.c
+++ sys/msdosfs/msdosfs_vnops.c
@@ -516,7 +516,7 @@ msdosfs_read(void *v)
int isadir, error = 0;
uint32_t n, diff, size, on;
struct buf *bp;
- daddr_t cn;
+ daddr_t cn, bn;
/*
* If they didn't ask for any data, then we are done.
@@ -556,10 +556,11 @@ msdosfs_read(void *v)
return (error);
error = bread(pmp->pm_devvp, cn, size, &bp);
} else {
+ bn = de_cn2bn(pmp, cn);
if (de_cn2off(pmp, cn + 1) >= dep->de_FileSize)
- error = bread(vp, cn, size, &bp);
+ error = bread(vp, bn, size, &bp);
else
- error = bread_cluster(vp, cn, size, &bp);
+ error = bread_cluster(vp, bn, size, &bp);
}
n = min(n, pmp->pm_bpcluster - bp->b_resid);
if (error) {
@@ -588,7 +589,7 @@ msdosfs_write(void *v)
uint32_t osize;
int error = 0;
uint32_t count, lastcn;
- daddr_t cn;
+ daddr_t cn, bn;
struct buf *bp;
int ioflag = ap->a_ioflag;
struct uio *uio = ap->a_uio;
@@ -681,18 +682,19 @@ msdosfs_write(void *v)
* or we write the cluster from its start beyond EOF,
* then no need to read data from disk.
*/
- bp = getblk(thisvp, cn, pmp->pm_bpcluster, 0, 0);
+ bn = de_cn2bn(pmp, cn);
+ bp = getblk(thisvp, bn, pmp->pm_bpcluster, 0, 0);
clrbuf(bp);
/*
* Do the bmap now, since pcbmap needs buffers
* for the fat table. (see msdosfs_strategy)
*/
if (bp->b_blkno == bp->b_lblkno) {
- error = pcbmap(dep, bp->b_lblkno, &cn, 0, 0);
+ error = pcbmap(dep,
+ de_bn2cn(pmp, bp->b_lblkno),
+ &bp->b_blkno, 0, 0);
if (error)
bp->b_blkno = -1;
- else
- bp->b_blkno = cn;
}
if (bp->b_blkno == -1) {
brelse(bp);
@@ -705,7 +707,8 @@ msdosfs_write(void *v)
* The block we need to write into exists, so
* read it in.
*/
- error = bread(thisvp, cn, pmp->pm_bpcluster, &bp);
+ bn = de_cn2bn(pmp, cn);
+ error = bread(thisvp, bn, pmp->pm_bpcluster, &bp);
if (error) {
brelse(bp);
break;
@@ -1820,7 +1823,8 @@ msdosfs_strategy(void *v)
* don't allow files with holes, so we shouldn't ever see this.
*/
if (bp->b_blkno == bp->b_lblkno) {
- error = pcbmap(dep, bp->b_lblkno, &bp->b_blkno, 0, 0);
+ error = pcbmap(dep, de_bn2cn(dep->de_pmp, bp->b_lblkno),
+ &bp->b_blkno, 0, 0);
if (error)
bp->b_blkno = -1;
if (bp->b_blkno == -1)
