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The UFS filesystem requires that the last block of a file always be

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allocated. When shortening the length of a file in which the new end
of the file contains a hole, the hole must have a block allocated.

Reported by: Maxim Sobolev
Reviewed by: kib
Tested by:   Peter Holm
This commit is contained in:
mckusick 2016-02-24 01:58:40 +00:00
parent bd6a91854e
commit 6a020d6c89
1 changed files with 60 additions and 17 deletions
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77
sys/ufs/ffs/ffs_inode.c
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@ -184,7 +184,7 @@ ffs_truncate(vp, length, flags, cred)
struct inode *ip;
ufs2_daddr_t bn, lbn, lastblock, lastiblock[NIADDR], indir_lbn[NIADDR];
ufs2_daddr_t oldblks[NDADDR + NIADDR], newblks[NDADDR + NIADDR];
ufs2_daddr_t count, blocksreleased = 0, datablocks;
ufs2_daddr_t count, blocksreleased = 0, datablocks, blkno;
struct bufobj *bo;
struct fs *fs;
struct buf *bp;
@ -192,7 +192,7 @@ ffs_truncate(vp, length, flags, cred)
int softdeptrunc, journaltrunc;
int needextclean, extblocks;
int offset, size, level, nblocks;
int i, error, allerror;
int i, error, allerror, indiroff;
off_t osize;
ip = VTOI(vp);
@ -329,16 +329,57 @@ ffs_truncate(vp, length, flags, cred)
ip->i_flag |= IN_CHANGE | IN_UPDATE;
return (ffs_update(vp, !DOINGASYNC(vp)));
}
if (DOINGSOFTDEP(vp)) {
/*
* Lookup block number for a given offset. Zero length files
* have no blocks, so return a blkno of -1.
*/
lbn = lblkno(fs, length - 1);
if (length == 0) {
blkno = -1;
} else if (lbn < NDADDR) {
blkno = DIP(ip, i_db[lbn]);
} else {
error = UFS_BALLOC(vp, lblktosize(fs, (off_t)lbn), fs->fs_bsize,
cred, BA_METAONLY, &bp);
if (error)
return (error);
indiroff = (lbn - NDADDR) % NINDIR(fs);
if (ip->i_ump->um_fstype == UFS1)
blkno = ((ufs1_daddr_t *)(bp->b_data))[indiroff];
else
blkno = ((ufs2_daddr_t *)(bp->b_data))[indiroff];
/*
* If the block number is non-zero, then the indirect block
* must have been previously allocated and need not be written.
* If the block number is zero, then we may have allocated
* the indirect block and hence need to write it out.
*/
if (blkno != 0)
brelse(bp);
else if (DOINGSOFTDEP(vp) || DOINGASYNC(vp))
bdwrite(bp);
else
bwrite(bp);
}
/*
* If the block number at the new end of the file is zero,
* then we must allocate it to ensure that the last block of
* the file is allocated. Soft updates does not handle this
* case, so here we have to clean up the soft updates data
* structures describing the allocation past the truncation
* point. Finding and deallocating those structures is a lot of
* work. Since partial truncation with a hole at the end occurs
* rarely, we solve the problem by syncing the file so that it
* will have no soft updates data structures left.
*/
if (blkno == 0 && (error = ffs_syncvnode(vp, MNT_WAIT, 0)) != 0)
return (error);
if (blkno != 0 && DOINGSOFTDEP(vp)) {
if (softdeptrunc == 0 && journaltrunc == 0) {
/*
* If a file is only partially truncated, then
* we have to clean up the data structures
* describing the allocation past the truncation
* point. Finding and deallocating those structures
* is a lot of work. Since partial truncation occurs
* rarely, we solve the problem by syncing the file
* so that it will have no data structures left.
* If soft updates cannot handle this truncation,
* clean up soft dependency data structures and
* fall through to the synchronous truncation.
*/
if ((error = ffs_syncvnode(vp, MNT_WAIT, 0)) != 0)
return (error);
@ -358,15 +399,17 @@ ffs_truncate(vp, length, flags, cred)
}
}
/*
* Shorten the size of the file. If the file is not being
* truncated to a block boundary, the contents of the
* partial block following the end of the file must be
* zero'ed in case it ever becomes accessible again because
* of subsequent file growth. Directories however are not
* Shorten the size of the file. If the last block of the
* shortened file is unallocated, we must allocate it.
* Additionally, if the file is not being truncated to a
* block boundary, the contents of the partial block
* following the end of the file must be zero'ed in
* case it ever becomes accessible again because of
* subsequent file growth. Directories however are not
* zero'ed as they should grow back initialized to empty.
*/
offset = blkoff(fs, length);
if (offset == 0) {
if (blkno != 0 && offset == 0) {
ip->i_size = length;
DIP_SET(ip, i_size, length);
} else {
@ -390,7 +433,7 @@ ffs_truncate(vp, length, flags, cred)
ip->i_size = length;
DIP_SET(ip, i_size, length);
size = blksize(fs, ip, lbn);
if (vp->v_type != VDIR)
if (vp->v_type != VDIR && offset != 0)
bzero((char *)bp->b_data + offset,
(u_int)(size - offset));
/* Kirk's code has reallocbuf(bp, size, 1) here */