linux-sg2042/fs/ext3
Eric Sandeen ef2b02d3e6 ext34: ensure do_split leaves enough free space in both blocks
The do_split() function for htree dir blocks is intended to split a leaf
block to make room for a new entry.  It sorts the entries in the original
block by hash value, then moves the last half of the entries to the new
block - without accounting for how much space this actually moves.  (IOW,
it moves half of the entry *count* not half of the entry *space*).  If by
chance we have both large & small entries, and we move only the smallest
entries, and we have a large new entry to insert, we may not have created
enough space for it.

The patch below stores each record size when calculating the dx_map, and
then walks the hash-sorted dx_map, calculating how many entries must be
moved to more evenly split the existing entries between the old block and
the new block, guaranteeing enough space for the new entry.

The dx_map "offs" member is reduced to u16 so that the overall map size
does not change - it is temporarily stored at the end of the new block, and
if it grows too large it may be overwritten.  By making offs and size both
u16, we won't grow the map size.

Also add a few comments to the functions involved.

This fixes the testcase reported by hooanon05@yahoo.co.jp on the
linux-ext4 list, "ext3 dir_index causes an error"

Thanks to Andreas Dilger for discussing the problem & solution with me.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Andreas Dilger <adilger@clusterfs.com>
Tested-by: Junjiro Okajima <hooanon05@yahoo.co.jp>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: <linux-ext4@vger.kernel.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-09-19 11:24:18 -07:00
..
Makefile [PATCH] ext3: uninline large functions 2006-12-07 08:39:35 -08:00
acl.c Introduce is_owner_or_cap() to wrap CAP_FOWNER use with fsuid check 2007-07-17 12:00:03 -07:00
acl.h [PATCH] Remove leftover ext3 acl declarations 2006-07-10 13:24:26 -07:00
balloc.c [PATCH] ext[234]: update documentation 2007-02-20 17:10:14 -08:00
bitmap.c [PATCH] ext3 and jbd cleanup: remove whitespace 2006-09-27 08:26:09 -07:00
dir.c readahead: split ondemand readahead interface into two functions 2007-07-19 10:04:44 -07:00
ext3_jbd.c [PATCH] ext3: uninline large functions 2006-12-07 08:39:35 -08:00
file.c sendfile: remove .sendfile from filesystems that use generic_file_sendfile() 2007-07-10 08:04:13 +02:00
fsync.c [PATCH] ext3 and jbd cleanup: remove whitespace 2006-09-27 08:26:09 -07:00
hash.c [PATCH] remove many unneeded #includes of sched.h 2007-02-14 08:09:54 -08:00
ialloc.c [PATCH] inode-diet: Eliminate i_blksize from the inode structure 2006-09-27 08:26:18 -07:00
inode.c ext3: remove extra IS_RDONLY() check 2007-07-16 09:05:48 -07:00
ioctl.c Introduce is_owner_or_cap() to wrap CAP_FOWNER use with fsuid check 2007-07-17 12:00:03 -07:00
namei.c ext34: ensure do_split leaves enough free space in both blocks 2007-09-19 11:24:18 -07:00
namei.h [PATCH] ext3: sparse fixes 2005-10-30 17:37:25 -08:00
resize.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
super.c quota: fix infinite loop 2007-09-11 17:21:19 -07:00
symlink.c [PATCH] mark struct inode_operations const 1 2007-02-12 09:48:46 -08:00
xattr.c [PATCH] "ext[34]: EA block reference count racing fix" performance fix 2007-03-23 11:01:22 -07:00
xattr.h Remove obsolete #include <linux/config.h> 2006-06-30 19:25:36 +02:00
xattr_security.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
xattr_trusted.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00
xattr_user.c header cleaning: don't include smp_lock.h when not used 2007-05-08 11:15:07 -07:00