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authorTahsin Erdogan <tahsin@google.com>2017-08-05 22:41:42 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-03-18 11:17:52 +0100
commit0683564edc4e61f95663b9183ae86d6d49659ff4 (patch)
treed4029d3234568295fcf3e752d6a80b5970240610 /fs
parent43f9d23fa5a5d03a98576fb3f6700806984a4636 (diff)
ext4: inplace xattr block update fails to deduplicate blocks
commit ec00022030da5761518476096626338bd67df57a upstream. When an xattr block has a single reference, block is updated inplace and it is reinserted to the cache. Later, a cache lookup is performed to see whether an existing block has the same contents. This cache lookup will most of the time return the just inserted entry so deduplication is not achieved. Running the following test script will produce two xattr blocks which can be observed in "File ACL: " line of debugfs output: mke2fs -b 1024 -I 128 -F -O extent /dev/sdb 1G mount /dev/sdb /mnt/sdb touch /mnt/sdb/{x,y} setfattr -n user.1 -v aaa /mnt/sdb/x setfattr -n user.2 -v bbb /mnt/sdb/x setfattr -n user.1 -v aaa /mnt/sdb/y setfattr -n user.2 -v bbb /mnt/sdb/y debugfs -R 'stat x' /dev/sdb | cat debugfs -R 'stat y' /dev/sdb | cat This patch defers the reinsertion to the cache so that we can locate other blocks with the same contents. Signed-off-by: Tahsin Erdogan <tahsin@google.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Andreas Dilger <adilger@dilger.ca> Signed-off-by: Tommi Rantala <tommi.t.rantala@nokia.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/ext4/xattr.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 7c23363ecf19..8d661b3c47b6 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -828,8 +828,6 @@ ext4_xattr_block_set(handle_t *handle, struct inode *inode,
if (!IS_LAST_ENTRY(s->first))
ext4_xattr_rehash(header(s->base),
s->here);
- ext4_xattr_cache_insert(ext4_mb_cache,
- bs->bh);
}
unlock_buffer(bs->bh);
if (error == -EFSCORRUPTED)
@@ -918,6 +916,7 @@ inserted:
} else if (bs->bh && s->base == bs->bh->b_data) {
/* We were modifying this block in-place. */
ea_bdebug(bs->bh, "keeping this block");
+ ext4_xattr_cache_insert(ext4_mb_cache, bs->bh);
new_bh = bs->bh;
get_bh(new_bh);
} else {