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authorJan Kara <jack@suse.cz>2016-02-22 22:43:04 -0500
committerTheodore Ts'o <tytso@mit.edu>2016-02-22 22:43:04 -0500
commit3fd164629d25b04f291a79a013dcc7ce1a301269 (patch)
tree52e5cd01818b7d390361d5f1a459b1c1edd8ad5d /fs/ext4
parentdc8d5e565f00c9442fa1cbf9acc115475628527c (diff)
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ext4: shortcut setting of xattr to the same value
When someone tried to set xattr to the same value (i.e., not changing anything) we did all the work of removing original xattr, possibly breaking references to shared xattr block, inserting new xattr, and merging xattr blocks again. Since this is not so rare operation and it is relatively cheap for us to detect this case, check for this and shortcut xattr setting in that case. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/xattr.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index c6af8a7a436a..b661ae8332e3 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1096,6 +1096,17 @@ static int ext4_xattr_ibody_set(handle_t *handle, struct inode *inode,
return 0;
}
+static int ext4_xattr_value_same(struct ext4_xattr_search *s,
+ struct ext4_xattr_info *i)
+{
+ void *value;
+
+ if (le32_to_cpu(s->here->e_value_size) != i->value_len)
+ return 0;
+ value = ((void *)s->base) + le16_to_cpu(s->here->e_value_offs);
+ return !memcmp(value, i->value, i->value_len);
+}
+
/*
* ext4_xattr_set_handle()
*
@@ -1172,6 +1183,13 @@ ext4_xattr_set_handle(handle_t *handle, struct inode *inode, int name_index,
else if (!bs.s.not_found)
error = ext4_xattr_block_set(handle, inode, &i, &bs);
} else {
+ error = 0;
+ /* Xattr value did not change? Save us some work and bail out */
+ if (!is.s.not_found && ext4_xattr_value_same(&is.s, &i))
+ goto cleanup;
+ if (!bs.s.not_found && ext4_xattr_value_same(&bs.s, &i))
+ goto cleanup;
+
error = ext4_xattr_ibody_set(handle, inode, &i, &is);
if (!error && !bs.s.not_found) {
i.value = NULL;