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Commit 3fd16462 authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o
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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: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent dc8d5e56

fs/ext4/xattr.c

+18 −0
Original line number Diff line number Diff line
@@ -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;