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[PATCH 13/32] ext4: ext4_xattr_value_same() should return false for external data

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  [PATCH 13/32] ext4: ext4_xattr_value_same() should return false for external data Tahsin Erdogan <tahsin@google.com> - 2017-06-21 23:30 +0200
    Re: [PATCH 13/32] ext4: ext4_xattr_value_same() should return false  for external data Theodore Ts'o <tytso@mit.edu> - 2017-06-22 04:10 +0200

#1672059 — [PATCH 13/32] ext4: ext4_xattr_value_same() should return false for external data

ext4_xattr_value_same() is used as a quick optimization in case the new
xattr value is identical to the previous value. When xattr value is
stored in a xattr inode the check becomes expensive so it is better to
just assume that they are not equal.

Signed-off-by: Tahsin Erdogan <tahsin@google.com>
---
 fs/ext4/xattr.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/ext4/xattr.c b/fs/ext4/xattr.c
index 4dd8be16d175..681a9b5eefd8 100644
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -1428,6 +1428,9 @@ static int ext4_xattr_value_same(struct ext4_xattr_search *s,
 {
 	void *value;
 
+	/* When e_value_inum is set the value is stored externally. */
+	if (s->here->e_value_inum)
+		return 0;
 	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);
-- 
2.13.1.611.g7e3b11ae1-goog

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#1672247 — Re: [PATCH 13/32] ext4: ext4_xattr_value_same() should return false for external data

On Wed, Jun 21, 2017 at 02:21:23PM -0700, Tahsin Erdogan wrote:
> ext4_xattr_value_same() is used as a quick optimization in case the new
> xattr value is identical to the previous value. When xattr value is
> stored in a xattr inode the check becomes expensive so it is better to
> just assume that they are not equal.
> 
> Signed-off-by: Tahsin Erdogan <tahsin@google.com>

Thanks, added to the ext4 patch queue.

					- Ted

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