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Date:   Tue, 21 May 2019 16:21:39 +0800
From:   Chengguang Xu <cgxu519@...o.com.cn>
To:     jack@...e.com
Cc:     linux-ext4@...r.kernel.org, Chengguang Xu <cgxu519@...o.com.cn>
Subject: [PATCH] ext2: optimize ext2_xattr_get()

Since xattr entry names are sorted, we don't have
to continue when current entry name is greater than
target.

Signed-off-by: Chengguang Xu <cgxu519@...o.com.cn>
---
 fs/ext2/xattr.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/fs/ext2/xattr.c b/fs/ext2/xattr.c
index d21dbf297b74..f1f857b83b45 100644
--- a/fs/ext2/xattr.c
+++ b/fs/ext2/xattr.c
@@ -178,7 +178,7 @@ ext2_xattr_get(struct inode *inode, int name_index, const char *name,
 	struct ext2_xattr_entry *entry;
 	size_t name_len, size;
 	char *end;
-	int error;
+	int error, not_found;
 	struct mb_cache *ea_block_cache = EA_BLOCK_CACHE(inode);
 
 	ea_idebug(inode, "name=%d.%s, buffer=%p, buffer_size=%ld",
@@ -220,10 +220,18 @@ ext2_xattr_get(struct inode *inode, int name_index, const char *name,
 			goto bad_block;
 		if (!ext2_xattr_entry_valid(entry, inode->i_sb->s_blocksize))
 			goto bad_block;
-		if (name_index == entry->e_name_index &&
-		    name_len == entry->e_name_len &&
-		    memcmp(name, entry->e_name, name_len) == 0)
+
+		not_found = name_index - entry->e_name_index;
+		if (!not_found)
+			not_found = name_len - entry->e_name_len;
+		if (!not_found)
+			not_found = memcmp(name, entry->e_name,
+						   name_len);
+		if (!not_found)
 			goto found;
+		if (not_found < 0)
+			break;
+
 		entry = next;
 	}
 	if (ext2_xattr_cache_insert(ea_block_cache, bh))
-- 
2.20.1



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