[PATCH 3.2 071/164] ext4: move check under lock scope to close a race.
From: Ben Hutchings
Date: Sat Aug 01 2015 - 20:12:52 EST
3.2.70-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Davide Italiano <dccitaliano@xxxxxxxxx>
commit 280227a75b56ab5d35854f3a77ef74a7ad56a203 upstream.
fallocate() checks that the file is extent-based and returns
EOPNOTSUPP in case is not. Other tasks can convert from and to
indirect and extent so it's safe to check only after grabbing
the inode mutex.
Signed-off-by: Davide Italiano <dccitaliano@xxxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
[bwh: Backported to 3.2:
- Adjust context
- Add the 'out' label]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
fs/ext4/extents.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4470,13 +4470,6 @@ long ext4_fallocate(struct file *file, i
struct ext4_map_blocks map;
unsigned int credits, blkbits = inode->i_blkbits;
- /*
- * currently supporting (pre)allocate mode for extent-based
- * files _only_
- */
- if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)))
- return -EOPNOTSUPP;
-
/* Return error if mode is not supported */
if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
return -EOPNOTSUPP;
@@ -4497,6 +4490,15 @@ long ext4_fallocate(struct file *file, i
*/
credits = ext4_chunk_trans_blocks(inode, max_blocks);
mutex_lock(&inode->i_mutex);
+
+ /*
+ * We only support preallocation for extent-based files only
+ */
+ if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
+ ret = -EOPNOTSUPP;
+ goto out;
+ }
+
ret = inode_newsize_ok(inode, (len + offset));
if (ret) {
mutex_unlock(&inode->i_mutex);
@@ -4553,6 +4555,7 @@ retry:
ret = 0;
goto retry;
}
+out:
mutex_unlock(&inode->i_mutex);
trace_ext4_fallocate_exit(inode, offset, max_blocks,
ret > 0 ? ret2 : ret);
--
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