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authorTheodore Ts'o <tytso@mit.edu>2012-07-23 00:00:20 -0400
committerBen Hutchings <ben@decadent.org.uk>2012-08-02 14:37:58 +0100
commitd9af29329519c623a5a9c8b39439ed2886c9f30b (patch)
treee27da93944718b801decdd742b721916ffbe04b9
parent50e7ae34b18bb8a4911349184685fc1c4d9c0f50 (diff)
downloadlwn-d9af29329519c623a5a9c8b39439ed2886c9f30b.tar.gz
lwn-d9af29329519c623a5a9c8b39439ed2886c9f30b.zip
ext4: undo ext4_calc_metadata_amount if we fail to claim space
commit 03179fe92318e7934c180d96f12eff2cb36ef7b6 upstream. The function ext4_calc_metadata_amount() has side effects, although it's not obvious from its function name. So if we fail to claim space, regardless of whether we retry to claim the space again, or return an error, we need to undo these side effects. Otherwise we can end up incorrectly calculating the number of metadata blocks needed for the operation, which was responsible for an xfstests failure for test #271 when using an ext2 file system with delalloc enabled. Reported-by: Brian Foster <bfoster@redhat.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
-rw-r--r--fs/ext4/inode.c32
1 files changed, 21 insertions, 11 deletions
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 0d5e18f152de..8b01f9fa7648 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -1111,6 +1111,17 @@ static int ext4_da_reserve_space(struct inode *inode, ext4_lblk_t lblock)
struct ext4_inode_info *ei = EXT4_I(inode);
unsigned int md_needed;
int ret;
+ ext4_lblk_t save_last_lblock;
+ int save_len;
+
+ /*
+ * We will charge metadata quota at writeout time; this saves
+ * us from metadata over-estimation, though we may go over by
+ * a small amount in the end. Here we just reserve for data.
+ */
+ ret = dquot_reserve_block(inode, EXT4_C2B(sbi, 1));
+ if (ret)
+ return ret;
/*
* recalculate the amount of metadata blocks to reserve
@@ -1119,32 +1130,31 @@ static int ext4_da_reserve_space(struct inode *inode, ext4_lblk_t lblock)
*/
repeat:
spin_lock(&ei->i_block_reservation_lock);
+ /*
+ * ext4_calc_metadata_amount() has side effects, which we have
+ * to be prepared undo if we fail to claim space.
+ */
+ save_len = ei->i_da_metadata_calc_len;
+ save_last_lblock = ei->i_da_metadata_calc_last_lblock;
md_needed = EXT4_NUM_B2C(sbi,
ext4_calc_metadata_amount(inode, lblock));
trace_ext4_da_reserve_space(inode, md_needed);
- spin_unlock(&ei->i_block_reservation_lock);
/*
- * We will charge metadata quota at writeout time; this saves
- * us from metadata over-estimation, though we may go over by
- * a small amount in the end. Here we just reserve for data.
- */
- ret = dquot_reserve_block(inode, EXT4_C2B(sbi, 1));
- if (ret)
- return ret;
- /*
* We do still charge estimated metadata to the sb though;
* we cannot afford to run out of free blocks.
*/
if (ext4_claim_free_clusters(sbi, md_needed + 1, 0)) {
- dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
+ ei->i_da_metadata_calc_len = save_len;
+ ei->i_da_metadata_calc_last_lblock = save_last_lblock;
+ spin_unlock(&ei->i_block_reservation_lock);
if (ext4_should_retry_alloc(inode->i_sb, &retries)) {
yield();
goto repeat;
}
+ dquot_release_reservation_block(inode, EXT4_C2B(sbi, 1));
return -ENOSPC;
}
- spin_lock(&ei->i_block_reservation_lock);
ei->i_reserved_data_blocks++;
ei->i_reserved_meta_blocks += md_needed;
spin_unlock(&ei->i_block_reservation_lock);