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authorTheodore Ts'o <tytso@mit.edu>2014-07-31 06:17:17 +0400
committerTheodore Ts'o <tytso@mit.edu>2014-07-31 06:17:17 +0400
commit86f0afd463215fc3e58020493482faa4ac3a4d69 (patch)
tree977290d56ae0893d296a3b17e112cd0c65f9ab58 /fs/ext4
parentee98fa3a8b148a234600a20f7cdc2b4b37f38083 (diff)
downloadlinux-86f0afd463215fc3e58020493482faa4ac3a4d69.tar.xz
ext4: fix ext4_discard_allocated_blocks() if we can't allocate the pa struct
If there is a failure while allocating the preallocation structure, a number of blocks can end up getting marked in the in-memory buddy bitmap, and then not getting released. This can result in the following corruption getting reported by the kernel: EXT4-fs error (device sda3): ext4_mb_generate_buddy:758: group 1126, 12793 clusters in bitmap, 12729 in gd In that case, we need to release the blocks using mb_free_blocks(). Tested: fs smoke test; also demonstrated that with injected errors, the file system is no longer getting corrupted Google-Bug-Id: 16657874 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu> Cc: stable@vger.kernel.org
Diffstat (limited to 'fs/ext4')
-rw-r--r--fs/ext4/mballoc.c21
1 files changed, 20 insertions, 1 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 0e9466f9e767..956027711faf 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -3217,8 +3217,27 @@ static void ext4_mb_collect_stats(struct ext4_allocation_context *ac)
static void ext4_discard_allocated_blocks(struct ext4_allocation_context *ac)
{
struct ext4_prealloc_space *pa = ac->ac_pa;
+ struct ext4_buddy e4b;
+ int err;
- if (pa && pa->pa_type == MB_INODE_PA)
+ if (pa == NULL) {
+ err = ext4_mb_load_buddy(ac->ac_sb, ac->ac_f_ex.fe_group, &e4b);
+ if (err) {
+ /*
+ * This should never happen since we pin the
+ * pages in the ext4_allocation_context so
+ * ext4_mb_load_buddy() should never fail.
+ */
+ WARN(1, "mb_load_buddy failed (%d)", err);
+ return;
+ }
+ ext4_lock_group(ac->ac_sb, ac->ac_f_ex.fe_group);
+ mb_free_blocks(ac->ac_inode, &e4b, ac->ac_f_ex.fe_start,
+ ac->ac_f_ex.fe_len);
+ ext4_unlock_group(ac->ac_sb, ac->ac_f_ex.fe_group);
+ return;
+ }
+ if (pa->pa_type == MB_INODE_PA)
pa->pa_free += ac->ac_b_ex.fe_len;
}