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authorAlexey Khoroshilov <khoroshilov@ispras.ru>2013-07-01 08:12:36 -0400
committerTheodore Ts'o <tytso@mit.edu>2013-07-01 08:12:36 -0400
commit2c00ef3ee309142041c7395f42aa1d49fc9f44b9 (patch)
tree0ec1ff904065832f1c29bbd789d513d5098937ff
parent6ca792edc13c409e8d4eb9001e048264c6a2eb64 (diff)
ext4: implement error handling of ext4_mb_new_preallocation()
If memory allocation in ext4_mb_new_group_pa() is failed, it returns error code, ext4_mb_new_preallocation() propages it, but ext4_mb_new_blocks() ignores it. An observed result was: - allocation fail means ext4_mb_new_group_pa() does not update ext4_allocation_context; - ext4_mb_new_blocks() sets ext4_allocation_request->len (ar->len = ac->ac_b_ex.fe_len;) to number of blocks preallocated (512) instead of number of blocks requested (1); - that activates update cycle in ext4_splice_branch(): for (i = 1; i < blks; i++) <-- blks is 512 instead of 1 here *(where->p + i) = cpu_to_le32(current_block++); - it iterates 511 times and corrupts a chunk of memory including inode structure; - page fault happens at EXT4_SB(inode->i_sb) in ext4_mark_inode_dirty(); - system hangs with 'scheduling while atomic' BUG. The patch implements a check for ext4_mb_new_preallocation() error code and handles its failure as if ext4_mb_regular_allocator() fails. Found by Linux File System Verification project (linuxtesting.org). [ Patch restructed by tytso to make the flow of control easier to follow. ] Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
-rw-r--r--fs/ext4/mballoc.c17
1 files changed, 10 insertions, 7 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
index 1a9c22b..a9ff5e5 100644
--- a/fs/ext4/mballoc.c
+++ b/fs/ext4/mballoc.c
@@ -4406,17 +4406,20 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle,
repeat:
/* allocate space in core */
*errp = ext4_mb_regular_allocator(ac);
- if (*errp) {
- ext4_discard_allocated_blocks(ac);
- goto errout;
- }
+ if (*errp)
+ goto discard_and_exit;
/* as we've just preallocated more space than
- * user requested orinally, we store allocated
+ * user requested originally, we store allocated
* space in a special descriptor */
if (ac->ac_status == AC_STATUS_FOUND &&
- ac->ac_o_ex.fe_len < ac->ac_b_ex.fe_len)
- ext4_mb_new_preallocation(ac);
+ ac->ac_o_ex.fe_len < ac->ac_b_ex.fe_len)
+ *errp = ext4_mb_new_preallocation(ac);
+ if (*errp) {
+ discard_and_exit:
+ ext4_discard_allocated_blocks(ac);
+ goto errout;
+ }
}
if (likely(ac->ac_status == AC_STATUS_FOUND)) {
*errp = ext4_mb_mark_diskspace_used(ac, handle, reserv_clstrs);