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author | Alexey Khoroshilov <khoroshilov@ispras.ru> | 2013-07-01 08:12:36 -0400 |
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committer | Theodore Ts'o <tytso@mit.edu> | 2013-07-01 08:12:36 -0400 |
commit | 2c00ef3ee309142041c7395f42aa1d49fc9f44b9 (patch) | |
tree | 0ec1ff904065832f1c29bbd789d513d5098937ff /fs/ext4 | |
parent | 6ca792edc13c409e8d4eb9001e048264c6a2eb64 (diff) | |
download | linux-stable-2c00ef3ee309142041c7395f42aa1d49fc9f44b9.tar.gz linux-stable-2c00ef3ee309142041c7395f42aa1d49fc9f44b9.tar.bz2 linux-stable-2c00ef3ee309142041c7395f42aa1d49fc9f44b9.zip |
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>
Diffstat (limited to 'fs/ext4')
-rw-r--r-- | fs/ext4/mballoc.c | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index 1a9c22b45a01..a9ff5e5137ca 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); |