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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/extents_status.h | |
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/extents_status.h')
0 files changed, 0 insertions, 0 deletions