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ext4: fix unwritten counter leakage

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ext4_set_io_unwritten_flag() will increment i_unwritten counter, so
once we mark end_io with EXT4_END_IO_UNWRITTEN we have to revert it back
on error path.

 - add missed error checks to prevent counter leakage
 - ext4_end_io_nolock() will clear EXT4_END_IO_UNWRITTEN flag to signal
   that conversion finished.
 - add BUG_ON to ext4_free_end_io() to prevent similar leakage in future.

Visible effect of this bug is that unaligned aio_stress may deadlock

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Dmitry Monakhov
2012-09-28 23:36:25 -04:00
committed by Theodore Ts'o
parent e27f41e1b7
commit 82e5422911
2 changed files with 19 additions and 8 deletions
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21
fs/ext4/extents.c
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@@ -3633,6 +3633,8 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
ret = ext4_split_unwritten_extents(handle, inode, map,
path, flags);
if (ret <= 0)
goto out;
/*
* Flag the inode(non aio case) or end_io struct (aio case)
* that this IO needs to conversion to written when IO is
@@ -3878,6 +3880,7 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
struct ext4_allocation_request ar;
ext4_io_end_t *io = ext4_inode_aio(inode);
ext4_lblk_t cluster_offset;
int set_unwritten = 0;
ext_debug("blocks %u/%u requested for inode %lu\n",
map->m_lblk, map->m_len, inode->i_ino);
@@ -4100,13 +4103,8 @@ got_allocated_blocks:
* For non asycn direct IO case, flag the inode state
* that we need to perform conversion when IO is done.
*/
if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
if (io)
ext4_set_io_unwritten_flag(inode, io);
else
ext4_set_inode_state(inode,
EXT4_STATE_DIO_UNWRITTEN);
}
if ((flags & EXT4_GET_BLOCKS_PRE_IO))
set_unwritten = 1;
if (ext4_should_dioread_nolock(inode))
map->m_flags |= EXT4_MAP_UNINIT;
}
@@ -4118,6 +4116,15 @@ got_allocated_blocks:
if (!err)
err = ext4_ext_insert_extent(handle, inode, path,
&newex, flags);
if (!err && set_unwritten) {
if (io)
ext4_set_io_unwritten_flag(inode, io);
else
ext4_set_inode_state(inode,
EXT4_STATE_DIO_UNWRITTEN);
}
if (err && free_on_err) {
int fb_flags = flags & EXT4_GET_BLOCKS_DELALLOC_RESERVE ?
EXT4_FREE_BLOCKS_NO_QUOT_UPDATE : 0;