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ext4: prevent partial update of the extent blocks

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commit 0f2f87d51a upstream.

In the most error path of current extents updating operations are not
roll back partial updates properly when some bad things happens(.e.g in
ext4_ext_insert_extent()). So we may get an inconsistent extents tree
if journal has been aborted due to IO error, which may probability lead
to BUGON later when we accessing these extent entries in errors=continue
mode. This patch drop extent buffer's verify flag before updatng the
contents in ext4_ext_get_access(), and reset it after updating in
__ext4_ext_dirty(). After this patch we could force to check the extent
buffer if extents tree updating was break off, make sure the extents are
consistent.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Theodore Ts'o <tytso@mit.edu>
Link: https://lore.kernel.org/r/20210908120850.4012324-4-yi.zhang@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Leah Rumancik <leah.rumancik@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Zhang Yi 2021-09-08 20:08:50 +08:00 committed by Greg Kroah-Hartman
parent d57fcf0d91
commit 8583d2ea90
1 changed files with 16 additions and 2 deletions
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18
fs/ext4/extents.c
View file

@ -133,14 +133,25 @@ static int ext4_ext_truncate_extend_restart(handle_t *handle,
static int ext4_ext_get_access(handle_t *handle, struct inode *inode,
struct ext4_ext_path *path)
{
int err = 0;
if (path->p_bh) {
/* path points to block */
BUFFER_TRACE(path->p_bh, "get_write_access");
return ext4_journal_get_write_access(handle, path->p_bh);
err = ext4_journal_get_write_access(handle, path->p_bh);
/*
* The extent buffer's verified bit will be set again in
* __ext4_ext_dirty(). We could leave an inconsistent
* buffer if the extents updating procudure break off du
* to some error happens, force to check it again.
*/
if (!err)
clear_buffer_verified(path->p_bh);
}
/* path points to leaf/index in inode body */
/* we use in-core data, no need to protect them */
return 0;
return err;
}
/*
@ -160,6 +171,9 @@ int __ext4_ext_dirty(const char *where, unsigned int line, handle_t *handle,
/* path points to block */
err = __ext4_handle_dirty_metadata(where, line, handle,
inode, path->p_bh);
/* Extents updating done, re-set verified flag */
if (!err)
set_buffer_verified(path->p_bh);
} else {
/* path points to leaf/index in inode body */
err = ext4_mark_inode_dirty(handle, inode);