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ext4: fix unjournalled bg descriptor while initializing inode bitmap 

commit 61c219f581 upstream.

The first time that we allocate from an uninitialized inode allocation
bitmap, if the block allocation bitmap is also uninitalized, we need
to get write access to the block group descriptor before we start
modifying the block group descriptor flags and updating the free block
count, etc.  Otherwise, there is the potential of a bad journal
checksum (if journal checksums are enabled), and of the file system
becoming inconsistent if we crash at exactly the wrong time.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Theodore Ts'o 2014-07-05 16:28:35 -04:00 committed by Greg Kroah-Hartman
parent b03ba966f5
commit 18679495f4
1 changed files with 7 additions and 7 deletions
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14
fs/ext4/ialloc.c
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@ -851,6 +851,13 @@ got:
goto out;
}
BUFFER_TRACE(group_desc_bh, "get_write_access");
err = ext4_journal_get_write_access(handle, group_desc_bh);
if (err) {
ext4_std_error(sb, err);
goto out;
}
/* We may have to initialize the block bitmap if it isn't already */
if (ext4_has_group_desc_csum(sb) &&
gdp->bg_flags & cpu_to_le16(EXT4_BG_BLOCK_UNINIT)) {
@ -887,13 +894,6 @@ got:
}
}
BUFFER_TRACE(group_desc_bh, "get_write_access");
err = ext4_journal_get_write_access(handle, group_desc_bh);
if (err) {
ext4_std_error(sb, err);
goto out;
}
/* Update the relevant bg descriptor fields */
if (ext4_has_group_desc_csum(sb)) {
int free;