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quota: Forbid Q_GETQUOTA and Q_GETNEXTQUOTA for frozen filesystem

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Commit 7955118eaf (quota: Allow Q_GETQUOTA for frozen filesystem)
allowed Q_GETQUOTA call for frozen filesystem. It makes sense on the
first look but zero-day testing has shown that with this change ext4
warns about starting a transaction for frozen filesystem. This happens
because ext4_acquire_dquot() prepares for allocating space for new quota
structure. Although it would be possible to implement Q_GETQUOTA for
ext4 without allocating space for non-existent structures, the matter
further complicates because OCFS2 needs to update on-disk structure use
count when a new cluster node loads quota information from disk. So just
revert the change and forbid Q_GETQUOTA together with Q_GETNEXTQUOTA for
frozen filesystem. Add comment to quotactl_cmd_write() to save us from
repeating this excercise in a few years when I forget again.

Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara 2016-02-18 14:03:03 +01:00
parent 044c9b6753
commit ccf370e43e
1 changed files with 5 additions and 2 deletions
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7
fs/quota/quota.c
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@ -765,11 +765,14 @@ static int do_quotactl(struct super_block *sb, int type, int cmd, qid_t id,
/* Return 1 if 'cmd' will block on frozen filesystem */
static int quotactl_cmd_write(int cmd)
{
/*
* We cannot allow Q_GETQUOTA and Q_GETNEXTQUOTA without write access
* as dquot_acquire() may allocate space for new structure and OCFS2
* needs to increment on-disk use count.
*/
switch (cmd) {
case Q_GETFMT:
case Q_GETINFO:
case Q_GETQUOTA:
case Q_GETNEXTQUOTA:
case Q_SYNC:
case Q_XGETQSTAT:
case Q_XGETQSTATV: