Hi Bob,
On Fri, Feb 11, 2022 at 4:51 PM Bob Peterson <[email protected]> wrote:
> Before this patch quota function bh_get called gfs2_iomap_get after it
> had locked the sd_quota_mutex. That's a problem because that holds the
> i_rw_mutex, and that lock order is different from other code that
> locks i_rw_mutex first, then the sd_quota_mutex:
I see the problem, but the patch is pretty awful. Can you resend based
on the following suggestion?
Thanks,
Andreas
---
fs/gfs2/quota.c | 39 ++++++++++++++++++---------------------
1 file changed, 18 insertions(+), 21 deletions(-)
diff --git a/fs/gfs2/quota.c b/fs/gfs2/quota.c
index 59d727a4ae2c..58fe5377d589 100644
--- a/fs/gfs2/quota.c
+++ b/fs/gfs2/quota.c
@@ -370,14 +370,12 @@ static int bh_get(struct gfs2_quota_data *qd)
unsigned int block, offset;
struct buffer_head *bh;
struct iomap iomap = { };
- int error;
+ int error = 0;
mutex_lock(&sdp->sd_quota_mutex);
-
- if (qd->qd_bh_count++) {
- mutex_unlock(&sdp->sd_quota_mutex);
- return 0;
- }
+ if (qd->qd_bh_count)
+ goto inc_out;
+ mutex_unlock(&sdp->sd_quota_mutex);
block = qd->qd_slot / sdp->sd_qc_per_block;
offset = qd->qd_slot % sdp->sd_qc_per_block;
@@ -386,32 +384,31 @@ static int bh_get(struct gfs2_quota_data *qd)
(loff_t)block << inode->i_blkbits,
i_blocksize(inode), &iomap);
if (error)
- goto fail;
- error = -ENOENT;
+ return error;
if (iomap.type != IOMAP_MAPPED)
- goto fail;
+ return -ENOENT;
error = gfs2_meta_read(ip->i_gl, iomap.addr >> inode->i_blkbits,
DIO_WAIT, 0, &bh);
if (error)
- goto fail;
- error = -EIO;
- if (gfs2_metatype_check(sdp, bh, GFS2_METATYPE_QC))
- goto fail_brelse;
+ return error;
+ if (gfs2_metatype_check(sdp, bh, GFS2_METATYPE_QC)) {
+ brelse(bh);
+ return -EIO;
+ }
+ mutex_lock(&sdp->sd_quota_mutex);
+ if (qd->qd_bh_count) {
+ brelse(bh);
+ goto inc_out;
+ }
qd->qd_bh = bh;
qd->qd_bh_qc = (struct gfs2_quota_change *)
(bh->b_data + sizeof(struct gfs2_meta_header) +
offset * sizeof(struct gfs2_quota_change));
- mutex_unlock(&sdp->sd_quota_mutex);
-
- return 0;
-
-fail_brelse:
- brelse(bh);
-fail:
- qd->qd_bh_count--;
+inc_out:
+ qd->qd_bh_count++;
mutex_unlock(&sdp->sd_quota_mutex);
return error;
}
--
2.35.1
