Jan Kara
2009-Aug-06 21:29 UTC
[Ocfs2-devel] [PATCH] ocfs2: Fix possible deadlock when extending quota file
In OCFS2, allocator locks rank above transaction start. Thus we
cannot extend quota file from inside a transaction less we could
deadlock.
We solve the problem by starting transaction not already in
ocfs2_acquire_dquot() but only in ocfs2_local_read_dquot() and
ocfs2_global_read_dquot() and we allocate blocks to quota files before starting
the transaction. In case we crash, quota files will just have a few blocks
more but that's no problem since we just use them next time we extend the
quota file.
Signed-off-by: Jan Kara <jack at suse.cz>
---
fs/ocfs2/journal.h | 5 --
fs/ocfs2/quota_global.c | 115 +++++++++++++++++++++++------------------------
2 files changed, 57 insertions(+), 63 deletions(-)
Joel, could you please merge this fix? Thanks.
diff --git a/fs/ocfs2/journal.h b/fs/ocfs2/journal.h
index 4a4d3b5..2c3222a 100644
--- a/fs/ocfs2/journal.h
+++ b/fs/ocfs2/journal.h
@@ -363,11 +363,6 @@ static inline int ocfs2_quota_trans_credits(struct
super_block *sb)
return credits;
}
-/* Number of credits needed for removing quota structure from file */
-int ocfs2_calc_qdel_credits(struct super_block *sb, int type);
-/* Number of credits needed for initialization of new quota structure */
-int ocfs2_calc_qinit_credits(struct super_block *sb, int type);
-
/* group extend. inode update and last group update. */
#define OCFS2_GROUP_EXTEND_CREDITS (OCFS2_INODE_UPDATE_CREDITS + 1)
diff --git a/fs/ocfs2/quota_global.c b/fs/ocfs2/quota_global.c
index 8988d8b..1e24a90 100644
--- a/fs/ocfs2/quota_global.c
+++ b/fs/ocfs2/quota_global.c
@@ -224,11 +224,7 @@ ssize_t ocfs2_quota_write(struct super_block *sb, int type,
loff_t rounded_end ocfs2_align_bytes_to_blocks(sb, off + len);
- down_write(&OCFS2_I(gqinode)->ip_alloc_sem);
- err = ocfs2_extend_no_holes(gqinode, rounded_end, off);
- up_write(&OCFS2_I(gqinode)->ip_alloc_sem);
- if (err < 0)
- goto out;
+ /* Space is already allocated in ocfs2_global_read_dquot() */
err = ocfs2_simple_size_update(gqinode,
oinfo->dqi_gqi_bh,
rounded_end);
@@ -414,13 +410,36 @@ int ocfs2_global_write_info(struct super_block *sb, int
type)
return err;
}
+static int ocfs2_global_qinit_alloc(struct super_block *sb, int type)
+{
+ struct ocfs2_mem_dqinfo *oinfo = sb_dqinfo(sb, type)->dqi_priv;
+
+ /*
+ * We may need to allocate tree blocks and a leaf block but not the
+ * root block
+ */
+ return oinfo->dqi_gi.dqi_qtree_depth;
+}
+
+static int ocfs2_calc_global_qinit_credits(struct super_block *sb, int type)
+{
+ /* We modify all the allocated blocks, tree root, and info block */
+ return (ocfs2_global_qinit_alloc(sb, type) + 2) *
+ OCFS2_QUOTA_BLOCK_UPDATE_CREDITS;
+}
+
/* Read in information from global quota file and acquire a reference to it.
* dquot_acquire() has already started the transaction and locked quota file */
int ocfs2_global_read_dquot(struct dquot *dquot)
{
int err, err2, ex = 0;
- struct ocfs2_mem_dqinfo *info - sb_dqinfo(dquot->dq_sb,
dquot->dq_type)->dqi_priv;
+ struct super_block *sb = dquot->dq_sb;
+ int type = dquot->dq_type;
+ struct ocfs2_mem_dqinfo *info = sb_dqinfo(sb, type)->dqi_priv;
+ struct ocfs2_super *osb = OCFS2_SB(sb);
+ struct inode *gqinode = info->dqi_gqinode;
+ int need_alloc = ocfs2_global_qinit_alloc(sb, type);
+ handle_t *handle = NULL;
err = ocfs2_qinfo_lock(info, 0);
if (err < 0)
@@ -431,14 +450,33 @@ int ocfs2_global_read_dquot(struct dquot *dquot)
OCFS2_DQUOT(dquot)->dq_use_count++;
OCFS2_DQUOT(dquot)->dq_origspace = dquot->dq_dqb.dqb_curspace;
OCFS2_DQUOT(dquot)->dq_originodes = dquot->dq_dqb.dqb_curinodes;
+ ocfs2_qinfo_unlock(info, 0);
+
if (!dquot->dq_off) { /* No real quota entry? */
- /* Upgrade to exclusive lock for allocation */
- ocfs2_qinfo_unlock(info, 0);
- err = ocfs2_qinfo_lock(info, 1);
- if (err < 0)
- goto out_qlock;
ex = 1;
+ /*
+ * Add blocks to quota file before we start a transaction since
+ * locking allocators ranks above a transaction start
+ */
+ WARN_ON(journal_current_handle());
+ down_write(&OCFS2_I(gqinode)->ip_alloc_sem);
+ err = ocfs2_extend_no_holes(gqinode,
+ gqinode->i_size + (need_alloc << sb->s_blocksize_bits),
+ gqinode->i_size);
+ up_write(&OCFS2_I(gqinode)->ip_alloc_sem);
+ if (err < 0)
+ goto out;
+ }
+
+ handle = ocfs2_start_trans(osb,
+ ocfs2_calc_global_qinit_credits(sb, type));
+ if (IS_ERR(handle)) {
+ err = PTR_ERR(handle);
+ goto out;
}
+ err = ocfs2_qinfo_lock(info, ex);
+ if (err < 0)
+ goto out_trans;
err = qtree_write_dquot(&info->dqi_gi, dquot);
if (ex && info_dirty(sb_dqinfo(dquot->dq_sb, dquot->dq_type))) {
err2 = __ocfs2_global_write_info(dquot->dq_sb, dquot->dq_type);
@@ -450,6 +488,9 @@ out_qlock:
ocfs2_qinfo_unlock(info, 1);
else
ocfs2_qinfo_unlock(info, 0);
+out_trans:
+ if (handle)
+ ocfs2_commit_trans(osb, handle);
out:
if (err < 0)
mlog_errno(err);
@@ -647,24 +688,17 @@ out:
return status;
}
-int ocfs2_calc_qdel_credits(struct super_block *sb, int type)
+static int ocfs2_calc_qdel_credits(struct super_block *sb, int type)
{
- struct ocfs2_mem_dqinfo *oinfo;
- int features[MAXQUOTAS] = { OCFS2_FEATURE_RO_COMPAT_USRQUOTA,
- OCFS2_FEATURE_RO_COMPAT_GRPQUOTA };
-
- if (!OCFS2_HAS_RO_COMPAT_FEATURE(sb, features[type]))
- return 0;
-
- oinfo = sb_dqinfo(sb, type)->dqi_priv;
+ struct ocfs2_mem_dqinfo *oinfo = sb_dqinfo(sb, type)->dqi_priv;
/*
* We modify tree, leaf block, global info, local chunk header,
* global and local inode; OCFS2_QINFO_WRITE_CREDITS already
* accounts for inode update
*/
- return oinfo->dqi_gi.dqi_qtree_depth +
+ return (oinfo->dqi_gi.dqi_qtree_depth + 2) *
+ OCFS2_QUOTA_BLOCK_UPDATE_CREDITS +
OCFS2_QINFO_WRITE_CREDITS +
- 2 * OCFS2_QUOTA_BLOCK_UPDATE_CREDITS +
OCFS2_INODE_UPDATE_CREDITS;
}
@@ -697,36 +731,10 @@ out:
return status;
}
-int ocfs2_calc_qinit_credits(struct super_block *sb, int type)
-{
- struct ocfs2_mem_dqinfo *oinfo;
- int features[MAXQUOTAS] = { OCFS2_FEATURE_RO_COMPAT_USRQUOTA,
- OCFS2_FEATURE_RO_COMPAT_GRPQUOTA };
- struct ocfs2_dinode *lfe, *gfe;
-
- if (!OCFS2_HAS_RO_COMPAT_FEATURE(sb, features[type]))
- return 0;
-
- oinfo = sb_dqinfo(sb, type)->dqi_priv;
- gfe = (struct ocfs2_dinode *)oinfo->dqi_gqi_bh->b_data;
- lfe = (struct ocfs2_dinode *)oinfo->dqi_lqi_bh->b_data;
- /* We can extend local file + global file. In local file we
- * can modify info, chunk header block and dquot block. In
- * global file we can modify info, tree and leaf block */
- return ocfs2_calc_extend_credits(sb, &lfe->id2.i_list, 0) +
- ocfs2_calc_extend_credits(sb, &gfe->id2.i_list, 0) +
- OCFS2_LOCAL_QINFO_WRITE_CREDITS +
- 2 * OCFS2_QUOTA_BLOCK_UPDATE_CREDITS +
- oinfo->dqi_gi.dqi_qtree_depth +
- 2 * OCFS2_QUOTA_BLOCK_UPDATE_CREDITS;
-}
-
static int ocfs2_acquire_dquot(struct dquot *dquot)
{
- handle_t *handle;
struct ocfs2_mem_dqinfo *oinfo sb_dqinfo(dquot->dq_sb,
dquot->dq_type)->dqi_priv;
- struct ocfs2_super *osb = OCFS2_SB(dquot->dq_sb);
int status = 0;
mlog_entry("id=%u, type=%d", dquot->dq_id, dquot->dq_type);
@@ -735,16 +743,7 @@ static int ocfs2_acquire_dquot(struct dquot *dquot)
status = ocfs2_lock_global_qf(oinfo, 1);
if (status < 0)
goto out;
- handle = ocfs2_start_trans(osb,
- ocfs2_calc_qinit_credits(dquot->dq_sb, dquot->dq_type));
- if (IS_ERR(handle)) {
- status = PTR_ERR(handle);
- mlog_errno(status);
- goto out_ilock;
- }
status = dquot_acquire(dquot);
- ocfs2_commit_trans(osb, handle);
-out_ilock:
ocfs2_unlock_global_qf(oinfo, 1);
out:
mlog_exit(status);
--
1.6.0.2
Joel Becker
2009-Aug-10 20:38 UTC
[Ocfs2-devel] [PATCH] ocfs2: Fix possible deadlock when extending quota file
On Thu, Aug 06, 2009 at 11:29:34PM +0200, Jan Kara wrote:> In OCFS2, allocator locks rank above transaction start. Thus we > cannot extend quota file from inside a transaction less we could > deadlock. > > We solve the problem by starting transaction not already in > ocfs2_acquire_dquot() but only in ocfs2_local_read_dquot() and > ocfs2_global_read_dquot() and we allocate blocks to quota files before starting > the transaction. In case we crash, quota files will just have a few blocks > more but that's no problem since we just use them next time we extend the > quota file. > > Signed-off-by: Jan Kara <jack at suse.cz>This patch is now in the fixes branch of ocfs2.git. Joel -- Life's Little Instruction Book #43 "Never give up on somebody. Miracles happen every day." Joel Becker Principal Software Developer Oracle E-mail: joel.becker at oracle.com Phone: (650) 506-8127