Commit fb8dd8d7 authored by Jan Kara's avatar Jan Kara

ocfs2: Fix quota locking

OCFS2 had three issues with quota locking:
a) When reading dquot from global quota file, we started a transaction while
   holding dqio_mutex which is prone to deadlocks because other paths do it
   the other way around
b) During ocfs2_sync_dquot we were not protected against concurrent writers
   on the same node. Because we first copy data to local buffer, a race
   could happen resulting in old data being written to global quota file and
   thus causing quota inconsistency after a crash.
c) ip_alloc_sem of quota files was acquired while a transaction is started
   in ocfs2_quota_write which can deadlock because we first get ip_alloc_sem
   and then start a transaction when extending quota files.

We fix the problem a) by pulling all necessary code to ocfs2_acquire_dquot
and ocfs2_release_dquot. Thus we no longer depend on generic dquot_acquire
to do the locking and can force proper lock ordering.

Problems b) and c) are fixed by locking i_mutex and ip_alloc_sem of
global quota file in ocfs2_lock_global_qf and removing ip_alloc_sem from
ocfs2_quota_read and ocfs2_quota_write.
Acked-by: default avatarJoel Becker <Joel.Becker@oracle.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
parent ae4f6ef1
......@@ -104,10 +104,11 @@ static inline int ocfs2_global_release_dquot(struct dquot *dquot)
int ocfs2_lock_global_qf(struct ocfs2_mem_dqinfo *oinfo, int ex);
void ocfs2_unlock_global_qf(struct ocfs2_mem_dqinfo *oinfo, int ex);
int ocfs2_read_quota_block(struct inode *inode, u64 v_block,
struct buffer_head **bh);
int ocfs2_validate_quota_block(struct super_block *sb, struct buffer_head *bh);
int ocfs2_read_quota_phys_block(struct inode *inode, u64 p_block,
struct buffer_head **bh);
int ocfs2_create_local_dquot(struct dquot *dquot);
int ocfs2_local_release_dquot(handle_t *handle, struct dquot *dquot);
extern const struct dquot_operations ocfs2_quota_operations;
extern struct quota_format_type ocfs2_quota_format;
......
This diff is collapsed.
......@@ -22,6 +22,7 @@
#include "dlmglue.h"
#include "quota.h"
#include "uptodate.h"
#include "super.h"
/* Number of local quota structures per block */
static inline unsigned int ol_quota_entries_per_block(struct super_block *sb)
......@@ -129,6 +130,39 @@ static int ocfs2_modify_bh(struct inode *inode, struct buffer_head *bh,
return 0;
}
/*
* Read quota block from a given logical offset.
*
* This function acquires ip_alloc_sem and thus it must not be called with a
* transaction started.
*/
static int ocfs2_read_quota_block(struct inode *inode, u64 v_block,
struct buffer_head **bh)
{
int rc = 0;
struct buffer_head *tmp = *bh;
if (i_size_read(inode) >> inode->i_sb->s_blocksize_bits <= v_block) {
ocfs2_error(inode->i_sb,
"Quota file %llu is probably corrupted! Requested "
"to read block %Lu but file has size only %Lu\n",
(unsigned long long)OCFS2_I(inode)->ip_blkno,
(unsigned long long)v_block,
(unsigned long long)i_size_read(inode));
return -EIO;
}
rc = ocfs2_read_virt_blocks(inode, v_block, 1, &tmp, 0,
ocfs2_validate_quota_block);
if (rc)
mlog_errno(rc);
/* If ocfs2_read_virt_blocks() got us a new bh, pass it up. */
if (!rc && !*bh)
*bh = tmp;
return rc;
}
/* Check whether we understand format of quota files */
static int ocfs2_local_check_quota_file(struct super_block *sb, int type)
{
......@@ -972,10 +1006,8 @@ static struct ocfs2_quota_chunk *ocfs2_local_quota_add_chunk(
}
/* Initialize chunk header */
down_read(&OCFS2_I(lqinode)->ip_alloc_sem);
status = ocfs2_extent_map_get_blocks(lqinode, oinfo->dqi_blocks,
&p_blkno, NULL, NULL);
up_read(&OCFS2_I(lqinode)->ip_alloc_sem);
if (status < 0) {
mlog_errno(status);
goto out_trans;
......@@ -1003,10 +1035,8 @@ static struct ocfs2_quota_chunk *ocfs2_local_quota_add_chunk(
ocfs2_journal_dirty(handle, bh);
/* Initialize new block with structures */
down_read(&OCFS2_I(lqinode)->ip_alloc_sem);
status = ocfs2_extent_map_get_blocks(lqinode, oinfo->dqi_blocks + 1,
&p_blkno, NULL, NULL);
up_read(&OCFS2_I(lqinode)->ip_alloc_sem);
if (status < 0) {
mlog_errno(status);
goto out_trans;
......@@ -1103,10 +1133,8 @@ static struct ocfs2_quota_chunk *ocfs2_extend_local_quota_file(
}
/* Get buffer from the just added block */
down_read(&OCFS2_I(lqinode)->ip_alloc_sem);
status = ocfs2_extent_map_get_blocks(lqinode, oinfo->dqi_blocks,
&p_blkno, NULL, NULL);
up_read(&OCFS2_I(lqinode)->ip_alloc_sem);
if (status < 0) {
mlog_errno(status);
goto out;
......@@ -1187,7 +1215,7 @@ static void olq_alloc_dquot(struct buffer_head *bh, void *private)
}
/* Create dquot in the local file for given id */
static int ocfs2_create_local_dquot(struct dquot *dquot)
int ocfs2_create_local_dquot(struct dquot *dquot)
{
struct super_block *sb = dquot->dq_sb;
int type = dquot->dq_type;
......@@ -1237,36 +1265,11 @@ out:
return status;
}
/* Create entry in local file for dquot, load data from the global file */
static int ocfs2_local_read_dquot(struct dquot *dquot)
{
int status;
mlog_entry("id=%u, type=%d\n", dquot->dq_id, dquot->dq_type);
status = ocfs2_global_read_dquot(dquot);
if (status < 0) {
mlog_errno(status);
goto out_err;
}
/* Now create entry in the local quota file */
status = ocfs2_create_local_dquot(dquot);
if (status < 0) {
mlog_errno(status);
goto out_err;
}
mlog_exit(0);
return 0;
out_err:
mlog_exit(status);
return status;
}
/* Release dquot structure from local quota file. ocfs2_release_dquot() has
* already started a transaction and obtained exclusive lock for global
* quota file. */
static int ocfs2_local_release_dquot(struct dquot *dquot)
/*
* Release dquot structure from local quota file. ocfs2_release_dquot() has
* already started a transaction and written all changes to global quota file
*/
int ocfs2_local_release_dquot(handle_t *handle, struct dquot *dquot)
{
int status;
int type = dquot->dq_type;
......@@ -1274,15 +1277,6 @@ static int ocfs2_local_release_dquot(struct dquot *dquot)
struct super_block *sb = dquot->dq_sb;
struct ocfs2_local_disk_chunk *dchunk;
int offset;
handle_t *handle = journal_current_handle();
BUG_ON(!handle);
/* First write all local changes to global file */
status = ocfs2_global_release_dquot(dquot);
if (status < 0) {
mlog_errno(status);
goto out;
}
status = ocfs2_journal_access_dq(handle,
INODE_CACHE(sb_dqopt(sb)->files[type]),
......@@ -1315,9 +1309,7 @@ static const struct quota_format_ops ocfs2_format_ops = {
.read_file_info = ocfs2_local_read_info,
.write_file_info = ocfs2_global_write_info,
.free_file_info = ocfs2_local_free_info,
.read_dqblk = ocfs2_local_read_dquot,
.commit_dqblk = ocfs2_local_write_dquot,
.release_dqblk = ocfs2_local_release_dquot,
};
struct quota_format_type ocfs2_quota_format = {
......
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