ext4: remove unnecessary [cm]time update of quota file

It is not necessary to update [cm]time of quota file on each quota
file write and it wastes journal space and IO throughput with inode
writes. So just remove the updating from ext4_quota_write() and only
update times when quotas are being turned off. Userspace cannot get
anything reliable from quota files while they are used by the kernel
anyway.

Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

2 files changed, 16 insertions, 4 deletions

diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index e25e99bf7ee1..d0f53538a57f 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -86,8 +86,8 @@
 
 #ifdef CONFIG_QUOTA
 /* Amount of blocks needed for quota update - we know that the structure was
- * allocated so we need to update only inode+data */
-#define EXT4_QUOTA_TRANS_BLOCKS(sb) (test_opt(sb, QUOTA) ? 2 : 0)
+ * allocated so we need to update only data block */
+#define EXT4_QUOTA_TRANS_BLOCKS(sb) (test_opt(sb, QUOTA) ? 1 : 0)
 /* Amount of blocks needed for quota insert/delete - we do some block writes
  * but inode, sb and group updates are done only once */
 #define EXT4_QUOTA_INIT_BLOCKS(sb) (test_opt(sb, QUOTA) ? (DQUOT_INIT_ALLOC*\
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 22546ad7f0ae..35ff9fef68bd 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4614,11 +4614,24 @@ static int ext4_quota_on(struct super_block *sb, int type, int format_id,
 
 static int ext4_quota_off(struct super_block *sb, int type)
 {
+        struct inode *inode = sb_dqopt(sb)->files[type];
+        handle_t *handle;
+
         /* Force all delayed allocation blocks to be allocated.
          * Caller already holds s_umount sem */
         if (test_opt(sb, DELALLOC))
                 sync_filesystem(sb);
 
+        /* Update modification times of quota files when userspace can
+         * start looking at them */
+        handle = ext4_journal_start(inode, 1);
+        if (IS_ERR(handle))
+                goto out;
+        inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+        ext4_mark_inode_dirty(handle, inode);
+        ext4_journal_stop(handle);
+
+out:
         return dquot_quota_off(sb, type);
 }
 
@@ -4714,9 +4727,8 @@ out:
         if (inode->i_size < off + len) {
                 i_size_write(inode, off + len);
                 EXT4_I(inode)->i_disksize = inode->i_size;
+                ext4_mark_inode_dirty(handle, inode);
         }
-        inode->i_mtime = inode->i_ctime = CURRENT_TIME;
-        ext4_mark_inode_dirty(handle, inode);
         mutex_unlock(&inode->i_mutex);
         return len;
 }