1 files changed, 58 insertions, 16 deletions

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 056474b7b8e0..8553dfb310af 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -242,27 +242,44 @@ static void ext4_put_nojournal(handle_t *handle)
  * journal_end calls result in the superblock being marked dirty, so
  * that sync() will call the filesystem's write_super callback if
  * appropriate.
+ *
+ * To avoid j_barrier hold in userspace when a user calls freeze(),
+ * ext4 prevents a new handle from being started by s_frozen, which
+ * is in an upper layer.
  */
 handle_t *ext4_journal_start_sb(struct super_block *sb, int nblocks)
 {
         journal_t *journal;
+        handle_t  *handle;
 
         if (sb->s_flags & MS_RDONLY)
                 return ERR_PTR(-EROFS);
 
-        vfs_check_frozen(sb, SB_FREEZE_TRANS);
-        /* Special case here: if the journal has aborted behind our
-         * backs (eg. EIO in the commit thread), then we still need to
-         * take the FS itself readonly cleanly. */
         journal = EXT4_SB(sb)->s_journal;
-        if (journal) {
-                if (is_journal_aborted(journal)) {
-                        ext4_abort(sb, "Detected aborted journal");
-                        return ERR_PTR(-EROFS);
-                }
-                return jbd2_journal_start(journal, nblocks);
+        handle = ext4_journal_current_handle();
+
+        /*
+         * If a handle has been started, it should be allowed to
+         * finish, otherwise deadlock could happen between freeze
+         * and others(e.g. truncate) due to the restart of the
+         * journal handle if the filesystem is forzen and active
+         * handles are not stopped.
+         */
+        if (!handle)
+                vfs_check_frozen(sb, SB_FREEZE_TRANS);
+
+        if (!journal)
+                return ext4_get_nojournal();
+        /*
+         * Special case here: if the journal has aborted behind our
+         * backs (eg. EIO in the commit thread), then we still need to
+         * take the FS itself readonly cleanly.
+         */
+        if (is_journal_aborted(journal)) {
+                ext4_abort(sb, "Detected aborted journal");
+                return ERR_PTR(-EROFS);
         }
-        return ext4_get_nojournal();
+        return jbd2_journal_start(journal, nblocks);
 }
 
 /*
@@ -2975,6 +2992,12 @@ static int ext4_register_li_request(struct super_block *sb,
         mutex_unlock(&ext4_li_info->li_list_mtx);
 
         sbi->s_li_request = elr;
+        /*
+         * set elr to NULL here since it has been inserted to
+         * the request_list and the removal and free of it is
+         * handled by ext4_clear_request_list from now on.
+         */
+        elr = NULL;
 
         if (!(ext4_li_info->li_state & EXT4_LAZYINIT_RUNNING)) {
                 ret = ext4_run_lazyinit_thread();
@@ -3385,6 +3408,10 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
         get_random_bytes(&sbi->s_next_generation, sizeof(u32));
         spin_lock_init(&sbi->s_next_gen_lock);
 
+        init_timer(&sbi->s_err_report);
+        sbi->s_err_report.function = print_daily_error_info;
+        sbi->s_err_report.data = (unsigned long) sb;
+
         err = percpu_counter_init(&sbi->s_freeblocks_counter,
                         ext4_count_free_blocks(sb));
         if (!err) {
@@ -3646,9 +3673,6 @@ no_journal:
                  "Opts: %s%s%s", descr, sbi->s_es->s_mount_opts,
                  *sbi->s_es->s_mount_opts ? "; " : "", orig_data);
 
-        init_timer(&sbi->s_err_report);
-        sbi->s_err_report.function = print_daily_error_info;
-        sbi->s_err_report.data = (unsigned long) sb;
         if (es->s_error_count)
                 mod_timer(&sbi->s_err_report, jiffies + 300*HZ); /* 5 minutes */
 
@@ -3672,6 +3696,7 @@ failed_mount_wq:
                 sbi->s_journal = NULL;
         }
 failed_mount3:
+        del_timer(&sbi->s_err_report);
         if (sbi->s_flex_groups) {
                 if (is_vmalloc_addr(sbi->s_flex_groups))
                         vfree(sbi->s_flex_groups);
@@ -4138,6 +4163,11 @@ static int ext4_sync_fs(struct super_block *sb, int wait)
 /*
  * LVM calls this function before a (read-only) snapshot is created.  This
  * gives us a chance to flush the journal completely and mark the fs clean.
+ *
+ * Note that only this function cannot bring a filesystem to be in a clean
+ * state independently, because ext4 prevents a new handle from being started
+ * by @sb->s_frozen, which stays in an upper layer.  It thus needs help from
+ * the upper layer.
  */
 static int ext4_freeze(struct super_block *sb)
 {
@@ -4614,11 +4644,24 @@ 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 +4757,8 @@ 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;
 }