ext4: fix journal_ioprio mount option handling

In __ext4_super() we always overwrote the user specified journal_ioprio
value with a default value, expecting parse_apply_sb_mount_options() to
later correctly set ctx->journal_ioprio to the user specified value.
However, if parse_apply_sb_mount_options() returned early because of
empty sbi->es_s->s_mount_opts, the correct journal_ioprio value was
never set.

This patch fixes __ext4_super() to only use the default value if the
user has not specified any value for journal_ioprio.

Similarly, the remount behavior was to either use journal_ioprio
value specified during initial mount, or use the default value
irrespective of the journal_ioprio value specified during remount.
This patch modifies this to first check if a new value for ioprio
has been passed during remount and apply it.  If no new value is
passed, use the value specified during initial mount.

Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Tested-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/20220418083545.45778-1-ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index b511203..4b0ea8d 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -4411,7 +4411,8 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
        int silent = fc->sb_flags & SB_SILENT;
 
        /* Set defaults for the variables that will be set during parsing */
-       ctx->journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
+       if (!(ctx->spec & EXT4_SPEC_JOURNAL_IOPRIO))
+               ctx->journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
 
        sbi->s_inode_readahead_blks = EXT4_DEF_INODE_READAHEAD_BLKS;
        sbi->s_sectors_written_start =
@@ -6278,7 +6279,6 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb)
        char *to_free[EXT4_MAXQUOTAS];
 #endif
 
-       ctx->journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
 
        /* Store the original options */
        old_sb_flags = sb->s_flags;
@@ -6304,9 +6304,14 @@ static int __ext4_remount(struct fs_context *fc, struct super_block *sb)
                } else
                        old_opts.s_qf_names[i] = NULL;
 #endif
-       if (sbi->s_journal && sbi->s_journal->j_task->io_context)
-               ctx->journal_ioprio =
-                       sbi->s_journal->j_task->io_context->ioprio;
+       if (!(ctx->spec & EXT4_SPEC_JOURNAL_IOPRIO)) {
+               if (sbi->s_journal && sbi->s_journal->j_task->io_context)
+                       ctx->journal_ioprio =
+                               sbi->s_journal->j_task->io_context->ioprio;
+               else
+                       ctx->journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
+
+       }
 
        ext4_apply_options(fc, sb);