ext4: Add mount option to set kjournald's I/O priority

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: Jens Axboe <jens.axboe@oracle.com>

diff --git a/Documentation/filesystems/ext4.txt b/Documentation/filesystems/ext4.txt
index 9ec29d86ff8b5c3494720700f1d5f8c4b9d8da46..8938949b201e43b9329677eb5cc7edaaa8696434 100644 (file)
--- a/Documentation/filesystems/ext4.txt
+++ b/Documentation/filesystems/ext4.txt
@@ -308,6 +308,13 @@ min_batch_time=usec        This parameter sets the commit time (as
                        multi-threaded, synchronous workloads on very
                        fast disks, at the cost of increasing latency.
 
+journal_ioprio=prio    The I/O priority (from 0 to 7, where 0 is the
+                       highest priorty) which should be used for I/O
+                       operations submitted by kjournald2 during a
+                       commit operation.  This defaults to 3, which is
+                       a slightly higher priority than the default I/O
+                       priority.
+
 Data Mode
 =========
 There are 3 different data modes:

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 8036392b21214fe8aed2d9c128554d9bf7359bc4..8ff8709828fd7b4c550d98ae5d51266d387f7ce8 100644 (file)
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -1013,7 +1013,7 @@ enum {
        Opt_ignore, Opt_barrier, Opt_err, Opt_resize, Opt_usrquota,
        Opt_grpquota, Opt_extents, Opt_noextents, Opt_i_version,
        Opt_stripe, Opt_delalloc, Opt_nodelalloc,
-       Opt_inode_readahead_blks
+       Opt_inode_readahead_blks, Opt_journal_ioprio
 };
 
 static const match_table_t tokens = {
@@ -1074,6 +1074,7 @@ static const match_table_t tokens = {
        {Opt_delalloc, "delalloc"},
        {Opt_nodelalloc, "nodelalloc"},
        {Opt_inode_readahead_blks, "inode_readahead_blks=%u"},
+       {Opt_journal_ioprio, "journal_ioprio=%u"},
        {Opt_err, NULL},
 };
 
@@ -1098,8 +1099,11 @@ static ext4_fsblk_t get_sb_block(void **data)
        return sb_block;
 }
 
+#define DEFAULT_JOURNAL_IOPRIO (IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, 3))
+
 static int parse_options(char *options, struct super_block *sb,
                         unsigned long *journal_devnum,
+                        unsigned int *journal_ioprio,
                         ext4_fsblk_t *n_blocks_count, int is_remount)
 {
        struct ext4_sb_info *sbi = EXT4_SB(sb);
@@ -1492,6 +1496,14 @@ set_qf_format:
                                return 0;
                        sbi->s_inode_readahead_blks = option;
                        break;
+               case Opt_journal_ioprio:
+                       if (match_int(&args[0], &option))
+                               return 0;
+                       if (option < 0 || option > 7)
+                               break;
+                       *journal_ioprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE,
+                                                           option);
+                       break;
                default:
                        printk(KERN_ERR
                               "EXT4-fs: Unrecognized mount option \"%s\" "
@@ -2035,6 +2047,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
        int features;
        __u64 blocks_count;
        int err;
+       unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
 
        sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
        if (!sbi)
@@ -2141,7 +2154,8 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
        set_opt(sbi->s_mount_opt, DELALLOC);
 
 
-       if (!parse_options((char *) data, sb, &journal_devnum, NULL, 0))
+       if (!parse_options((char *) data, sb, &journal_devnum,
+                          &journal_ioprio, NULL, 0))
                goto failed_mount;
 
        sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
@@ -2506,6 +2520,7 @@ static int ext4_fill_super(struct super_block *sb, void *data, int silent)
        default:
                break;
        }
+       set_task_ioprio(sbi->s_journal->j_task, journal_ioprio);
 
 no_journal:
 
@@ -3127,6 +3142,7 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
        unsigned long old_sb_flags;
        struct ext4_mount_options old_opts;
        ext4_group_t g;
+       unsigned int journal_ioprio = DEFAULT_JOURNAL_IOPRIO;
        int err;
 #ifdef CONFIG_QUOTA
        int i;
@@ -3145,11 +3161,14 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
        for (i = 0; i < MAXQUOTAS; i++)
                old_opts.s_qf_names[i] = sbi->s_qf_names[i];
 #endif
+       if (sbi->s_journal && sbi->s_journal->j_task->io_context)
+               journal_ioprio = sbi->s_journal->j_task->io_context->ioprio;
 
        /*
         * Allow the "check" option to be passed as a remount option.
         */
-       if (!parse_options(data, sb, NULL, &n_blocks_count, 1)) {
+       if (!parse_options(data, sb, NULL, &journal_ioprio,
+                          &n_blocks_count, 1)) {
                err = -EINVAL;
                goto restore_opts;
        }
@@ -3162,8 +3181,10 @@ static int ext4_remount(struct super_block *sb, int *flags, char *data)
 
        es = sbi->s_es;
 
-       if (sbi->s_journal)
+       if (sbi->s_journal) {
                ext4_init_journal_params(sb, sbi->s_journal);
+               set_task_ioprio(sbi->s_journal->j_task, journal_ioprio);
+       }
 
        if ((*flags & MS_RDONLY) != (sb->s_flags & MS_RDONLY) ||
                n_blocks_count > ext4_blocks_count(es)) {

diff --git a/fs/ioprio.c b/fs/ioprio.c
index 3569e0ad86a2e0ccc96cef6862b93b1e19f7b14e..1a39ac3709425bf761ae466ad7529703a4c81c7b 100644 (file)
--- a/fs/ioprio.c
+++ b/fs/ioprio.c
@@ -27,7 +27,7 @@
 #include <linux/security.h>
 #include <linux/pid_namespace.h>
 
-static int set_task_ioprio(struct task_struct *task, int ioprio)
+int set_task_ioprio(struct task_struct *task, int ioprio)
 {
        int err;
        struct io_context *ioc;
@@ -70,6 +70,7 @@ static int set_task_ioprio(struct task_struct *task, int ioprio)
        task_unlock(task);
        return err;
 }
+EXPORT_SYMBOL_GPL(set_task_ioprio);
 
 asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
 {

diff --git a/include/linux/ioprio.h b/include/linux/ioprio.h
index f98a656b17e5b4b732e57e0e70e4eb5ec53bce84..76dad48088474462b5f21deeff0414b40aca6b8e 100644 (file)
--- a/include/linux/ioprio.h
+++ b/include/linux/ioprio.h
@@ -86,4 +86,6 @@ static inline int task_nice_ioclass(struct task_struct *task)
  */
 extern int ioprio_best(unsigned short aprio, unsigned short bprio);
 
+extern int set_task_ioprio(struct task_struct *task, int ioprio);
+
 #endif