From: Zheng Liu <redacted>

Define a new mount option to add VFS hot tracking support in order to use it in
ext4.

CC: Zhi Yong Wu <redacted>
Signed-off-by: Zheng Liu <redacted>
---
Hi Zhiyong,

Here is a try to add hot tracking support in ext4.  I do some simple tests and
it works well.

Regards,
Zheng

 fs/ext4/ext4.h  |  3 +++
 fs/ext4/super.c | 15 ++++++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 3c20de1..f6cff1e 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h

@@ -1298,6 +1298,9 @@ struct ext4_sb_info {

        /* Precomputed FS UUID checksum for seeding other checksums */
        __u32 s_csum_seed;
+
+       /* Enable hot tracking or not */
+       int s_hottrack_enable;
 };

 static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)

diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 80928f7..1506dc3 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c

@@ -43,6 +43,7 @@

 #include <linux/kthread.h>
 #include <linux/freezer.h>
+#include <linux/hot_tracking.h>

 #include "ext4.h"
 #include "ext4_extents.h"

@@ -864,6 +865,8 @@ static void ext4_put_super(struct super_block *sb)
        ext4_ext_release(sb);
        ext4_xattr_put_super(sb);

+       if (sbi->s_hottrack_enable)
+               hot_track_exit(sb);
        if (!(sb->s_flags & MS_RDONLY)) {
                EXT4_CLEAR_INCOMPAT_FEATURE(sb, EXT4_FEATURE_INCOMPAT_RECOVER);
                es->s_state = cpu_to_le16(sbi->s_mount_state);

@@ -1222,7 +1225,7 @@ enum {
        Opt_inode_readahead_blks, Opt_journal_ioprio,
        Opt_dioread_nolock, Opt_dioread_lock,
        Opt_discard, Opt_nodiscard, Opt_init_itable, Opt_noinit_itable,
-       Opt_max_dir_size_kb,
+       Opt_max_dir_size_kb, Opt_hottrack,
 };

 static const match_table_t tokens = {

@@ -1297,6 +1300,7 @@ static const match_table_t tokens = {
        {Opt_init_itable, "init_itable"},
        {Opt_noinit_itable, "noinit_itable"},
        {Opt_max_dir_size_kb, "max_dir_size_kb=%u"},
+       {Opt_hottrack, "hot_track"},
        {Opt_removed, "check=none"},    /* mount option from ext2/3 */
        {Opt_removed, "nocheck"},       /* mount option from ext2/3 */
        {Opt_removed, "reservation"},   /* mount option from ext2/3 */

@@ -1478,6 +1482,7 @@ static const struct mount_opts {
        {Opt_jqfmt_vfsv0, QFMT_VFS_V0, MOPT_QFMT},
        {Opt_jqfmt_vfsv1, QFMT_VFS_V1, MOPT_QFMT},
        {Opt_max_dir_size_kb, 0, MOPT_GTE0},
+       {Opt_hottrack, 0, MOPT_GTE0},
        {Opt_err, 0, 0}
 };

@@ -1595,6 +1600,14 @@ static int handle_mount_opt(struct super_block *sb, char *opt, int token,
                        sbi->s_li_wait_mult = arg;
                } else if (token == Opt_max_dir_size_kb) {
                        sbi->s_max_dir_size_kb = arg;
+               } else if (token == Opt_hottrack) {
+                       if (hot_track_init(sb)) {
+                               ext4_msg(sb, KERN_ERR,
+                                        "EXT4-fs: hot tracking initialization"
+                                        " failed");
+                               return -1;
+                       }
+                       sbi->s_hottrack_enable = 1;
                } else if (token == Opt_stripe) {
                        sbi->s_stripe = arg;
                } else if (m->flags & MOPT_DATAJ) {
--

1.7.12.rc2.18.g61b472e