From: Zhi Yong Wu <wu...@linux.vnet.ibm.com>

  FS_IOC_GET_HEAT_INFO: return a struct containing the various
metrics collected in btrfs_freq_data structs, and also return a
calculated data temperature based on those metrics. Optionally, retrieve
the temperature from the hot data hash list instead of recalculating it.

  FS_IOC_GET_HEAT_OPTS: return an integer representing the current
state of hot data tracking and migration:

0 = do nothing
1 = track frequency of access

  FS_IOC_SET_HEAT_OPTS: change the state of hot data tracking and
migration, as described above.

Signed-off-by: Zhi Yong Wu <wu...@linux.vnet.ibm.com>
---
 fs/compat_ioctl.c            |    9 +++
 fs/ioctl.c                   |  122 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/fs.h           |    1 +
 include/linux/hot_tracking.h |   22 ++++++++
 4 files changed, 154 insertions(+), 0 deletions(-)

diff --git a/fs/compat_ioctl.c b/fs/compat_ioctl.c
index f505402..820f4cc 100644
--- a/fs/compat_ioctl.c
+++ b/fs/compat_ioctl.c
@@ -57,6 +57,7 @@
 #include <linux/i2c-dev.h>
 #include <linux/atalk.h>
 #include <linux/gfp.h>
+#include <linux/hot_tracking.h>
 
 #include <net/bluetooth/bluetooth.h>
 #include <net/bluetooth/hci.h>
@@ -1398,6 +1399,11 @@ COMPATIBLE_IOCTL(TIOCSTART)
 COMPATIBLE_IOCTL(TIOCSTOP)
 #endif
 
+/*Hot data tracking*/
+COMPATIBLE_IOCTL(FS_IOC_GET_HEAT_INFO)
+COMPATIBLE_IOCTL(FS_IOC_SET_HEAT_OPTS)
+COMPATIBLE_IOCTL(FS_IOC_GET_HEAT_OPTS)
+
 /* fat 'r' ioctls. These are handled by fat with ->compat_ioctl,
    but we don't want warnings on other file systems. So declare
    them as compatible here. */
@@ -1577,6 +1583,9 @@ asmlinkage long compat_sys_ioctl(unsigned int fd, 
unsigned int cmd,
        case FIBMAP:
        case FIGETBSZ:
        case FIONREAD:
+       case FS_IOC_GET_HEAT_INFO:
+       case FS_IOC_SET_HEAT_OPTS:
+       case FS_IOC_GET_HEAT_OPTS:
                if (S_ISREG(f.file->f_path.dentry->d_inode->i_mode))
                        break;
                /*FALL THROUGH*/
diff --git a/fs/ioctl.c b/fs/ioctl.c
index 3bdad6d..35127ed 100644
--- a/fs/ioctl.c
+++ b/fs/ioctl.c
@@ -15,6 +15,7 @@
 #include <linux/writeback.h>
 #include <linux/buffer_head.h>
 #include <linux/falloc.h>
+#include "hot_tracking.h"
 
 #include <asm/ioctls.h>
 
@@ -537,6 +538,118 @@ static int ioctl_fsthaw(struct file *filp)
 }
 
 /*
+ * Retrieve information about access frequency for the given file. Return it in
+ * a userspace-friendly struct for btrfsctl (or another tool) to parse.
+ *
+ * The temperature that is returned can be "live" -- that is, recalculated when
+ * the ioctl is called -- or it can be returned from the hashtable, reflecting
+ * the (possibly old) value that the system will use when considering files
+ * for migration. This behavior is determined by hot_heat_info->live.
+ */
+static int ioctl_heat_info(struct file *file, void __user *argp)
+{
+       struct inode *file_inode;
+       struct file *file_filp;
+       struct hot_info *root = global_hot_tracking_info;
+       struct hot_heat_info *heat_info;
+       struct hot_inode_item *he;
+       int ret = 0;
+
+       heat_info = kmalloc(sizeof(struct hot_heat_info),
+                               GFP_KERNEL | GFP_NOFS);
+
+       if (copy_from_user((void *) heat_info,
+                       argp,
+                       sizeof(struct hot_heat_info)) != 0) {
+               ret = -EFAULT;
+               goto err;
+       }
+
+       file_filp = filp_open(heat_info->filename, O_RDONLY, 0);
+       file_inode = file_filp->f_dentry->d_inode;
+       filp_close(file_filp, NULL);
+
+       he = hot_inode_item_find(root, file_inode->i_ino);
+       if (!he) {
+               /* we don't have any info on this file yet */
+               ret = -ENODATA;
+               goto err;
+       }
+
+       spin_lock(&he->hot_inode.lock);
+       heat_info->avg_delta_reads =
+               (__u64) he->hot_inode.hot_freq_data.avg_delta_reads;
+       heat_info->avg_delta_writes =
+               (__u64) he->hot_inode.hot_freq_data.avg_delta_writes;
+       heat_info->last_read_time =
+               (__u64) 
timespec_to_ns(&he->hot_inode.hot_freq_data.last_read_time);
+       heat_info->last_write_time =
+               (__u64) 
timespec_to_ns(&he->hot_inode.hot_freq_data.last_write_time);
+       heat_info->num_reads =
+               (__u32) he->hot_inode.hot_freq_data.nr_reads;
+       heat_info->num_writes =
+               (__u32) he->hot_inode.hot_freq_data.nr_writes;
+
+       if (heat_info->live > 0) {
+               /*
+                * got a request for live temperature,
+                * call hot_hash_calc_temperature to recalculate
+                */
+               heat_info->temperature =
+                       hot_temperature_calculate(&he->hot_inode.hot_freq_data);
+       } else {
+               /* not live temperature, get it from the hashlist */
+               heat_info->temperature = 
he->hot_inode.hot_freq_data.last_temperature;
+       }
+       spin_unlock(&he->hot_inode.lock);
+
+       hot_inode_item_put(he);
+
+       if (copy_to_user(argp, (void *) heat_info,
+                       sizeof(struct hot_heat_info))) {
+               ret = -EFAULT;
+               goto err;
+       }
+
+err:
+       kfree(heat_info);
+       return ret;
+}
+
+static int ioctl_heat_opts(struct file *file, void __user *argp, int set)
+{
+       struct inode *inode = file->f_path.dentry->d_inode;
+       unsigned arg;
+       int ret = 0;
+
+       if (!set) {
+               arg = TRACK_THIS_INODE(inode) ? 1 : 0;
+
+               if (copy_to_user(argp, (void *) &arg, sizeof(unsigned long)) != 
0)
+                       ret = -EFAULT;
+       } else {
+               if (copy_from_user((void *) &arg, argp, sizeof(unsigned long)) 
!= 0) {
+                       ret = -EFAULT;
+               } else {
+                       switch (arg) {
+                       case 0: /* track nothing */
+                               /* set S_NOHOTDATATRACK */
+                               inode->i_flags |= S_NOHOTDATATRACK;
+                               break;
+                       case 1: /* do tracking */
+                               /* clear S_NOHOTDATATRACK */
+                               inode->i_flags &= ~S_NOHOTDATATRACK;
+                               break;
+                       default:
+                               ret = -EINVAL;
+                       }
+               }
+       }
+
+       return ret;
+}
+
+/*
  * When you add any new common ioctls to the switches above and below
  * please update compat_sys_ioctl() too.
  *
@@ -591,6 +704,15 @@ int do_vfs_ioctl(struct file *filp, unsigned int fd, 
unsigned int cmd,
        case FIGETBSZ:
                return put_user(inode->i_sb->s_blocksize, argp);
 
+       case FS_IOC_GET_HEAT_INFO:
+               return ioctl_heat_info(filp, argp);
+
+       case FS_IOC_SET_HEAT_OPTS:
+               return ioctl_heat_opts(filp, argp, 1);
+
+       case FS_IOC_GET_HEAT_OPTS:
+               return ioctl_heat_opts(filp, argp, 0);
+
        default:
                if (S_ISREG(inode->i_mode))
                        error = file_ioctl(filp, cmd, arg);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 3b1a389..c2e2d0f 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -256,6 +256,7 @@ struct inodes_stat_t {
 #define S_IMA          1024    /* Inode has an associated IMA struct */
 #define S_AUTOMOUNT    2048    /* Automount/referral quasi-directory */
 #define S_NOSEC                4096    /* no suid or xattr security attributes 
*/
+#define S_NOHOTDATATRACK (1 << 13)     /* hot data tracking */
 
 /*
  * Note that nosuid etc flags are inode-specific: setting some file-system
diff --git a/include/linux/hot_tracking.h b/include/linux/hot_tracking.h
index 6f31090..e3ca136 100644
--- a/include/linux/hot_tracking.h
+++ b/include/linux/hot_tracking.h
@@ -41,6 +41,18 @@ struct hot_freq_data {
        u32 last_temperature;
 };
 
+struct hot_heat_info {
+       __u64 avg_delta_reads;
+       __u64 avg_delta_writes;
+       __u64 last_read_time;
+       __u64 last_write_time;
+       __u32 num_reads;
+       __u32 num_writes;
+       __u32 temperature;
+       __u8 live;
+       char filename[PATH_MAX];
+};
+
 /* List heads in hot map array */
 struct hot_map_head {
        struct list_head node_list;
@@ -89,6 +101,16 @@ struct hot_info {
        struct shrinker hot_shrink;
 };
 
+/*
+ * Hot data tracking ioctls:
+ *
+ * HOT_INFO - retrieve info on frequency of access
+ */
+#define FS_IOC_GET_HEAT_INFO _IOR('f', 17, \
+                                struct hot_heat_info)
+#define FS_IOC_SET_HEAT_OPTS _IOW('f', 18, unsigned long)
+#define FS_IOC_GET_HEAT_OPTS _IOR('f', 19, unsigned long)
+
 extern struct hot_info *global_hot_tracking_info;
 
 extern void hot_track_init(struct super_block *sb);
-- 
1.7.6.5

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