ext4: Add sysfs support

Add basic sysfs support so that information about the mounted
filesystem and various tuning parameters can be accessed via
/sys/fs/ext4/<dev>/*.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

2 files changed, 209 insertions, 0 deletions

diff --git a/fs/ext4/ext4_sb.h b/fs/ext4/ext4_sb.h
index 50ab1169c378..57b71fefbccf 100644
--- a/fs/ext4/ext4_sb.h
+++ b/fs/ext4/ext4_sb.h
@@ -64,6 +64,8 @@ struct ext4_sb_info {
         struct percpu_counter s_dirtyblocks_counter;
         struct blockgroup_lock *s_blockgroup_lock;
         struct proc_dir_entry *s_proc;
+        struct kobject s_kobj;
+        struct completion s_kobj_unregister;
 
         /* Journaling */
         struct inode *s_journal_inode;
diff --git a/fs/ext4/super.c b/fs/ext4/super.c
index 30fc27cdf8fc..2883d4318c22 100644
--- a/fs/ext4/super.c
+++ b/fs/ext4/super.c
@@ -35,6 +35,7 @@
 #include <linux/quotaops.h>
 #include <linux/seq_file.h>
 #include <linux/proc_fs.h>
+#include <linux/ctype.h>
 #include <linux/marker.h>
 #include <linux/log2.h>
 #include <linux/crc16.h>
@@ -48,6 +49,7 @@
 #include "group.h"
 
 struct proc_dir_entry *ext4_proc_root;
+static struct kset *ext4_kset;
 
 static int ext4_load_journal(struct super_block *, struct ext4_super_block *,
                              unsigned long journal_devnum);
@@ -580,6 +582,7 @@ static void ext4_put_super(struct super_block *sb)
                 remove_proc_entry("inode_readahead_blks", sbi->s_proc);
                 remove_proc_entry(sb->s_id, ext4_proc_root);
         }
+        kobject_del(&sbi->s_kobj);
 
         for (i = 0; i < sbi->s_gdb_count; i++)
                 brelse(sbi->s_group_desc[i]);
@@ -615,6 +618,16 @@ static void ext4_put_super(struct super_block *sb)
                 ext4_blkdev_remove(sbi);
         }
         sb->s_fs_info = NULL;
+        /*
+         * Now that we are completely done shutting down the
+         * superblock, we need to actually destroy the kobject.
+         */
+        unlock_kernel();
+        unlock_super(sb);
+        kobject_put(&sbi->s_kobj);
+        wait_for_completion(&sbi->s_kobj_unregister);
+        lock_super(sb);
+        lock_kernel();
         kfree(sbi->s_blockgroup_lock);
         kfree(sbi);
         return;
@@ -1464,6 +1477,11 @@ set_qf_format:
                                 return 0;
                         if (option < 0 || option > (1 << 30))
                                 return 0;
+                        if (option & (option - 1)) {
+                                printk(KERN_ERR "EXT4-fs: inode_readahead_blks"
+                                       " must be a power of 2\n");
+                                return 0;
+                        }
                         sbi->s_inode_readahead_blks = option;
                         break;
                 case Opt_journal_ioprio:
@@ -1992,6 +2010,181 @@ static unsigned long ext4_get_stripe_size(struct ext4_sb_info *sbi)
         return 0;
 }
 
+/* sysfs supprt */
+
+struct ext4_attr {
+        struct attribute attr;
+        ssize_t (*show)(struct ext4_attr *, struct ext4_sb_info *, char *);
+        ssize_t (*store)(struct ext4_attr *, struct ext4_sb_info *, 
+                         const char *, size_t);
+        int offset;
+};
+
+static int parse_strtoul(const char *buf,
+                unsigned long max, unsigned long *value)
+{
+        char *endp;
+
+        while (*buf && isspace(*buf))
+                buf++;
+        *value = simple_strtoul(buf, &endp, 0);
+        while (*endp && isspace(*endp))
+                endp++;
+        if (*endp || *value > max)
+                return -EINVAL;
+
+        return 0;
+}
+
+static ssize_t delayed_allocation_blocks_show(struct ext4_attr *a,
+                                              struct ext4_sb_info *sbi,
+                                              char *buf)
+{
+        return snprintf(buf, PAGE_SIZE, "%llu\n",
+                        (s64) percpu_counter_sum(&sbi->s_dirtyblocks_counter));
+}
+
+static ssize_t session_write_kbytes_show(struct ext4_attr *a,
+                                         struct ext4_sb_info *sbi, char *buf)
+{
+        struct super_block *sb = sbi->s_buddy_cache->i_sb;
+
+        return snprintf(buf, PAGE_SIZE, "%lu\n",
+                        (part_stat_read(sb->s_bdev->bd_part, sectors[1]) -
+                         sbi->s_sectors_written_start) >> 1);
+}
+
+static ssize_t lifetime_write_kbytes_show(struct ext4_attr *a,
+                                          struct ext4_sb_info *sbi, char *buf)
+{
+        struct super_block *sb = sbi->s_buddy_cache->i_sb;
+
+        return snprintf(buf, PAGE_SIZE, "%llu\n",
+                        sbi->s_kbytes_written + 
+                        ((part_stat_read(sb->s_bdev->bd_part, sectors[1]) -
+                          EXT4_SB(sb)->s_sectors_written_start) >> 1));
+}
+
+static ssize_t inode_readahead_blks_store(struct ext4_attr *a,
+                                          struct ext4_sb_info *sbi,
+                                          const char *buf, size_t count)
+{
+        unsigned long t;
+
+        if (parse_strtoul(buf, 0x40000000, &t))
+                return -EINVAL;
+
+        /* inode_readahead_blks must be a power of 2 */
+        if (t & (t-1))
+                return -EINVAL;
+
+        sbi->s_inode_readahead_blks = t;
+        return count;
+}
+
+static ssize_t sbi_ui_show(struct ext4_attr *a,
+                                struct ext4_sb_info *sbi, char *buf)
+{
+        unsigned int *ui = (unsigned int *) (((char *) sbi) + a->offset);
+
+        return snprintf(buf, PAGE_SIZE, "%u\n", *ui);
+}
+
+static ssize_t sbi_ui_store(struct ext4_attr *a,
+                            struct ext4_sb_info *sbi,
+                            const char *buf, size_t count)
+{
+        unsigned int *ui = (unsigned int *) (((char *) sbi) + a->offset);
+        unsigned long t;
+
+        if (parse_strtoul(buf, 0xffffffff, &t))
+                return -EINVAL;
+        *ui = t;
+        return count;
+}
+
+#define EXT4_ATTR_OFFSET(_name,_mode,_show,_store,_elname) \
+static struct ext4_attr ext4_attr_##_name = {                   \
+        .attr = {.name = __stringify(_name), .mode = _mode },   \
+        .show   = _show,                                        \
+        .store  = _store,                                       \
+        .offset = offsetof(struct ext4_sb_info, _elname),       \
+}
+#define EXT4_ATTR(name, mode, show, store) \
+static struct ext4_attr ext4_attr_##name = __ATTR(name, mode, show, store)
+
+#define EXT4_RO_ATTR(name) EXT4_ATTR(name, 0444, name##_show, NULL)
+#define EXT4_RW_ATTR(name) EXT4_ATTR(name, 0644, name##_show, name##_store)
+#define EXT4_RW_ATTR_SBI_UI(name, elname)       \
+        EXT4_ATTR_OFFSET(name, 0644, sbi_ui_show, sbi_ui_store, elname)
+#define ATTR_LIST(name) &ext4_attr_##name.attr
+
+EXT4_RO_ATTR(delayed_allocation_blocks);
+EXT4_RO_ATTR(session_write_kbytes);
+EXT4_RO_ATTR(lifetime_write_kbytes);
+EXT4_ATTR_OFFSET(inode_readahead_blks, 0644, sbi_ui_show,
+                 inode_readahead_blks_store, s_inode_readahead_blks);
+EXT4_RW_ATTR_SBI_UI(mb_stats, s_mb_stats);
+EXT4_RW_ATTR_SBI_UI(mb_max_to_scan, s_mb_max_to_scan);
+EXT4_RW_ATTR_SBI_UI(mb_min_to_scan, s_mb_min_to_scan);
+EXT4_RW_ATTR_SBI_UI(mb_order2_req, s_mb_order2_reqs);
+EXT4_RW_ATTR_SBI_UI(mb_stream_req, s_mb_stream_request);
+EXT4_RW_ATTR_SBI_UI(mb_group_prealloc, s_mb_group_prealloc);
+
+static struct attribute *ext4_attrs[] = {
+        ATTR_LIST(delayed_allocation_blocks),
+        ATTR_LIST(session_write_kbytes),
+        ATTR_LIST(lifetime_write_kbytes),
+        ATTR_LIST(inode_readahead_blks),
+        ATTR_LIST(mb_stats),
+        ATTR_LIST(mb_max_to_scan),
+        ATTR_LIST(mb_min_to_scan),
+        ATTR_LIST(mb_order2_req),
+        ATTR_LIST(mb_stream_req),
+        ATTR_LIST(mb_group_prealloc),
+        NULL,
+};
+
+static ssize_t ext4_attr_show(struct kobject *kobj,
+                              struct attribute *attr, char *buf)
+{
+        struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
+                                                s_kobj);
+        struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);
+
+        return a->show ? a->show(a, sbi, buf) : 0;
+}
+
+static ssize_t ext4_attr_store(struct kobject *kobj,
+                               struct attribute *attr,
+                               const char *buf, size_t len)
+{
+        struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
+                                                s_kobj);
+        struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);
+
+        return a->store ? a->store(a, sbi, buf, len) : 0;
+}
+
+static void ext4_sb_release(struct kobject *kobj)
+{
+        struct ext4_sb_info *sbi = container_of(kobj, struct ext4_sb_info,
+                                                s_kobj);
+        complete(&sbi->s_kobj_unregister);
+}
+
+
+static struct sysfs_ops ext4_attr_ops = {
+        .show   = ext4_attr_show,
+        .store  = ext4_attr_store,
+};
+
+static struct kobj_type ext4_ktype = {
+        .default_attrs  = ext4_attrs,
+        .sysfs_ops      = &ext4_attr_ops,
+        .release        = ext4_sb_release,
+};
+
 static int ext4_fill_super(struct super_block *sb, void *data, int silent)
                                 __releases(kernel_lock)
                                 __acquires(kernel_lock)
@@ -2575,6 +2768,16 @@ no_journal:
                 goto failed_mount4;
         }
 
+        sbi->s_kobj.kset = ext4_kset;
+        init_completion(&sbi->s_kobj_unregister);
+        err = kobject_init_and_add(&sbi->s_kobj, &ext4_ktype, NULL,
+                                   "%s", sb->s_id);
+        if (err) {
+                ext4_mb_release(sb);
+                ext4_ext_release(sb);
+                goto failed_mount4;
+        };
+
         /*
          * akpm: core read_super() calls in here with the superblock locked.
          * That deadlocks, because orphan cleanup needs to lock the superblock
@@ -3734,6 +3937,9 @@ static int __init init_ext4_fs(void)
 {
         int err;
 
+        ext4_kset = kset_create_and_add("ext4", NULL, fs_kobj);
+        if (!ext4_kset)
+                return -ENOMEM;
         ext4_proc_root = proc_mkdir("fs/ext4", NULL);
         err = init_ext4_mballoc();
         if (err)
@@ -3775,6 +3981,7 @@ static void __exit exit_ext4_fs(void)
         exit_ext4_xattr();
         exit_ext4_mballoc();
         remove_proc_entry("fs/ext4", NULL);
+        kset_unregister(ext4_kset);
 }
 
 MODULE_AUTHOR("Remy Card, Stephen Tweedie, Andrew Morton, Andreas Dilger, Theodore Ts'o and others");