+/* 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;
+
+ if (!is_power_of_2(t))
+ 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(inode_goal, s_inode_goal);
+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);
+EXT4_RW_ATTR_SBI_UI(max_writeback_mb_bump, s_max_writeback_mb_bump);
+
+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(inode_goal),
+ 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),
+ ATTR_LIST(max_writeback_mb_bump),
+ 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,
+};
+
+/*
+ * Check whether this filesystem can be mounted based on
+ * the features present and the RDONLY/RDWR mount requested.
+ * Returns 1 if this filesystem can be mounted as requested,
+ * 0 if it cannot be.
+ */
+static int ext4_feature_set_ok(struct super_block *sb, int readonly)
+{
+ if (EXT4_HAS_INCOMPAT_FEATURE(sb, ~EXT4_FEATURE_INCOMPAT_SUPP)) {
+ ext4_msg(sb, KERN_ERR,
+ "Couldn't mount because of "
+ "unsupported optional features (%x)",
+ (le32_to_cpu(EXT4_SB(sb)->s_es->s_feature_incompat) &
+ ~EXT4_FEATURE_INCOMPAT_SUPP));
+ return 0;
+ }
+
+ if (readonly)
+ return 1;
+
+ /* Check that feature set is OK for a read-write mount */
+ if (EXT4_HAS_RO_COMPAT_FEATURE(sb, ~EXT4_FEATURE_RO_COMPAT_SUPP)) {
+ ext4_msg(sb, KERN_ERR, "couldn't mount RDWR because of "
+ "unsupported optional features (%x)",
+ (le32_to_cpu(EXT4_SB(sb)->s_es->s_feature_ro_compat) &
+ ~EXT4_FEATURE_RO_COMPAT_SUPP));
+ return 0;
+ }
+ /*
+ * Large file size enabled file system can only be mounted
+ * read-write on 32-bit systems if kernel is built with CONFIG_LBDAF
+ */
+ if (EXT4_HAS_RO_COMPAT_FEATURE(sb, EXT4_FEATURE_RO_COMPAT_HUGE_FILE)) {
+ if (sizeof(blkcnt_t) < sizeof(u64)) {
+ ext4_msg(sb, KERN_ERR, "Filesystem with huge files "
+ "cannot be mounted RDWR without "
+ "CONFIG_LBDAF");
+ return 0;
+ }
+ }
+ return 1;
+}
+