ext4: use ext4_get_block_write in buffer write

Allocate uninitialized extent before ext4 buffer write and
convert the extent to initialized after io completes.
The purpose is to make sure an extent can only be marked
initialized after it has been written with new data so
we can safely drop the i_mutex lock in ext4 DIO read without
exposing stale data. This helps to improve multi-thread DIO
read performance on high-speed disks.

Skip the nobh and data=journal mount cases to make things simple for now.

Signed-off-by: Jiaying Zhang <jiayingz@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
static void ext4_orphan_cleanup(struct super_block *sb,
				struct ext4_super_block *es)
{
	unsigned int s_flags = sb->s_flags;
	int nr_orphans = 0, nr_truncates = 0;
#ifdef CONFIG_QUOTA
	int i;
#endif
	if (!es->s_last_orphan) {
		jbd_debug(4, "no orphan inodes to clean up\n");
		return;
	}

	if (bdev_read_only(sb->s_bdev)) {
		ext4_msg(sb, KERN_ERR, "write access "
			"unavailable, skipping orphan cleanup");
		return;
	}

	if (EXT4_SB(sb)->s_mount_state & EXT4_ERROR_FS) {
		if (es->s_last_orphan)
			jbd_debug(1, "Errors on filesystem, "
				  "clearing orphan list.\n");
		es->s_last_orphan = 0;
		jbd_debug(1, "Skipping orphan recovery on fs with errors.\n");
		return;
	}

	if (s_flags & MS_RDONLY) {
		ext4_msg(sb, KERN_INFO, "orphan cleanup on readonly fs");
		sb->s_flags &= ~MS_RDONLY;
	}
#ifdef CONFIG_QUOTA
	/* Needed for iput() to work correctly and not trash data */
	sb->s_flags |= MS_ACTIVE;
	/* Turn on quotas so that they are updated correctly */
	for (i = 0; i < MAXQUOTAS; i++) {
		if (EXT4_SB(sb)->s_qf_names[i]) {
			int ret = ext4_quota_on_mount(sb, i);
			if (ret < 0)
				ext4_msg(sb, KERN_ERR,
					"Cannot turn on journaled "
					"quota: error %d", ret);
		}
	}
#endif

	while (es->s_last_orphan) {
		struct inode *inode;

		inode = ext4_orphan_get(sb, le32_to_cpu(es->s_last_orphan));
		if (IS_ERR(inode)) {
			es->s_last_orphan = 0;
			break;
		}

		list_add(&EXT4_I(inode)->i_orphan, &EXT4_SB(sb)->s_orphan);
		vfs_dq_init(inode);
		if (inode->i_nlink) {
			ext4_msg(sb, KERN_DEBUG,
				"%s: truncating inode %lu to %lld bytes",
				__func__, inode->i_ino, inode->i_size);
			jbd_debug(2, "truncating inode %lu to %lld bytes\n",
				  inode->i_ino, inode->i_size);
			ext4_truncate(inode);
			nr_truncates++;
		} else {
			ext4_msg(sb, KERN_DEBUG,
				"%s: deleting unreferenced inode %lu",
				__func__, inode->i_ino);
			jbd_debug(2, "deleting unreferenced inode %lu\n",
				  inode->i_ino);
			nr_orphans++;
		}
		iput(inode);  /* The delete magic happens here! */
	}

#define PLURAL(x) (x), ((x) == 1) ? "" : "s"

	if (nr_orphans)
		ext4_msg(sb, KERN_INFO, "%d orphan inode%s deleted",
		       PLURAL(nr_orphans));
	if (nr_truncates)
		ext4_msg(sb, KERN_INFO, "%d truncate%s cleaned up",
		       PLURAL(nr_truncates));
#ifdef CONFIG_QUOTA
	/* Turn quotas off */
	for (i = 0; i < MAXQUOTAS; i++) {
		if (sb_dqopt(sb)->files[i])
			vfs_quota_off(sb, i, 0);
	}
#endif
	sb->s_flags = s_flags; /* Restore MS_RDONLY status */
}

static void ext4_orphan_cleanup(struct super_block *sb,
				struct ext4_super_block *es)
{
	unsigned int s_flags = sb->s_flags;
	int nr_orphans = 0, nr_truncates = 0;
#ifdef CONFIG_QUOTA
	int i;
#endif
	if (!es->s_last_orphan) {
		jbd_debug(4, "no orphan inodes to clean up\n");
		return;
	}

	if (bdev_read_only(sb->s_bdev)) {
		ext4_msg(sb, KERN_ERR, "write access "
			"unavailable, skipping orphan cleanup");
		return;
	}

	if (EXT4_SB(sb)->s_mount_state & EXT4_ERROR_FS) {
		if (es->s_last_orphan)
			jbd_debug(1, "Errors on filesystem, "
				  "clearing orphan list.\n");
		es->s_last_orphan = 0;
		jbd_debug(1, "Skipping orphan recovery on fs with errors.\n");
		return;
	}

	if (s_flags & MS_RDONLY) {
		ext4_msg(sb, KERN_INFO, "orphan cleanup on readonly fs");
		sb->s_flags &= ~MS_RDONLY;
	}
#ifdef CONFIG_QUOTA
	/* Needed for iput() to work correctly and not trash data */
	sb->s_flags |= MS_ACTIVE;
	/* Turn on quotas so that they are updated correctly */
	for (i = 0; i < MAXQUOTAS; i++) {
		if (EXT4_SB(sb)->s_qf_names[i]) {
			int ret = ext4_quota_on_mount(sb, i);
			if (ret < 0)
				ext4_msg(sb, KERN_ERR,
					"Cannot turn on journaled "
					"quota: error %d", ret);
		}
	}
#endif

	while (es->s_last_orphan) {
		struct inode *inode;

		inode = ext4_orphan_get(sb, le32_to_cpu(es->s_last_orphan));
		if (IS_ERR(inode)) {
			es->s_last_orphan = 0;
			break;
		}

		list_add(&EXT4_I(inode)->i_orphan, &EXT4_SB(sb)->s_orphan);
		vfs_dq_init(inode);
		if (inode->i_nlink) {
			ext4_msg(sb, KERN_DEBUG,
				"%s: truncating inode %lu to %lld bytes",
				__func__, inode->i_ino, inode->i_size);
			jbd_debug(2, "truncating inode %lu to %lld bytes\n",
				  inode->i_ino, inode->i_size);
			ext4_truncate(inode);
			nr_truncates++;
		} else {
			ext4_msg(sb, KERN_DEBUG,
				"%s: deleting unreferenced inode %lu",
				__func__, inode->i_ino);
			jbd_debug(2, "deleting unreferenced inode %lu\n",
				  inode->i_ino);
			nr_orphans++;
		}
		iput(inode);  /* The delete magic happens here! */
	}

#define PLURAL(x) (x), ((x) == 1) ? "" : "s"

	if (nr_orphans)
		ext4_msg(sb, KERN_INFO, "%d orphan inode%s deleted",
		       PLURAL(nr_orphans));
	if (nr_truncates)
		ext4_msg(sb, KERN_INFO, "%d truncate%s cleaned up",
		       PLURAL(nr_truncates));
#ifdef CONFIG_QUOTA
	/* Turn quotas off */
	for (i = 0; i < MAXQUOTAS; i++) {
		if (sb_dqopt(sb)->files[i])
			vfs_quota_off(sb, i, 0);
	}
#endif
	sb->s_flags = s_flags; /* Restore MS_RDONLY status */
}
