Commit 03bd8b9b authored by Dmitry Monakhov's avatar Dmitry Monakhov Committed by Theodore Ts'o
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ext4: move_extent code cleanup 



- Remove usless checks, because it is too late to check that inode != NULL
  at the moment it was referenced several times.
- Double lock routines looks very ugly and locking ordering relays on
  order of i_ino, but other kernel code rely on order of pointers.
  Let's make them simple and clean.
- check that inodes belongs to the same SB as soon as possible.

Signed-off-by: default avatarDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
parent 0acdb887

fs/ext4/move_extent.c

+47 −120
Original line number Diff line number Diff line
@@ -140,56 +140,22 @@ mext_next_extent(struct inode *inode, struct ext4_ext_path *path, 
	return 1;

}



/**

 * mext_check_null_inode - NULL check for two inodes

 *

 * If inode1 or inode2 is NULL, return -EIO. Otherwise, return 0.

 */

static int

mext_check_null_inode(struct inode *inode1, struct inode *inode2,

		      const char *function, unsigned int line)

{

	int ret = 0;



	if (inode1 == NULL) {

		__ext4_error(inode2->i_sb, function, line,

			"Both inodes should not be NULL: "

			"inode1 NULL inode2 %lu", inode2->i_ino);

		ret = -EIO;

	} else if (inode2 == NULL) {

		__ext4_error(inode1->i_sb, function, line,

			"Both inodes should not be NULL: "

			"inode1 %lu inode2 NULL", inode1->i_ino);

		ret = -EIO;

	}

	return ret;

}



/**

 * double_down_write_data_sem - Acquire two inodes' write lock of i_data_sem

 *

 * @orig_inode:		original inode structure

 * @donor_inode:	donor inode structure

 * Acquire write lock of i_data_sem of the two inodes (orig and donor) by

 * i_ino order.

 * Acquire write lock of i_data_sem of the two inodes

 */

static void

double_down_write_data_sem(struct inode *orig_inode, struct inode *donor_inode)

double_down_write_data_sem(struct inode *first, struct inode *second)

{

	struct inode *first = orig_inode, *second = donor_inode;



	/*

	 * Use the inode number to provide the stable locking order instead

	 * of its address, because the C language doesn't guarantee you can

	 * compare pointers that don't come from the same array.

	 */

	if (donor_inode->i_ino < orig_inode->i_ino) {

		first = donor_inode;

		second = orig_inode;

	}



	if (first < second) {

		down_write(&EXT4_I(first)->i_data_sem);

		down_write_nested(&EXT4_I(second)->i_data_sem, SINGLE_DEPTH_NESTING);

	} else {

		down_write(&EXT4_I(second)->i_data_sem);

		down_write_nested(&EXT4_I(first)->i_data_sem, SINGLE_DEPTH_NESTING);



	}

}



/**
@@ -969,14 +935,6 @@ mext_check_arguments(struct inode *orig_inode, 
		return -EINVAL;

	}



	/* Files should be in the same ext4 FS */

	if (orig_inode->i_sb != donor_inode->i_sb) {

		ext4_debug("ext4 move extent: The argument files "

			"should be in same FS [ino:orig %lu, donor %lu]\n",

			orig_inode->i_ino, donor_inode->i_ino);

		return -EINVAL;

	}



	/* Ext4 move extent supports only extent based file */

	if (!(ext4_test_inode_flag(orig_inode, EXT4_INODE_EXTENTS))) {

		ext4_debug("ext4 move extent: orig file is not extents "
@@ -1072,35 +1030,19 @@ mext_check_arguments(struct inode *orig_inode, 
 * @inode1:	the inode structure

 * @inode2:	the inode structure

 *

 * Lock two inodes' i_mutex by i_ino order.

 * If inode1 or inode2 is NULL, return -EIO. Otherwise, return 0.

 * Lock two inodes' i_mutex

 */

static int

static void

mext_inode_double_lock(struct inode *inode1, struct inode *inode2)

{

	int ret = 0;



	BUG_ON(inode1 == NULL && inode2 == NULL);



	ret = mext_check_null_inode(inode1, inode2, __func__, __LINE__);

	if (ret < 0)

		goto out;



	if (inode1 == inode2) {

		mutex_lock(&inode1->i_mutex);

		goto out;

	}



	if (inode1->i_ino < inode2->i_ino) {

	BUG_ON(inode1 == inode2);

	if (inode1 < inode2) {

		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_PARENT);

		mutex_lock_nested(&inode2->i_mutex, I_MUTEX_CHILD);

	} else {

		mutex_lock_nested(&inode2->i_mutex, I_MUTEX_PARENT);

		mutex_lock_nested(&inode1->i_mutex, I_MUTEX_CHILD);

	}



out:

	return ret;

}



/**
@@ -1109,28 +1051,13 @@ out: 
 * @inode1:     the inode that is released first

 * @inode2:     the inode that is released second

 *

 * If inode1 or inode2 is NULL, return -EIO. Otherwise, return 0.

 */



static int

static void

mext_inode_double_unlock(struct inode *inode1, struct inode *inode2)

{

	int ret = 0;



	BUG_ON(inode1 == NULL && inode2 == NULL);



	ret = mext_check_null_inode(inode1, inode2, __func__, __LINE__);

	if (ret < 0)

		goto out;



	if (inode1)

	mutex_unlock(&inode1->i_mutex);



	if (inode2 && inode2 != inode1)

	mutex_unlock(&inode2->i_mutex);



out:

	return ret;

}



/**
@@ -1187,16 +1114,23 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, 
	ext4_lblk_t block_end, seq_start, add_blocks, file_end, seq_blocks = 0;

	ext4_lblk_t rest_blocks;

	pgoff_t orig_page_offset = 0, seq_end_page;

	int ret1, ret2, depth, last_extent = 0;

	int ret, depth, last_extent = 0;

	int blocks_per_page = PAGE_CACHE_SIZE >> orig_inode->i_blkbits;

	int data_offset_in_page;

	int block_len_in_page;

	int uninit;



	/* orig and donor should be different file */

	if (orig_inode->i_ino == donor_inode->i_ino) {

	if (orig_inode->i_sb != donor_inode->i_sb) {

		ext4_debug("ext4 move extent: The argument files "

			"should be in same FS [ino:orig %lu, donor %lu]\n",

			orig_inode->i_ino, donor_inode->i_ino);

		return -EINVAL;

	}



	/* orig and donor should be different inodes */

	if (orig_inode == donor_inode) {

		ext4_debug("ext4 move extent: The argument files should not "

			"be same file [ino:orig %lu, donor %lu]\n",

			"be same inode [ino:orig %lu, donor %lu]\n",

			orig_inode->i_ino, donor_inode->i_ino);

		return -EINVAL;

	}
@@ -1210,16 +1144,14 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, 
	}



	/* Protect orig and donor inodes against a truncate */

	ret1 = mext_inode_double_lock(orig_inode, donor_inode);

	if (ret1 < 0)

		return ret1;

	mext_inode_double_lock(orig_inode, donor_inode);



	/* Protect extent tree against block allocations via delalloc */

	double_down_write_data_sem(orig_inode, donor_inode);

	/* Check the filesystem environment whether move_extent can be done */

	ret1 = mext_check_arguments(orig_inode, donor_inode, orig_start,

	ret = mext_check_arguments(orig_inode, donor_inode, orig_start,

				    donor_start, &len);

	if (ret1)

	if (ret)

		goto out;



	file_end = (i_size_read(orig_inode) - 1) >> orig_inode->i_blkbits;
@@ -1227,13 +1159,13 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, 
	if (file_end < block_end)

		len -= block_end - file_end;



	ret1 = get_ext_path(orig_inode, block_start, &orig_path);

	if (ret1)

	ret = get_ext_path(orig_inode, block_start, &orig_path);

	if (ret)

		goto out;



	/* Get path structure to check the hole */

	ret1 = get_ext_path(orig_inode, block_start, &holecheck_path);

	if (ret1)

	ret = get_ext_path(orig_inode, block_start, &holecheck_path);

	if (ret)

		goto out;



	depth = ext_depth(orig_inode);
@@ -1252,13 +1184,13 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, 
		last_extent = mext_next_extent(orig_inode,

					holecheck_path, &ext_cur);

		if (last_extent < 0) {

			ret1 = last_extent;

			ret = last_extent;

			goto out;

		}

		last_extent = mext_next_extent(orig_inode, orig_path,

							&ext_dummy);

		if (last_extent < 0) {

			ret1 = last_extent;

			ret = last_extent;

			goto out;

		}

		seq_start = le32_to_cpu(ext_cur->ee_block);
@@ -1272,7 +1204,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, 
	if (le32_to_cpu(ext_cur->ee_block) > block_end) {

		ext4_debug("ext4 move extent: The specified range of file "

							"may be the hole\n");

		ret1 = -EINVAL;

		ret = -EINVAL;

		goto out;

	}
@@ -1292,7 +1224,7 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, 
		last_extent = mext_next_extent(orig_inode, holecheck_path,

						&ext_cur);

		if (last_extent < 0) {

			ret1 = last_extent;

			ret = last_extent;

			break;

		}

		add_blocks = ext4_ext_get_actual_len(ext_cur);
@@ -1349,18 +1281,18 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, 
						orig_page_offset,

						data_offset_in_page,

						block_len_in_page, uninit,

						&ret1);

						&ret);



			/* Count how many blocks we have exchanged */

			*moved_len += block_len_in_page;

			if (ret1 < 0)

			if (ret < 0)

				break;

			if (*moved_len > len) {

				EXT4_ERROR_INODE(orig_inode,

					"We replaced blocks too much! "

					"sum of replaced: %llu requested: %llu",

					*moved_len, len);

				ret1 = -EIO;

				ret = -EIO;

				break;

			}
@@ -1374,22 +1306,22 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp, 
		}



		double_down_write_data_sem(orig_inode, donor_inode);

		if (ret1 < 0)

		if (ret < 0)

			break;



		/* Decrease buffer counter */

		if (holecheck_path)

			ext4_ext_drop_refs(holecheck_path);

		ret1 = get_ext_path(orig_inode, seq_start, &holecheck_path);

		if (ret1)

		ret = get_ext_path(orig_inode, seq_start, &holecheck_path);

		if (ret)

			break;

		depth = holecheck_path->p_depth;



		/* Decrease buffer counter */

		if (orig_path)

			ext4_ext_drop_refs(orig_path);

		ret1 = get_ext_path(orig_inode, seq_start, &orig_path);

		if (ret1)

		ret = get_ext_path(orig_inode, seq_start, &orig_path);

		if (ret)

			break;



		ext_cur = holecheck_path[depth].p_ext;
@@ -1412,12 +1344,7 @@ out: 
		kfree(holecheck_path);

	}

	double_up_write_data_sem(orig_inode, donor_inode);

	ret2 = mext_inode_double_unlock(orig_inode, donor_inode);



	if (ret1)

		return ret1;

	else if (ret2)

		return ret2;

	mext_inode_double_unlock(orig_inode, donor_inode);



	return 0;

	return ret;

}

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