Commit fcf6b1b7 authored by Dmitry Monakhov's avatar Dmitry Monakhov Committed by Theodore Ts'o
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ext4: refactor ext4_move_extents code base 



ext4_move_extents is too complex for review. It has duplicate almost
each function available in the rest of other codebase. It has useless
artificial restriction orig_offset == donor_offset. But in fact logic
of ext4_move_extents is very simple:

Iterate extents one by one (similar to ext4_fill_fiemap_extents)
   ->Iterate each page covered extent (similar to generic_perform_write)
     ->swap extents for covered by page (can be shared with IOC_MOVE_DATA)

Signed-off-by: default avatarDmitry Monakhov <dmonakhov@openvz.org>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent f8fb4f41

fs/ext4/ext4.h

+5 −0
Original line number Original line Diff line number Diff line
@@ -2740,10 +2740,15 @@ extern int ext4_find_delalloc_range(struct inode *inode, 
				    ext4_lblk_t lblk_start,

				    ext4_lblk_t lblk_start,

				    ext4_lblk_t lblk_end);

				    ext4_lblk_t lblk_end);

extern int ext4_find_delalloc_cluster(struct inode *inode, ext4_lblk_t lblk);

extern int ext4_find_delalloc_cluster(struct inode *inode, ext4_lblk_t lblk);

extern ext4_lblk_t ext4_ext_next_allocated_block(struct ext4_ext_path *path);

extern int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,

extern int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,

			__u64 start, __u64 len);

			__u64 start, __u64 len);

extern int ext4_ext_precache(struct inode *inode);

extern int ext4_ext_precache(struct inode *inode);

extern int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len);

extern int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len);

extern int ext4_swap_extents(handle_t *handle, struct inode *inode1,

				struct inode *inode2, ext4_lblk_t lblk1,

			     ext4_lblk_t lblk2,  ext4_lblk_t count,

			     int mark_unwritten,int *err);





/* move_extent.c */

/* move_extent.c */

extern void ext4_double_down_write_data_sem(struct inode *first,

extern void ext4_double_down_write_data_sem(struct inode *first,

fs/ext4/extents.c

+221 −13
Original line number Original line Diff line number Diff line
@@ -291,6 +291,19 @@ static inline int ext4_ext_space_root_idx(struct inode *inode, int check) 
	return size;

	return size;

}

}





static inline int

ext4_force_split_extent_at(handle_t *handle, struct inode *inode,

			   struct ext4_ext_path *path, ext4_lblk_t lblk,

			   int nofail)

{

	int unwritten = ext4_ext_is_unwritten(path[path->p_depth].p_ext);



	return ext4_split_extent_at(handle, inode, path, lblk, unwritten ?

			EXT4_EXT_MARK_UNWRIT1|EXT4_EXT_MARK_UNWRIT2 : 0,

			EXT4_EX_NOCACHE | EXT4_GET_BLOCKS_PRE_IO |

			(nofail ? EXT4_GET_BLOCKS_METADATA_NOFAIL:0));

}



/*

/*

 * Calculate the number of metadata blocks needed

 * Calculate the number of metadata blocks needed

 * to allocate @blocks

 * to allocate @blocks
@@ -1559,7 +1572,7 @@ found_extent: 
 * allocated block. Thus, index entries have to be consistent

 * allocated block. Thus, index entries have to be consistent

 * with leaves.

 * with leaves.

 */

 */

static ext4_lblk_t

ext4_lblk_t

ext4_ext_next_allocated_block(struct ext4_ext_path *path)

ext4_ext_next_allocated_block(struct ext4_ext_path *path)

{

{

	int depth;

	int depth;
@@ -2854,24 +2867,14 @@ again: 
		 */

		 */

		if (end >= ee_block &&

		if (end >= ee_block &&

		    end < ee_block + ext4_ext_get_actual_len(ex) - 1) {

		    end < ee_block + ext4_ext_get_actual_len(ex) - 1) {

			int split_flag = 0;



			if (ext4_ext_is_unwritten(ex))

				split_flag = EXT4_EXT_MARK_UNWRIT1 |

					     EXT4_EXT_MARK_UNWRIT2;



			/*

			/*

			 * Split the extent in two so that 'end' is the last

			 * Split the extent in two so that 'end' is the last

			 * block in the first new extent. Also we should not

			 * block in the first new extent. Also we should not

			 * fail removing space due to ENOSPC so try to use

			 * fail removing space due to ENOSPC so try to use

			 * reserved block if that happens.

			 * reserved block if that happens.

			 */

			 */

			err = ext4_split_extent_at(handle, inode, path,

			err = ext4_force_split_extent_at(handle, inode, path,

					end + 1, split_flag,

							 end + 1, 1);

					EXT4_EX_NOCACHE |

					EXT4_GET_BLOCKS_PRE_IO |

					EXT4_GET_BLOCKS_METADATA_NOFAIL);



			if (err < 0)

			if (err < 0)

				goto out;

				goto out;

		}

		}
@@ -5506,3 +5509,208 @@ out_mutex: 
	mutex_unlock(&inode->i_mutex);

	mutex_unlock(&inode->i_mutex);

	return ret;

	return ret;

}

}



/**

 * ext4_swap_extents - Swap extents between two inodes

 *

 * @inode1:	First inode

 * @inode2:	Second inode

 * @lblk1:	Start block for first inode

 * @lblk2:	Start block for second inode

 * @count:	Number of blocks to swap

 * @mark_unwritten: Mark second inode's extents as unwritten after swap

 * @erp:	Pointer to save error value

 *

 * This helper routine does exactly what is promise "swap extents". All other

 * stuff such as page-cache locking consistency, bh mapping consistency or

 * extent's data copying must be performed by caller.

 * Locking:

 * 		i_mutex is held for both inodes

 * 		i_data_sem is locked for write for both inodes

 * Assumptions:

 *		All pages from requested range are locked for both inodes

 */

int

ext4_swap_extents(handle_t *handle, struct inode *inode1,

		     struct inode *inode2, ext4_lblk_t lblk1, ext4_lblk_t lblk2,

		  ext4_lblk_t count, int unwritten, int *erp)

{

	struct ext4_ext_path *path1 = NULL;

	struct ext4_ext_path *path2 = NULL;

	int replaced_count = 0;



	BUG_ON(!rwsem_is_locked(&EXT4_I(inode1)->i_data_sem));

	BUG_ON(!rwsem_is_locked(&EXT4_I(inode2)->i_data_sem));

	BUG_ON(!mutex_is_locked(&inode1->i_mutex));

	BUG_ON(!mutex_is_locked(&inode1->i_mutex));



	*erp = ext4_es_remove_extent(inode1, lblk1, count);

	if (*erp)

		return 0;

	*erp = ext4_es_remove_extent(inode2, lblk2, count);

	if (*erp)

		return 0;



	while (count) {

		struct ext4_extent *ex1, *ex2, tmp_ex;

		ext4_lblk_t e1_blk, e2_blk;

		int e1_len, e2_len, len;

		int split = 0;



		path1 = ext4_ext_find_extent(inode1, lblk1, NULL, EXT4_EX_NOCACHE);

		if (IS_ERR(path1)) {

			*erp = PTR_ERR(path1);

			break;

		}

		path2 = ext4_ext_find_extent(inode2, lblk2, NULL, EXT4_EX_NOCACHE);

		if (IS_ERR(path2)) {

			*erp = PTR_ERR(path2);

			break;

		}

		ex1 = path1[path1->p_depth].p_ext;

		ex2 = path2[path2->p_depth].p_ext;

		/* Do we have somthing to swap ? */

		if (unlikely(!ex2 || !ex1))

			break;



		e1_blk = le32_to_cpu(ex1->ee_block);

		e2_blk = le32_to_cpu(ex2->ee_block);

		e1_len = ext4_ext_get_actual_len(ex1);

		e2_len = ext4_ext_get_actual_len(ex2);



		/* Hole handling */

		if (!in_range(lblk1, e1_blk, e1_len) ||

		    !in_range(lblk2, e2_blk, e2_len)) {

			ext4_lblk_t next1, next2;



			/* if hole after extent, then go to next extent */

			next1 = ext4_ext_next_allocated_block(path1);

			next2 = ext4_ext_next_allocated_block(path2);

			/* If hole before extent, then shift to that extent */

			if (e1_blk > lblk1)

				next1 = e1_blk;

			if (e2_blk > lblk2)

				next2 = e1_blk;

			/* Do we have something to swap */

			if (next1 == EXT_MAX_BLOCKS || next2 == EXT_MAX_BLOCKS)

				break;

			/* Move to the rightest boundary */

			len = next1 - lblk1;

			if (len < next2 - lblk2)

				len = next2 - lblk2;

			if (len > count)

				len = count;

			lblk1 += len;

			lblk2 += len;

			count -= len;

			goto repeat;

		}



		/* Prepare left boundary */

		if (e1_blk < lblk1) {

			split = 1;

			*erp = ext4_force_split_extent_at(handle, inode1,

						path1, lblk1, 0);

			if (*erp)

				break;

		}

		if (e2_blk < lblk2) {

			split = 1;

			*erp = ext4_force_split_extent_at(handle, inode2,

						path2,  lblk2, 0);

			if (*erp)

				break;

		}

		/* ext4_split_extent_at() may retult in leaf extent split,

		 * path must to be revalidated. */

		if (split)

			goto repeat;



		/* Prepare right boundary */

		len = count;

		if (len > e1_blk + e1_len - lblk1)

			len = e1_blk + e1_len - lblk1;

		if (len > e2_blk + e2_len - lblk2)

			len = e2_blk + e2_len - lblk2;



		if (len != e1_len) {

			split = 1;

			*erp = ext4_force_split_extent_at(handle, inode1,

						path1, lblk1 + len, 0);

			if (*erp)

				break;

		}

		if (len != e2_len) {

			split = 1;

			*erp = ext4_force_split_extent_at(handle, inode2,

						path2, lblk2 + len, 0);

			if (*erp)

				break;

		}

		/* ext4_split_extent_at() may retult in leaf extent split,

		 * path must to be revalidated. */

		if (split)

			goto repeat;



		BUG_ON(e2_len != e1_len);

		*erp = ext4_ext_get_access(handle, inode1, path1 + path1->p_depth);

		if (*erp)

			break;

		*erp = ext4_ext_get_access(handle, inode2, path2 + path2->p_depth);

		if (*erp)

			break;



		/* Both extents are fully inside boundaries. Swap it now */

		tmp_ex = *ex1;

		ext4_ext_store_pblock(ex1, ext4_ext_pblock(ex2));

		ext4_ext_store_pblock(ex2, ext4_ext_pblock(&tmp_ex));

		ex1->ee_len = cpu_to_le16(e2_len);

		ex2->ee_len = cpu_to_le16(e1_len);

		if (unwritten)

			ext4_ext_mark_unwritten(ex2);

		if (ext4_ext_is_unwritten(&tmp_ex))

			ext4_ext_mark_unwritten(ex1);



		ext4_ext_try_to_merge(handle, inode2, path2, ex2);

		ext4_ext_try_to_merge(handle, inode1, path1, ex1);

		*erp = ext4_ext_dirty(handle, inode2, path2 +

				      path2->p_depth);

		if (*erp)

			break;

		*erp = ext4_ext_dirty(handle, inode1, path1 +

				      path1->p_depth);

		/*

		 * Looks scarry ah..? second inode already points to new blocks,

		 * and it was successfully dirtied. But luckily error may happen

		 * only due to journal error, so full transaction will be

		 * aborted anyway.

		 */

		if (*erp)

			break;

		lblk1 += len;

		lblk2 += len;

		replaced_count += len;

		count -= len;



	repeat:

		if (path1) {

			ext4_ext_drop_refs(path1);

			kfree(path1);

			path1 = NULL;

		}

		if (path2) {

			ext4_ext_drop_refs(path2);

			kfree(path2);

			path2 = NULL;

		}

	}

	if (path1) {

		ext4_ext_drop_refs(path1);

		kfree(path1);

	}

	if (path2) {

		ext4_ext_drop_refs(path2);

		kfree(path2);

	}

	return replaced_count;

}

fs/ext4/move_extent.c

+112 −878

File changed.

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