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Commit 2e78c927 authored by Chandan Rajendra's avatar Chandan Rajendra Committed by David Sterba
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Btrfs: __btrfs_buffered_write: Reserve/release extents aligned to block size 



Currently, the code reserves/releases extents in multiples of PAGE_CACHE_SIZE
units. Fix this by doing reservation/releases in block size units.

Signed-off-by: default avatarChandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent e410e34f

fs/btrfs/ctree.h

+3 −0
Original line number Diff line number Diff line
@@ -2353,6 +2353,9 @@ struct btrfs_map_token { 
	unsigned long offset;

};



#define BTRFS_BYTES_TO_BLKS(fs_info, bytes) \

				((bytes) >> (fs_info)->sb->s_blocksize_bits)



static inline void btrfs_init_map_token (struct btrfs_map_token *token)

{

	token->kaddr = NULL;

fs/btrfs/file.c

+30 −13
Original line number Diff line number Diff line
@@ -498,7 +498,7 @@ int btrfs_dirty_pages(struct btrfs_root *root, struct inode *inode, 
	loff_t isize = i_size_read(inode);



	start_pos = pos & ~((u64)root->sectorsize - 1);

	num_bytes = ALIGN(write_bytes + pos - start_pos, root->sectorsize);

	num_bytes = round_up(write_bytes + pos - start_pos, root->sectorsize);



	end_of_last_block = start_pos + num_bytes - 1;

	err = btrfs_set_extent_delalloc(inode, start_pos, end_of_last_block,
@@ -1379,16 +1379,19 @@ static noinline int prepare_pages(struct inode *inode, struct page **pages, 
static noinline int

lock_and_cleanup_extent_if_need(struct inode *inode, struct page **pages,

				size_t num_pages, loff_t pos,

				size_t write_bytes,

				u64 *lockstart, u64 *lockend,

				struct extent_state **cached_state)

{

	struct btrfs_root *root = BTRFS_I(inode)->root;

	u64 start_pos;

	u64 last_pos;

	int i;

	int ret = 0;



	start_pos = pos & ~((u64)PAGE_CACHE_SIZE - 1);

	last_pos = start_pos + ((u64)num_pages << PAGE_CACHE_SHIFT) - 1;

	start_pos = round_down(pos, root->sectorsize);

	last_pos = start_pos

		+ round_up(pos + write_bytes - start_pos, root->sectorsize) - 1;



	if (start_pos < inode->i_size) {

		struct btrfs_ordered_extent *ordered;
@@ -1503,6 +1506,7 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file, 


	while (iov_iter_count(i) > 0) {

		size_t offset = pos & (PAGE_CACHE_SIZE - 1);

		size_t sector_offset;

		size_t write_bytes = min(iov_iter_count(i),

					 nrptrs * (size_t)PAGE_CACHE_SIZE -

					 offset);
@@ -1511,6 +1515,8 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file, 
		size_t reserve_bytes;

		size_t dirty_pages;

		size_t copied;

		size_t dirty_sectors;

		size_t num_sectors;



		WARN_ON(num_pages > nrptrs);
@@ -1523,7 +1529,9 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file, 
			break;

		}



		reserve_bytes = num_pages << PAGE_CACHE_SHIFT;

		sector_offset = pos & (root->sectorsize - 1);

		reserve_bytes = round_up(write_bytes + sector_offset,

				root->sectorsize);



		if (BTRFS_I(inode)->flags & (BTRFS_INODE_NODATACOW |

					     BTRFS_INODE_PREALLOC)) {
@@ -1542,7 +1550,9 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file, 
				 */

				num_pages = DIV_ROUND_UP(write_bytes + offset,

							 PAGE_CACHE_SIZE);

				reserve_bytes = num_pages << PAGE_CACHE_SHIFT;

				reserve_bytes = round_up(write_bytes

							+ sector_offset,

							root->sectorsize);

				goto reserve_metadata;

			}

		}
@@ -1576,8 +1586,8 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file, 
			break;



		ret = lock_and_cleanup_extent_if_need(inode, pages, num_pages,

						      pos, &lockstart, &lockend,

						      &cached_state);

						pos, write_bytes, &lockstart,

						&lockend, &cached_state);

		if (ret < 0) {

			if (ret == -EAGAIN)

				goto again;
@@ -1612,9 +1622,16 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file, 
		 * we still have an outstanding extent for the chunk we actually

		 * managed to copy.

		 */

		if (num_pages > dirty_pages) {

			release_bytes = (num_pages - dirty_pages) <<

				PAGE_CACHE_SHIFT;

		num_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,

						reserve_bytes);

		dirty_sectors = round_up(copied + sector_offset,

					root->sectorsize);

		dirty_sectors = BTRFS_BYTES_TO_BLKS(root->fs_info,

						dirty_sectors);



		if (num_sectors > dirty_sectors) {

			release_bytes = (write_bytes - copied)

				& ~((u64)root->sectorsize - 1);

			if (copied > 0) {

				spin_lock(&BTRFS_I(inode)->lock);

				BTRFS_I(inode)->outstanding_extents++;
@@ -1633,7 +1650,8 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file, 
			}

		}



		release_bytes = dirty_pages << PAGE_CACHE_SHIFT;

		release_bytes = round_up(copied + sector_offset,

					root->sectorsize);



		if (copied > 0)

			ret = btrfs_dirty_pages(root, inode, pages,
@@ -1654,8 +1672,7 @@ static noinline ssize_t __btrfs_buffered_write(struct file *file, 


		if (only_release_metadata && copied > 0) {

			lockstart = round_down(pos, root->sectorsize);

			lockend = lockstart +

				(dirty_pages << PAGE_CACHE_SHIFT) - 1;

			lockend = round_up(pos + copied, root->sectorsize) - 1;



			set_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,

				       lockend, EXTENT_NORESERVE, NULL,