Commit cb843a6f authored by Chris Mason's avatar Chris Mason
Browse files

Btrfs: O_DIRECT writes via buffered writes + invaldiate 



This reworks the btrfs O_DIRECT write code a bit.  It had always fallen
back to buffered IO and done an invalidate, but needed to be updated
for the data=ordered code.  The invalidate wasn't actually removing pages
because they were still inside an ordered extent.

This also combines the O_DIRECT/O_SYNC paths where possible, and kicks
off IO in the main btrfs_file_write loop to keep the pipe down the the
disk full as we process long writes.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 323ac95b

fs/btrfs/file.c

+35 −29
Original line number Diff line number Diff line
@@ -905,6 +905,10 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf, 
	struct page *pinned[2];

	unsigned long first_index;

	unsigned long last_index;

	int will_write;



	will_write = ((file->f_flags & O_SYNC) || IS_SYNC(inode) ||

		      (file->f_flags & O_DIRECT));



	nrptrs = min((count + PAGE_CACHE_SIZE - 1) / PAGE_CACHE_SIZE,

		     PAGE_CACHE_SIZE / (sizeof(struct page *)));
@@ -1001,15 +1005,24 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf, 
		if (ret)

			goto out;



		if (will_write) {

			btrfs_fdatawrite_range(inode->i_mapping, pos,

					       pos + write_bytes - 1,

					       WB_SYNC_NONE);

		} else {

			balance_dirty_pages_ratelimited_nr(inode->i_mapping,

							   num_pages);

			if (num_pages <

			    (root->leafsize >> PAGE_CACHE_SHIFT) + 1)

				btrfs_btree_balance_dirty(root, 1);

			btrfs_throttle(root);

		}



		buf += write_bytes;

		count -= write_bytes;

		pos += write_bytes;

		num_written += write_bytes;



		balance_dirty_pages_ratelimited_nr(inode->i_mapping, num_pages);

		if (num_pages < (root->leafsize >> PAGE_CACHE_SHIFT) + 1)

			btrfs_btree_balance_dirty(root, 1);

		btrfs_throttle(root);

		cond_resched();

	}

out:
@@ -1023,37 +1036,30 @@ out_nolock: 
		page_cache_release(pinned[1]);

	*ppos = pos;



	if (num_written > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {

	if (num_written > 0 && will_write) {

		struct btrfs_trans_handle *trans;



		err = btrfs_fdatawrite_range(inode->i_mapping, start_pos,

					     start_pos + num_written -1,

					     WB_SYNC_NONE);

		if (err < 0)

			num_written = err;



		err = btrfs_wait_on_page_writeback_range(inode->i_mapping,

				 start_pos, start_pos + num_written - 1);

		if (err < 0)

		err = btrfs_wait_ordered_range(inode, start_pos, num_written);

		if (err)

			num_written = err;



		if ((file->f_flags & O_SYNC) || IS_SYNC(inode)) {

			trans = btrfs_start_transaction(root, 1);

		ret = btrfs_log_dentry_safe(trans, root, file->f_dentry);

			ret = btrfs_log_dentry_safe(trans, root,

						    file->f_dentry);

			if (ret == 0) {

				btrfs_sync_log(trans, root);

				btrfs_end_transaction(trans, root);

			} else {

				btrfs_commit_transaction(trans, root);

			}

	} else if (num_written > 0 && (file->f_flags & O_DIRECT)) {

		do_sync_mapping_range(inode->i_mapping, start_pos,

				      start_pos + num_written - 1,

				      SYNC_FILE_RANGE_WRITE |

				      SYNC_FILE_RANGE_WAIT_AFTER);

		}

		if (file->f_flags & O_DIRECT) {

			invalidate_mapping_pages(inode->i_mapping,

			      start_pos >> PAGE_CACHE_SHIFT,

			     (start_pos + num_written - 1) >> PAGE_CACHE_SHIFT);

		}

	}

	current->backing_dev_info = NULL;

	return num_written ? num_written : err;

}

fs/btrfs/ordered-data.c

+2 −1
Original line number Diff line number Diff line
@@ -397,7 +397,7 @@ void btrfs_start_ordered_extent(struct inode *inode, 
/*

 * Used to wait on ordered extents across a large range of bytes.

 */

void btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)

int btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len)

{

	u64 end;

	u64 orig_end;
@@ -451,6 +451,7 @@ again: 
		       (unsigned long long)orig_end);

		goto again;

	}

	return 0;

}



/*

fs/btrfs/ordered-data.h

+1 −1
Original line number Diff line number Diff line
@@ -135,7 +135,7 @@ struct btrfs_ordered_extent *btrfs_lookup_ordered_extent(struct inode *inode, 
							 u64 file_offset);

void btrfs_start_ordered_extent(struct inode *inode,

				struct btrfs_ordered_extent *entry, int wait);

void btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len);

int btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len);

struct btrfs_ordered_extent *

btrfs_lookup_first_ordered_extent(struct inode * inode, u64 file_offset);

int btrfs_ordered_update_i_size(struct inode *inode,

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