Commit fc226000 authored by Stefan Roesch's avatar Stefan Roesch Committed by David Sterba
Browse files

btrfs: make prepare_pages nowait compatible 



Add nowait parameter to the prepare_pages function. In case nowait is
specified for an async buffered write request, do a nowait allocation or
return -EAGAIN.

Reviewed-by: default avatarFilipe Manana <fdmanana@suse.com>
Signed-off-by: default avatarStefan Roesch <shr@fb.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 80f9d241

fs/btrfs/file.c

+35 −8
Original line number Diff line number Diff line
@@ -1339,25 +1339,53 @@ static int prepare_uptodate_page(struct inode *inode, 
	return 0;

}



static unsigned int get_prepare_fgp_flags(bool nowait)

{

	unsigned int fgp_flags = FGP_LOCK | FGP_ACCESSED | FGP_CREAT;



	if (nowait)

		fgp_flags |= FGP_NOWAIT;



	return fgp_flags;

}



static gfp_t get_prepare_gfp_flags(struct inode *inode, bool nowait)

{

	gfp_t gfp;



	gfp = btrfs_alloc_write_mask(inode->i_mapping);

	if (nowait) {

		gfp &= ~__GFP_DIRECT_RECLAIM;

		gfp |= GFP_NOWAIT;

	}



	return gfp;

}



/*

 * this just gets pages into the page cache and locks them down.

 */

static noinline int prepare_pages(struct inode *inode, struct page **pages,

				  size_t num_pages, loff_t pos,

				  size_t write_bytes, bool force_uptodate)

				  size_t write_bytes, bool force_uptodate,

				  bool nowait)

{

	int i;

	unsigned long index = pos >> PAGE_SHIFT;

	gfp_t mask = btrfs_alloc_write_mask(inode->i_mapping);

	gfp_t mask = get_prepare_gfp_flags(inode, nowait);

	unsigned int fgp_flags = get_prepare_fgp_flags(nowait);

	int err = 0;

	int faili;



	for (i = 0; i < num_pages; i++) {

again:

		pages[i] = find_or_create_page(inode->i_mapping, index + i,

					       mask | __GFP_WRITE);

		pages[i] = pagecache_get_page(inode->i_mapping, index + i,

					      fgp_flags, mask | __GFP_WRITE);

		if (!pages[i]) {

			faili = i - 1;

			if (nowait)

				err = -EAGAIN;

			else

				err = -ENOMEM;

			goto fail;

		}
@@ -1376,7 +1404,7 @@ static noinline int prepare_pages(struct inode *inode, struct page **pages, 
						    pos + write_bytes, false);

		if (err) {

			put_page(pages[i]);

			if (err == -EAGAIN) {

			if (!nowait && err == -EAGAIN) {

				err = 0;

				goto again;

			}
@@ -1714,8 +1742,7 @@ static noinline ssize_t btrfs_buffered_write(struct kiocb *iocb, 
		 * contents of pages from loop to loop

		 */

		ret = prepare_pages(inode, pages, num_pages,

				    pos, write_bytes,

				    force_page_uptodate);

				    pos, write_bytes, force_page_uptodate, false);

		if (ret) {

			btrfs_delalloc_release_extents(BTRFS_I(inode),

						       reserve_bytes);