Commit 3a90983d authored by Yan, Zheng's avatar Yan, Zheng Committed by Chris Mason
Browse files

Btrfs: Fix page count calculation 



take offset of start position into account when calculating page count.

Signed-off-by: default avatarYan, Zheng <zheng.z.yan@intel.com>
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 8e4eef7a

fs/btrfs/file.c

+4 −4
Original line number Diff line number Diff line
@@ -991,8 +991,8 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb, 
		size_t write_bytes = min(iov_iter_count(&i),

					 nrptrs * (size_t)PAGE_CACHE_SIZE -

					 offset);

		size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>

					PAGE_CACHE_SHIFT;

		size_t num_pages = (write_bytes + offset +

				    PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;



		WARN_ON(num_pages > nrptrs);

		memset(pages, 0, sizeof(struct page *) * nrptrs);
@@ -1022,7 +1022,7 @@ static ssize_t btrfs_file_aio_write(struct kiocb *iocb, 


		copied = btrfs_copy_from_user(pos, num_pages,

					   write_bytes, pages, &i);

		dirty_pages = (copied + PAGE_CACHE_SIZE - 1) >>

		dirty_pages = (copied + offset + PAGE_CACHE_SIZE - 1) >>

				PAGE_CACHE_SHIFT;



		if (num_pages > dirty_pages) {