Merge tag 'xfs-buf-bulk-alloc-tag' of...

Merge tag 'xfs-buf-bulk-alloc-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs into xfs-5.14-merge2

xfs: buffer cache bulk page allocation

This patchset makes use of the new bulk page allocation interface to
reduce the overhead of allocating large numbers of pages in a
loop.

The first two patches are refactoring buffer memory allocation and
converting the uncached buffer path to use the same page allocation
path, followed by converting the page allocation path to use bulk
allocation.

The rest of the patches are then consolidation of the page
allocation and freeing code to simplify the code and remove a chunk
of unnecessary abstraction. This is largely based on a series of
changes made by Christoph Hellwig.

* tag 'xfs-buf-bulk-alloc-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs:
  xfs: merge xfs_buf_allocate_memory
  xfs: cleanup error handling in xfs_buf_get_map
  xfs: get rid of xb_to_gfp()
  xfs: simplify the b_page_count calculation
  xfs: remove ->b_offset handling for page backed buffers
  xfs: move page freeing into _xfs_buf_free_pages()
  xfs: merge _xfs_buf_get_pages()
  xfs: use alloc_pages_bulk_array() for buffers
  xfs: use xfs_buf_alloc_pages for uncached buffers
  xfs: split up xfs_buf_allocate_memory

fs/xfs/libxfs/xfs_ag.c

@@ -43,7 +43,6 @@ xfs_get_aghdr_buf(
 	if (error)
 		return error;
 
-	xfs_buf_zero(bp, 0, BBTOB(bp->b_length));
 	bp->b_bn = blkno;
 	bp->b_maps[0].bm_bn = blkno;
 	bp->b_ops = ops;

fs/xfs/xfs_buf.h

@@ -167,7 +167,8 @@ struct xfs_buf {
 	atomic_t		b_pin_count;	/* pin count */
 	atomic_t		b_io_remaining;	/* #outstanding I/O requests */
 	unsigned int		b_page_count;	/* size of page array */
-	unsigned int		b_offset;	/* page offset in first page */
+	unsigned int		b_offset;	/* page offset of b_addr,
+						   only for _XBF_KMEM buffers */
 	int			b_error;	/* error code on I/O */
 
 	/*