From 0a683794ace283984ae95ea6796f37b5f3afc446 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Tue, 1 Jun 2021 13:40:02 +1000 Subject: [PATCH] xfs: split up xfs_buf_allocate_memory Based on a patch from Christoph Hellwig. This splits out the heap allocation and page allocation portions of the buffer memory allocation into two separate helper functions. Signed-off-by: Dave Chinner Reviewed-by: Darrick J. Wong --- fs/xfs/xfs_buf.c | 126 ++++++++++++++++++++++++++++++++----------------------- 1 file changed, 74 insertions(+), 52 deletions(-) diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c index 592800c..2e35d34 100644 --- a/fs/xfs/xfs_buf.c +++ b/fs/xfs/xfs_buf.c @@ -347,65 +347,55 @@ xfs_buf_free( kmem_cache_free(xfs_buf_zone, bp); } -/* - * Allocates all the pages for buffer in question and builds it's page list. - */ -STATIC int -xfs_buf_allocate_memory( - struct xfs_buf *bp, - uint flags) +static int +xfs_buf_alloc_kmem( + struct xfs_buf *bp, + size_t size, + xfs_buf_flags_t flags) { - size_t size; - size_t nbytes, offset; - gfp_t gfp_mask = xb_to_gfp(flags); - unsigned short page_count, i; - xfs_off_t start, end; - int error; - xfs_km_flags_t kmflag_mask = 0; + int align_mask = xfs_buftarg_dma_alignment(bp->b_target); + xfs_km_flags_t kmflag_mask = KM_NOFS; - /* - * assure zeroed buffer for non-read cases. - */ - if (!(flags & XBF_READ)) { + /* Assure zeroed buffer for non-read cases. */ + if (!(flags & XBF_READ)) kmflag_mask |= KM_ZERO; - gfp_mask |= __GFP_ZERO; - } - /* - * for buffers that are contained within a single page, just allocate - * the memory from the heap - there's no need for the complexity of - * page arrays to keep allocation down to order 0. - */ - size = BBTOB(bp->b_length); - if (size < PAGE_SIZE) { - int align_mask = xfs_buftarg_dma_alignment(bp->b_target); - bp->b_addr = kmem_alloc_io(size, align_mask, - KM_NOFS | kmflag_mask); - if (!bp->b_addr) { - /* low memory - use alloc_page loop instead */ - goto use_alloc_page; - } + bp->b_addr = kmem_alloc_io(size, align_mask, kmflag_mask); + if (!bp->b_addr) + return -ENOMEM; - if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) != - ((unsigned long)bp->b_addr & PAGE_MASK)) { - /* b_addr spans two pages - use alloc_page instead */ - kmem_free(bp->b_addr); - bp->b_addr = NULL; - goto use_alloc_page; - } - bp->b_offset = offset_in_page(bp->b_addr); - bp->b_pages = bp->b_page_array; - bp->b_pages[0] = kmem_to_page(bp->b_addr); - bp->b_page_count = 1; - bp->b_flags |= _XBF_KMEM; - return 0; + if (((unsigned long)(bp->b_addr + size - 1) & PAGE_MASK) != + ((unsigned long)bp->b_addr & PAGE_MASK)) { + /* b_addr spans two pages - use alloc_page instead */ + kmem_free(bp->b_addr); + bp->b_addr = NULL; + return -ENOMEM; } + bp->b_offset = offset_in_page(bp->b_addr); + bp->b_pages = bp->b_page_array; + bp->b_pages[0] = kmem_to_page(bp->b_addr); + bp->b_page_count = 1; + bp->b_flags |= _XBF_KMEM; + return 0; +} + +static int +xfs_buf_alloc_pages( + struct xfs_buf *bp, + uint page_count, + xfs_buf_flags_t flags) +{ + gfp_t gfp_mask = xb_to_gfp(flags); + size_t size; + size_t offset; + size_t nbytes; + int i; + int error; + + /* Assure zeroed buffer for non-read cases. */ + if (!(flags & XBF_READ)) + gfp_mask |= __GFP_ZERO; -use_alloc_page: - start = BBTOB(bp->b_maps[0].bm_bn) >> PAGE_SHIFT; - end = (BBTOB(bp->b_maps[0].bm_bn + bp->b_length) + PAGE_SIZE - 1) - >> PAGE_SHIFT; - page_count = end - start; error = _xfs_buf_get_pages(bp, page_count); if (unlikely(error)) return error; @@ -458,6 +448,38 @@ out_free_pages: return error; } + +/* + * Allocates all the pages for buffer in question and builds it's page list. + */ +static int +xfs_buf_allocate_memory( + struct xfs_buf *bp, + uint flags) +{ + size_t size; + xfs_off_t start, end; + int error; + + /* + * For buffers that fit entirely within a single page, first attempt to + * allocate the memory from the heap to minimise memory usage. If we + * can't get heap memory for these small buffers, we fall back to using + * the page allocator. + */ + size = BBTOB(bp->b_length); + if (size < PAGE_SIZE) { + error = xfs_buf_alloc_kmem(bp, size, flags); + if (!error) + return 0; + } + + start = BBTOB(bp->b_maps[0].bm_bn) >> PAGE_SHIFT; + end = (BBTOB(bp->b_maps[0].bm_bn + bp->b_length) + PAGE_SIZE - 1) + >> PAGE_SHIFT; + return xfs_buf_alloc_pages(bp, end - start, flags); +} + /* * Map buffer into kernel address-space if necessary. */ -- 2.7.4