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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 <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
This commit is contained in:
Dave Chinner 2021-06-01 13:40:02 +10:00 committed by Dave Chinner
parent d07f6ca923
commit 0a683794ac
1 changed files with 76 additions and 54 deletions
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130
fs/xfs/xfs_buf.c
View File

@ -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;
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;
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;
}
/*
* 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;
}
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;
}
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.
*/