It turns out the slub allocator won't always give us aligned memory,
and on some controllers this can lead to data corruption. Remove the
special slab backed fast path in xfs_buf_allocate_memory. The only
downside of this is a slight waste of memory for metadata buffers
smaller than page size.
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
---
fs/xfs/xfs_buf.c | 37 ++++---------------------------------
fs/xfs/xfs_buf.h | 6 ++----
2 files changed, 6 insertions(+), 37 deletions(-)
diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
index e839907e8492..4808fd38e7d7 100644
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -313,8 +313,8 @@ xfs_buf_free(
__free_page(page);
}
- } else if (bp->b_flags & _XBF_KMEM)
- kmem_free(bp->b_addr);
+ }
+
_xfs_buf_free_pages(bp);
xfs_buf_free_maps(bp);
kmem_zone_free(xfs_buf_zone, bp);
@@ -328,42 +328,13 @@ xfs_buf_allocate_memory(
xfs_buf_t *bp,
uint flags)
{
- size_t size;
+ size_t size = BBTOB(bp->b_length);
size_t nbytes, offset;
gfp_t gfp_mask = xb_to_gfp(flags);
unsigned short page_count, i;
xfs_off_t start, end;
int error;
- /*
- * 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) {
- bp->b_addr = kmem_alloc(size, KM_NOFS);
- 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] = virt_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;
@@ -628,7 +599,7 @@ xfs_buf_find(
if (bp->b_flags & XBF_STALE) {
ASSERT((bp->b_flags & _XBF_DELWRI_Q) == 0);
ASSERT(bp->b_iodone == NULL);
- bp->b_flags &= _XBF_KMEM | _XBF_PAGES;
+ bp->b_flags &= _XBF_PAGES;
bp->b_ops = NULL;
}
diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 4e3171acd0f8..338fabb91f61 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -47,9 +47,8 @@ typedef enum {
/* flags used only internally */
#define _XBF_PAGES (1 << 20)/* backed by refcounted pages */
-#define _XBF_KMEM (1 << 21)/* backed by heap memory */
-#define _XBF_DELWRI_Q (1 << 22)/* buffer on a delwri queue */
-#define _XBF_COMPOUND (1 << 23)/* compound buffer */
+#define _XBF_DELWRI_Q (1 << 21)/* buffer on a delwri queue */
+#define _XBF_COMPOUND (1 << 22)/* compound buffer */
typedef unsigned int xfs_buf_flags_t;
@@ -68,7 +67,6 @@ typedef unsigned int xfs_buf_flags_t;
{ XBF_TRYLOCK, "TRYLOCK" }, /* should never be set */\
{ XBF_UNMAPPED, "UNMAPPED" }, /* ditto */\
{ _XBF_PAGES, "PAGES" }, \
- { _XBF_KMEM, "KMEM" }, \
{ _XBF_DELWRI_Q, "DELWRI_Q" }, \
{ _XBF_COMPOUND, "COMPOUND" }
--
2.19.0
