The approach is straight-forward: for compound pages we read out whole
huge page.
For huge page we cannot have array of buffer head pointers on stack --
it's 4096 pointers on x86-64 -- 'arr' is allocated with kmalloc() for
huge pages.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
fs/buffer.c | 22 +++++++++++++++++-----
include/linux/buffer_head.h | 9 +++++----
include/linux/page-flags.h | 2 +-
3 files changed, 23 insertions(+), 10 deletions(-)
diff --git a/fs/buffer.c b/fs/buffer.c
index 193ef03401ed..9ca197a924eb 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -870,7 +870,7 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
try_again:
head = NULL;
- offset = PAGE_SIZE;
+ offset = hpage_size(page);
while ((offset -= size) >= 0) {
bh = alloc_buffer_head(GFP_NOFS);
if (!bh)
@@ -1466,7 +1466,7 @@ void set_bh_page(struct buffer_head *bh,
struct page *page, unsigned long offset)
{
bh->b_page = page;
- BUG_ON(offset >= PAGE_SIZE);
+ BUG_ON(offset >= hpage_size(page));
if (PageHighMem(page))
/*
* This catches illegal uses and preserves the offset:
@@ -2239,11 +2239,13 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
{
struct inode *inode = page->mapping->host;
sector_t iblock, lblock;
- struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
+ struct buffer_head *arr_on_stack[MAX_BUF_PER_PAGE];
+ struct buffer_head *bh, *head, **arr = arr_on_stack;
unsigned int blocksize, bbits;
int nr, i;
int fully_mapped = 1;
+ VM_BUG_ON_PAGE(PageTail(page), page);
head = create_page_buffers(page, inode, 0);
blocksize = head->b_size;
bbits = block_size_bits(blocksize);
@@ -2254,6 +2256,11 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
nr = 0;
i = 0;
+ if (PageTransHuge(page)) {
+ arr = kmalloc(sizeof(struct buffer_head *) * HPAGE_PMD_NR *
+ MAX_BUF_PER_PAGE, GFP_NOFS);
+ }
+
do {
if (buffer_uptodate(bh))
continue;
@@ -2269,7 +2276,9 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
SetPageError(page);
}
if (!buffer_mapped(bh)) {
- zero_user(page, i * blocksize, blocksize);
+ zero_user(page + (i * blocksize / PAGE_SIZE),
+ i * blocksize % PAGE_SIZE,
+ blocksize);
if (!err)
set_buffer_uptodate(bh);
continue;
@@ -2295,7 +2304,7 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
if (!PageError(page))
SetPageUptodate(page);
unlock_page(page);
- return 0;
+ goto out;
}
/* Stage two: lock the buffers */
@@ -2317,6 +2326,9 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
else
submit_bh(REQ_OP_READ, 0, bh);
}
+out:
+ if (arr != arr_on_stack)
+ kfree(arr);
return 0;
}
EXPORT_SYMBOL(block_read_full_page);
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index ebbacd14d450..2389e8fd6127 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -131,13 +131,14 @@ BUFFER_FNS(Meta, meta)
BUFFER_FNS(Prio, prio)
BUFFER_FNS(Defer_Completion, defer_completion)
-#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK)
+#define bh_offset(bh) ((unsigned long)(bh)->b_data & ~hpage_mask(bh->b_page))
/* If we *know* page->private refers to buffer_heads */
-#define page_buffers(page) \
+#define page_buffers(__page) \
({ \
- BUG_ON(!PagePrivate(page)); \
- ((struct buffer_head *)page_private(page)); \
+ struct page *p = compound_head(__page); \
+ BUG_ON(!PagePrivate(p)); \
+ ((struct buffer_head *)page_private(p)); \
})
#define page_has_buffers(page) PagePrivate(page)
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index de90abb7c84e..89f0e9f26694 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -730,7 +730,7 @@ static inline void ClearPageSlabPfmemalloc(struct page *page)
*/
static inline int page_has_private(struct page *page)
{
- return !!(page->flags & PAGE_FLAGS_PRIVATE);
+ return !!(compound_head(page)->flags & PAGE_FLAGS_PRIVATE);
}
#undef PF_ANY
--
2.8.1
--
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