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-rw-r--r--fs/buffer.c66
1 files changed, 30 insertions, 36 deletions
diff --git a/fs/buffer.c b/fs/buffer.c
index 9f6d2e4..58e2e7b 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -914,7 +914,7 @@ link_dev_buffers(struct page *page, struct buffer_head *head)
/*
* Initialise the state of a blockdev page's buffers.
*/
-static void
+static sector_t
init_page_buffers(struct page *page, struct block_device *bdev,
sector_t block, int size)
{
@@ -936,33 +936,41 @@ init_page_buffers(struct page *page, struct block_device *bdev,
block++;
bh = bh->b_this_page;
} while (bh != head);
+
+ /*
+ * Caller needs to validate requested block against end of device.
+ */
+ return end_block;
}
/*
* Create the page-cache page that contains the requested block.
*
- * This is user purely for blockdev mappings.
+ * This is used purely for blockdev mappings.
*/
-static struct page *
+static int
grow_dev_page(struct block_device *bdev, sector_t block,
- pgoff_t index, int size)
+ pgoff_t index, int size, int sizebits)
{
struct inode *inode = bdev->bd_inode;
struct page *page;
struct buffer_head *bh;
+ sector_t end_block;
+ int ret = 0; /* Will call free_more_memory() */
page = find_or_create_page(inode->i_mapping, index,
(mapping_gfp_mask(inode->i_mapping) & ~__GFP_FS)|__GFP_MOVABLE);
if (!page)
- return NULL;
+ return ret;
BUG_ON(!PageLocked(page));
if (page_has_buffers(page)) {
bh = page_buffers(page);
if (bh->b_size == size) {
- init_page_buffers(page, bdev, block, size);
- return page;
+ end_block = init_page_buffers(page, bdev,
+ index << sizebits, size);
+ goto done;
}
if (!try_to_free_buffers(page))
goto failed;
@@ -982,14 +990,14 @@ grow_dev_page(struct block_device *bdev, sector_t block,
*/
spin_lock(&inode->i_mapping->private_lock);
link_dev_buffers(page, bh);
- init_page_buffers(page, bdev, block, size);
+ end_block = init_page_buffers(page, bdev, index << sizebits, size);
spin_unlock(&inode->i_mapping->private_lock);
- return page;
-
+done:
+ ret = (block < end_block) ? 1 : -ENXIO;
failed:
unlock_page(page);
page_cache_release(page);
- return NULL;
+ return ret;
}
/*
@@ -999,7 +1007,6 @@ failed:
static int
grow_buffers(struct block_device *bdev, sector_t block, int size)
{
- struct page *page;
pgoff_t index;
int sizebits;
@@ -1023,22 +1030,14 @@ grow_buffers(struct block_device *bdev, sector_t block, int size)
bdevname(bdev, b));
return -EIO;
}
- block = index << sizebits;
+
/* Create a page with the proper size buffers.. */
- page = grow_dev_page(bdev, block, index, size);
- if (!page)
- return 0;
- unlock_page(page);
- page_cache_release(page);
- return 1;
+ return grow_dev_page(bdev, block, index, size, sizebits);
}
static struct buffer_head *
__getblk_slow(struct block_device *bdev, sector_t block, int size)
{
- int ret;
- struct buffer_head *bh;
-
/* Size must be multiple of hard sectorsize */
if (unlikely(size & (bdev_logical_block_size(bdev)-1) ||
(size < 512 || size > PAGE_SIZE))) {
@@ -1051,21 +1050,20 @@ __getblk_slow(struct block_device *bdev, sector_t block, int size)
return NULL;
}
-retry:
- bh = __find_get_block(bdev, block, size);
- if (bh)
- return bh;
+ for (;;) {
+ struct buffer_head *bh;
+ int ret;
- ret = grow_buffers(bdev, block, size);
- if (ret == 0) {
- free_more_memory();
- goto retry;
- } else if (ret > 0) {
bh = __find_get_block(bdev, block, size);
if (bh)
return bh;
+
+ ret = grow_buffers(bdev, block, size);
+ if (ret < 0)
+ return NULL;
+ if (ret == 0)
+ free_more_memory();
}
- return NULL;
}
/*
@@ -1321,10 +1319,6 @@ EXPORT_SYMBOL(__find_get_block);
* which corresponds to the passed block_device, block and size. The
* returned buffer has its reference count incremented.
*
- * __getblk() cannot fail - it just keeps trying. If you pass it an
- * illegal block number, __getblk() will happily return a buffer_head
- * which represents the non-existent block. Very weird.
- *
* __getblk() will lock up the machine if grow_dev_page's try_to_free_buffers()
* attempt is failing. FIXME, perhaps?
*/
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