From: viro@parcelfarce.linux.theplanet.co.uk
Patch switches cramfs_read() to direct use of pagecache and
eliminates all messing with buffer_heads. Fixes the interaction with
ramdisk (there set_blocksize() simply killed the ramdisk contents) and
gets code less brittle overall.
fs/cramfs/inode.c | 50 ++++++++++++++++++++++++++------------------------
1 files changed, 26 insertions(+), 24 deletions(-)
diff -puN fs/cramfs/inode.c~cramfs-use-pagecache fs/cramfs/inode.c
--- 25/fs/cramfs/inode.c~cramfs-use-pagecache 2003-11-10 19:36:04.000000000 -0800
+++ 25-akpm/fs/cramfs/inode.c 2003-11-10 19:36:04.000000000 -0800
@@ -112,8 +112,8 @@ static int next_buffer;
*/
static void *cramfs_read(struct super_block *sb, unsigned int offset, unsigned int len)
{
- struct buffer_head * bh_array[BLKS_PER_BUF];
- struct buffer_head * read_array[BLKS_PER_BUF];
+ struct address_space *mapping = sb->s_bdev->bd_inode->i_mapping;
+ struct page *pages[BLKS_PER_BUF];
unsigned i, blocknr, buffer, unread;
unsigned long devsize;
char *data;
@@ -138,33 +138,36 @@ static void *cramfs_read(struct super_bl
return read_buffers[i] + blk_offset;
}
- devsize = sb->s_bdev->bd_inode->i_size >> 12;
- if (!devsize)
- devsize = ~0UL;
+ devsize = mapping->host->i_size >> PAGE_CACHE_SHIFT;
/* Ok, read in BLKS_PER_BUF pages completely first. */
unread = 0;
for (i = 0; i < BLKS_PER_BUF; i++) {
- struct buffer_head *bh;
+ struct page *page = NULL;
- bh = NULL;
if (blocknr + i < devsize) {
- bh = sb_getblk(sb, blocknr + i);
- if (!buffer_uptodate(bh))
- read_array[unread++] = bh;
+ page = read_cache_page(mapping, blocknr + i,
+ (filler_t *)mapping->a_ops->readpage,
+ NULL);
+ /* synchronous error? */
+ if (IS_ERR(page))
+ page = NULL;
}
- bh_array[i] = bh;
+ pages[i] = page;
}
- if (unread) {
- ll_rw_block(READ, unread, read_array);
- do {
- unread--;
- wait_on_buffer(read_array[unread]);
- } while (unread);
+ for (i = 0; i < BLKS_PER_BUF; i++) {
+ struct page *page = pages[i];
+ if (page) {
+ wait_on_page_locked(page);
+ if (!PageUptodate(page)) {
+ /* asynchronous error */
+ page_cache_release(page);
+ pages[i] = NULL;
+ }
+ }
}
- /* Ok, copy them to the staging area without sleeping. */
buffer = next_buffer;
next_buffer = NEXT_BUFFER(buffer);
buffer_blocknr[buffer] = blocknr;
@@ -172,10 +175,11 @@ static void *cramfs_read(struct super_bl
data = read_buffers[buffer];
for (i = 0; i < BLKS_PER_BUF; i++) {
- struct buffer_head * bh = bh_array[i];
- if (bh) {
- memcpy(data, bh->b_data, PAGE_CACHE_SIZE);
- brelse(bh);
+ struct page *page = pages[i];
+ if (page) {
+ memcpy(data, kmap(page), PAGE_CACHE_SIZE);
+ kunmap(page);
+ page_cache_release(page);
} else
memset(data, 0, PAGE_CACHE_SIZE);
data += PAGE_CACHE_SIZE;
@@ -202,8 +206,6 @@ static int cramfs_fill_super(struct supe
sb->s_fs_info = sbi;
memset(sbi, 0, sizeof(struct cramfs_sb_info));
- sb_set_blocksize(sb, PAGE_CACHE_SIZE);
-
/* Invalidate the read buffers on mount: think disk change.. */
down(&read_mutex);
for (i = 0; i < READ_BUFFERS; i++)
_