fs: new cont helpers
Rework the generic block "cont" routines to handle the new aops. Supporting
cont_prepare_write would take quite a lot of code to support, so remove it
instead (and we later convert all filesystems to use it).
write_begin gets passed AOP_FLAG_CONT_EXPAND when called from
generic_cont_expand, so filesystems can avoid the old hacks they used.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/buffer.c b/fs/buffer.c
index 68b8fbd..1f15774 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2156,14 +2156,14 @@
}
/* utility function for filesystems that need to do work on expanding
- * truncates. Uses prepare/commit_write to allow the filesystem to
+ * truncates. Uses filesystem pagecache writes to allow the filesystem to
* deal with the hole.
*/
-static int __generic_cont_expand(struct inode *inode, loff_t size,
- pgoff_t index, unsigned int offset)
+int generic_cont_expand_simple(struct inode *inode, loff_t size)
{
struct address_space *mapping = inode->i_mapping;
struct page *page;
+ void *fsdata;
unsigned long limit;
int err;
@@ -2176,140 +2176,134 @@
if (size > inode->i_sb->s_maxbytes)
goto out;
- err = -ENOMEM;
- page = grab_cache_page(mapping, index);
- if (!page)
+ err = pagecache_write_begin(NULL, mapping, size, 0,
+ AOP_FLAG_UNINTERRUPTIBLE|AOP_FLAG_CONT_EXPAND,
+ &page, &fsdata);
+ if (err)
goto out;
- err = mapping->a_ops->prepare_write(NULL, page, offset, offset);
- if (err) {
- /*
- * ->prepare_write() may have instantiated a few blocks
- * outside i_size. Trim these off again.
- */
- unlock_page(page);
- page_cache_release(page);
- vmtruncate(inode, inode->i_size);
- goto out;
- }
- err = mapping->a_ops->commit_write(NULL, page, offset, offset);
+ err = pagecache_write_end(NULL, mapping, size, 0, 0, page, fsdata);
+ BUG_ON(err > 0);
- unlock_page(page);
- page_cache_release(page);
- if (err > 0)
- err = 0;
out:
return err;
}
int generic_cont_expand(struct inode *inode, loff_t size)
{
- pgoff_t index;
unsigned int offset;
offset = (size & (PAGE_CACHE_SIZE - 1)); /* Within page */
/* ugh. in prepare/commit_write, if from==to==start of block, we
- ** skip the prepare. make sure we never send an offset for the start
- ** of a block
- */
+ * skip the prepare. make sure we never send an offset for the start
+ * of a block.
+ * XXX: actually, this should be handled in those filesystems by
+ * checking for the AOP_FLAG_CONT_EXPAND flag.
+ */
if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) {
/* caller must handle this extra byte. */
- offset++;
+ size++;
}
- index = size >> PAGE_CACHE_SHIFT;
-
- return __generic_cont_expand(inode, size, index, offset);
+ return generic_cont_expand_simple(inode, size);
}
-int generic_cont_expand_simple(struct inode *inode, loff_t size)
+int cont_expand_zero(struct file *file, struct address_space *mapping,
+ loff_t pos, loff_t *bytes)
{
- loff_t pos = size - 1;
- pgoff_t index = pos >> PAGE_CACHE_SHIFT;
- unsigned int offset = (pos & (PAGE_CACHE_SIZE - 1)) + 1;
+ struct inode *inode = mapping->host;
+ unsigned blocksize = 1 << inode->i_blkbits;
+ struct page *page;
+ void *fsdata;
+ pgoff_t index, curidx;
+ loff_t curpos;
+ unsigned zerofrom, offset, len;
+ int err = 0;
- /* prepare/commit_write can handle even if from==to==start of block. */
- return __generic_cont_expand(inode, size, index, offset);
+ index = pos >> PAGE_CACHE_SHIFT;
+ offset = pos & ~PAGE_CACHE_MASK;
+
+ while (index > (curidx = (curpos = *bytes)>>PAGE_CACHE_SHIFT)) {
+ zerofrom = curpos & ~PAGE_CACHE_MASK;
+ if (zerofrom & (blocksize-1)) {
+ *bytes |= (blocksize-1);
+ (*bytes)++;
+ }
+ len = PAGE_CACHE_SIZE - zerofrom;
+
+ err = pagecache_write_begin(file, mapping, curpos, len,
+ AOP_FLAG_UNINTERRUPTIBLE,
+ &page, &fsdata);
+ if (err)
+ goto out;
+ zero_user_page(page, zerofrom, len, KM_USER0);
+ err = pagecache_write_end(file, mapping, curpos, len, len,
+ page, fsdata);
+ if (err < 0)
+ goto out;
+ BUG_ON(err != len);
+ err = 0;
+ }
+
+ /* page covers the boundary, find the boundary offset */
+ if (index == curidx) {
+ zerofrom = curpos & ~PAGE_CACHE_MASK;
+ /* if we will expand the thing last block will be filled */
+ if (offset <= zerofrom) {
+ goto out;
+ }
+ if (zerofrom & (blocksize-1)) {
+ *bytes |= (blocksize-1);
+ (*bytes)++;
+ }
+ len = offset - zerofrom;
+
+ err = pagecache_write_begin(file, mapping, curpos, len,
+ AOP_FLAG_UNINTERRUPTIBLE,
+ &page, &fsdata);
+ if (err)
+ goto out;
+ zero_user_page(page, zerofrom, len, KM_USER0);
+ err = pagecache_write_end(file, mapping, curpos, len, len,
+ page, fsdata);
+ if (err < 0)
+ goto out;
+ BUG_ON(err != len);
+ err = 0;
+ }
+out:
+ return err;
}
/*
* For moronic filesystems that do not allow holes in file.
* We may have to extend the file.
*/
-
-int cont_prepare_write(struct page *page, unsigned offset,
- unsigned to, get_block_t *get_block, loff_t *bytes)
+int cont_write_begin(struct file *file, struct address_space *mapping,
+ loff_t pos, unsigned len, unsigned flags,
+ struct page **pagep, void **fsdata,
+ get_block_t *get_block, loff_t *bytes)
{
- struct address_space *mapping = page->mapping;
struct inode *inode = mapping->host;
- struct page *new_page;
- pgoff_t pgpos;
- long status;
- unsigned zerofrom;
unsigned blocksize = 1 << inode->i_blkbits;
+ unsigned zerofrom;
+ int err;
- while(page->index > (pgpos = *bytes>>PAGE_CACHE_SHIFT)) {
- status = -ENOMEM;
- new_page = grab_cache_page(mapping, pgpos);
- if (!new_page)
- goto out;
- /* we might sleep */
- if (*bytes>>PAGE_CACHE_SHIFT != pgpos) {
- unlock_page(new_page);
- page_cache_release(new_page);
- continue;
- }
- zerofrom = *bytes & ~PAGE_CACHE_MASK;
- if (zerofrom & (blocksize-1)) {
- *bytes |= (blocksize-1);
- (*bytes)++;
- }
- status = __block_prepare_write(inode, new_page, zerofrom,
- PAGE_CACHE_SIZE, get_block);
- if (status)
- goto out_unmap;
- zero_user_page(new_page, zerofrom, PAGE_CACHE_SIZE - zerofrom,
- KM_USER0);
- generic_commit_write(NULL, new_page, zerofrom, PAGE_CACHE_SIZE);
- unlock_page(new_page);
- page_cache_release(new_page);
+ err = cont_expand_zero(file, mapping, pos, bytes);
+ if (err)
+ goto out;
+
+ zerofrom = *bytes & ~PAGE_CACHE_MASK;
+ if (pos+len > *bytes && zerofrom & (blocksize-1)) {
+ *bytes |= (blocksize-1);
+ (*bytes)++;
}
- if (page->index < pgpos) {
- /* completely inside the area */
- zerofrom = offset;
- } else {
- /* page covers the boundary, find the boundary offset */
- zerofrom = *bytes & ~PAGE_CACHE_MASK;
-
- /* if we will expand the thing last block will be filled */
- if (to > zerofrom && (zerofrom & (blocksize-1))) {
- *bytes |= (blocksize-1);
- (*bytes)++;
- }
-
- /* starting below the boundary? Nothing to zero out */
- if (offset <= zerofrom)
- zerofrom = offset;
- }
- status = __block_prepare_write(inode, page, zerofrom, to, get_block);
- if (status)
- goto out1;
- if (zerofrom < offset) {
- zero_user_page(page, zerofrom, offset - zerofrom, KM_USER0);
- __block_commit_write(inode, page, zerofrom, offset);
- }
- return 0;
-out1:
- ClearPageUptodate(page);
- return status;
-
-out_unmap:
- ClearPageUptodate(new_page);
- unlock_page(new_page);
- page_cache_release(new_page);
+ *pagep = NULL;
+ err = block_write_begin(file, mapping, pos, len,
+ flags, pagep, fsdata, get_block);
out:
- return status;
+ return err;
}
int block_prepare_write(struct page *page, unsigned from, unsigned to,
@@ -3191,7 +3185,7 @@
EXPORT_SYMBOL(block_sync_page);
EXPORT_SYMBOL(block_truncate_page);
EXPORT_SYMBOL(block_write_full_page);
-EXPORT_SYMBOL(cont_prepare_write);
+EXPORT_SYMBOL(cont_write_begin);
EXPORT_SYMBOL(end_buffer_read_sync);
EXPORT_SYMBOL(end_buffer_write_sync);
EXPORT_SYMBOL(file_fsync);