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authorOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>2006-01-08 01:02:13 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-08 20:13:47 -0800
commit05eb0b51fb46430050d5873458612f53e0234f2e (patch)
tree88b9398079f53f29dff7533fb27487ae725983b1 /fs/buffer.c
parent268fc16e343b4f8e249468747db2e658da46a814 (diff)
downloadblackbird-op-linux-05eb0b51fb46430050d5873458612f53e0234f2e.tar.gz
blackbird-op-linux-05eb0b51fb46430050d5873458612f53e0234f2e.zip
[PATCH] fat: support a truncate() for expanding size (generic_cont_expand)
This patch changes generic_cont_expand(), in order to share the code with fatfs. - Use vmtruncate() if ->prepare_write() returns a error. Even if ->prepare_write() returns an error, it may already have added some blocks. So, this truncates blocks outside of ->i_size by vmtruncate(). - Add generic_cont_expand_simple(). The generic_cont_expand_simple() assumes that ->prepare_write() can handle the block boundary. With this, we don't need to care the extra byte. And for expanding a file size by truncate(), fatfs uses the added generic_cont_expand_simple(). Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'fs/buffer.c')
-rw-r--r--fs/buffer.c60
1 files changed, 46 insertions, 14 deletions
diff --git a/fs/buffer.c b/fs/buffer.c
index 5287be18633b..55023231e460 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2160,11 +2160,12 @@ int block_read_full_page(struct page *page, get_block_t *get_block)
* truncates. Uses prepare/commit_write to allow the filesystem to
* deal with the hole.
*/
-int generic_cont_expand(struct inode *inode, loff_t size)
+static int __generic_cont_expand(struct inode *inode, loff_t size,
+ pgoff_t index, unsigned int offset)
{
struct address_space *mapping = inode->i_mapping;
struct page *page;
- unsigned long index, offset, limit;
+ unsigned long limit;
int err;
err = -EFBIG;
@@ -2176,24 +2177,24 @@ int generic_cont_expand(struct inode *inode, loff_t size)
if (size > inode->i_sb->s_maxbytes)
goto out;
- 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
- */
- if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) {
- offset++;
- }
- index = size >> PAGE_CACHE_SHIFT;
err = -ENOMEM;
page = grab_cache_page(mapping, index);
if (!page)
goto out;
err = mapping->a_ops->prepare_write(NULL, page, offset, offset);
- if (!err) {
- err = mapping->a_ops->commit_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);
+
unlock_page(page);
page_cache_release(page);
if (err > 0)
@@ -2202,6 +2203,36 @@ 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
+ */
+ if ((offset & (inode->i_sb->s_blocksize - 1)) == 0) {
+ /* caller must handle this extra byte. */
+ offset++;
+ }
+ index = size >> PAGE_CACHE_SHIFT;
+
+ return __generic_cont_expand(inode, size, index, offset);
+}
+
+int generic_cont_expand_simple(struct inode *inode, loff_t size)
+{
+ loff_t pos = size - 1;
+ pgoff_t index = pos >> PAGE_CACHE_SHIFT;
+ unsigned int offset = (pos & (PAGE_CACHE_SIZE - 1)) + 1;
+
+ /* prepare/commit_write can handle even if from==to==start of block. */
+ return __generic_cont_expand(inode, size, index, offset);
+}
+
/*
* For moronic filesystems that do not allow holes in file.
* We may have to extend the file.
@@ -3145,6 +3176,7 @@ EXPORT_SYMBOL(fsync_bdev);
EXPORT_SYMBOL(generic_block_bmap);
EXPORT_SYMBOL(generic_commit_write);
EXPORT_SYMBOL(generic_cont_expand);
+EXPORT_SYMBOL(generic_cont_expand_simple);
EXPORT_SYMBOL(init_buffer);
EXPORT_SYMBOL(invalidate_bdev);
EXPORT_SYMBOL(ll_rw_block);
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