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author | OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> | 2006-01-08 01:02:13 -0800 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-01-08 20:13:47 -0800 |
commit | 05eb0b51fb46430050d5873458612f53e0234f2e (patch) | |
tree | 88b9398079f53f29dff7533fb27487ae725983b1 /fs/buffer.c | |
parent | 268fc16e343b4f8e249468747db2e658da46a814 (diff) | |
download | blackbird-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.c | 60 |
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); |