From: OGAWA Hirofumi 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 Signed-off-by: Andrew Morton --- fs/buffer.c | 60 +++++++++++++++++++++++++++++++++----------- fs/fat/file.c | 31 ++++++++++++++++++++-- include/linux/buffer_head.h | 3 +- 3 files changed, 76 insertions(+), 18 deletions(-) diff -puN fs/buffer.c~fat-support-a-truncate-for-expanding-size-2 fs/buffer.c --- devel/fs/buffer.c~fat-support-a-truncate-for-expanding-size-2 2005-11-09 20:02:20.000000000 -0800 +++ devel-akpm/fs/buffer.c 2005-11-09 20:02:20.000000000 -0800 @@ -2162,11 +2162,12 @@ int block_read_full_page(struct page *pa * 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; @@ -2178,24 +2179,24 @@ int generic_cont_expand(struct inode *in 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) @@ -2204,6 +2205,36 @@ 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. @@ -3147,6 +3178,7 @@ 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); diff -puN fs/fat/file.c~fat-support-a-truncate-for-expanding-size-2 fs/fat/file.c --- devel/fs/fat/file.c~fat-support-a-truncate-for-expanding-size-2 2005-11-09 20:02:20.000000000 -0800 +++ devel-akpm/fs/fat/file.c 2005-11-09 20:02:20.000000000 -0800 @@ -11,6 +11,7 @@ #include #include #include +#include int fat_generic_ioctl(struct inode *inode, struct file *filp, unsigned int cmd, unsigned long arg) @@ -124,6 +125,24 @@ struct file_operations fat_file_operatio .sendfile = generic_file_sendfile, }; +static int fat_cont_expand(struct inode *inode, loff_t size) +{ + struct address_space *mapping = inode->i_mapping; + loff_t start = inode->i_size, count = size - inode->i_size; + int err; + + err = generic_cont_expand_simple(inode, size); + if (err) + goto out; + + inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC; + mark_inode_dirty(inode); + if (IS_SYNC(inode)) + err = sync_page_range_nolock(inode, mapping, start, count); +out: + return err; +} + int fat_notify_change(struct dentry *dentry, struct iattr *attr) { struct msdos_sb_info *sbi = MSDOS_SB(dentry->d_sb); @@ -132,11 +151,17 @@ int fat_notify_change(struct dentry *den lock_kernel(); - /* FAT cannot truncate to a longer file */ + /* + * Expand the file. Since inode_setattr() updates ->i_size + * before calling the ->truncate(), but FAT needs to fill the + * hole before it. + */ if (attr->ia_valid & ATTR_SIZE) { if (attr->ia_size > inode->i_size) { - error = -EPERM; - goto out; + error = fat_cont_expand(inode, attr->ia_size); + if (error || attr->ia_valid == ATTR_SIZE) + goto out; + attr->ia_valid &= ~ATTR_SIZE; } } diff -puN include/linux/buffer_head.h~fat-support-a-truncate-for-expanding-size-2 include/linux/buffer_head.h --- devel/include/linux/buffer_head.h~fat-support-a-truncate-for-expanding-size-2 2005-11-09 20:02:20.000000000 -0800 +++ devel-akpm/include/linux/buffer_head.h 2005-11-09 20:02:20.000000000 -0800 @@ -197,7 +197,8 @@ int block_read_full_page(struct page*, g int block_prepare_write(struct page*, unsigned, unsigned, get_block_t*); int cont_prepare_write(struct page*, unsigned, unsigned, get_block_t*, loff_t *); -int generic_cont_expand(struct inode *inode, loff_t size) ; +int generic_cont_expand(struct inode *inode, loff_t size); +int generic_cont_expand_simple(struct inode *inode, loff_t size); int block_commit_write(struct page *page, unsigned from, unsigned to); int block_sync_page(struct page *); sector_t generic_block_bmap(struct address_space *, sector_t, get_block_t *); _