diff options
Diffstat (limited to 'fs/dax.c')
| -rw-r--r-- | fs/dax.c | 38 |
1 files changed, 32 insertions, 6 deletions
@@ -464,31 +464,35 @@ int dax_fault(struct vm_area_struct *vma, struct vm_fault *vmf, EXPORT_SYMBOL_GPL(dax_fault); /** - * dax_truncate_page - handle a partial page being truncated in a DAX file + * dax_zero_page_range - zero a range within a page of a DAX file * @inode: The file being truncated * @from: The file offset that is being truncated to + * @length: The number of bytes to zero * @get_block: The filesystem method used to translate file offsets to blocks * - * Similar to block_truncate_page(), this function can be called by a - * filesystem when it is truncating an DAX file to handle the partial page. + * This function can be called by a filesystem when it is zeroing part of a + * page in a DAX file. This is intended for hole-punch operations. If + * you are truncating a file, the helper function dax_truncate_page() may be + * more convenient. * * We work in terms of PAGE_CACHE_SIZE here for commonality with * block_truncate_page(), but we could go down to PAGE_SIZE if the filesystem * took care of disposing of the unnecessary blocks. Even if the filesystem * block size is smaller than PAGE_SIZE, we have to zero the rest of the page - * since the file might be mmaped. + * since the file might be mmapped. */ -int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block) +int dax_zero_page_range(struct inode *inode, loff_t from, unsigned length, + get_block_t get_block) { struct buffer_head bh; pgoff_t index = from >> PAGE_CACHE_SHIFT; unsigned offset = from & (PAGE_CACHE_SIZE-1); - unsigned length = PAGE_CACHE_ALIGN(from) - from; int err; /* Block boundary? Nothing to do */ if (!length) return 0; + BUG_ON((offset + length) > PAGE_CACHE_SIZE); memset(&bh, 0, sizeof(bh)); bh.b_size = PAGE_CACHE_SIZE; @@ -505,4 +509,26 @@ int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block) return 0; } +EXPORT_SYMBOL_GPL(dax_zero_page_range); + +/** + * dax_truncate_page - handle a partial page being truncated in a DAX file + * @inode: The file being truncated + * @from: The file offset that is being truncated to + * @get_block: The filesystem method used to translate file offsets to blocks + * + * Similar to block_truncate_page(), this function can be called by a + * filesystem when it is truncating a DAX file to handle the partial page. + * + * We work in terms of PAGE_CACHE_SIZE here for commonality with + * block_truncate_page(), but we could go down to PAGE_SIZE if the filesystem + * took care of disposing of the unnecessary blocks. Even if the filesystem + * block size is smaller than PAGE_SIZE, we have to zero the rest of the page + * since the file might be mmapped. + */ +int dax_truncate_page(struct inode *inode, loff_t from, get_block_t get_block) +{ + unsigned length = PAGE_CACHE_ALIGN(from) - from; + return dax_zero_page_range(inode, from, length, get_block); +} EXPORT_SYMBOL_GPL(dax_truncate_page); |