diff options
| -rw-r--r-- | fs/iomap/buffered-io.c | 18 | ||||
| -rw-r--r-- | include/linux/pagemap.h | 28 |
2 files changed, 33 insertions, 13 deletions
diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index 828444e14d09..7c84c4c027c4 100644 --- a/fs/iomap/buffered-io.c +++ b/fs/iomap/buffered-io.c @@ -1077,24 +1077,16 @@ vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops) struct page *page = vmf->page; struct inode *inode = file_inode(vmf->vma->vm_file); unsigned long length; - loff_t offset, size; + loff_t offset; ssize_t ret; lock_page(page); - size = i_size_read(inode); - offset = page_offset(page); - if (page->mapping != inode->i_mapping || offset > size) { - /* We overload EFAULT to mean page got truncated */ - ret = -EFAULT; + ret = page_mkwrite_check_truncate(page, inode); + if (ret < 0) goto out_unlock; - } - - /* page is wholly or partially inside EOF */ - if (offset > size - PAGE_SIZE) - length = offset_in_page(size); - else - length = PAGE_SIZE; + length = ret; + offset = page_offset(page); while (length > 0) { ret = iomap_apply(inode, offset, length, IOMAP_WRITE | IOMAP_FAULT, ops, page, diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 37a4d9e32cd3..ccb14b6a16b5 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -636,4 +636,32 @@ static inline unsigned long dir_pages(struct inode *inode) PAGE_SHIFT; } +/** + * page_mkwrite_check_truncate - check if page was truncated + * @page: the page to check + * @inode: the inode to check the page against + * + * Returns the number of bytes in the page up to EOF, + * or -EFAULT if the page was truncated. + */ +static inline int page_mkwrite_check_truncate(struct page *page, + struct inode *inode) +{ + loff_t size = i_size_read(inode); + pgoff_t index = size >> PAGE_SHIFT; + int offset = offset_in_page(size); + + if (page->mapping != inode->i_mapping) + return -EFAULT; + + /* page is wholly inside EOF */ + if (page->index < index) + return PAGE_SIZE; + /* page is wholly past EOF */ + if (page->index > index || !offset) + return -EFAULT; + /* page is partially inside EOF */ + return offset; +} + #endif /* _LINUX_PAGEMAP_H */ |