diff options
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/fuse/file.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c index d365008fda44..336d1cf72da0 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -3337,6 +3337,24 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in, if (err) goto out; + /* + * Write out dirty pages in the destination file before sending the COPY + * request to userspace. After the request is completed, truncate off + * pages (including partial ones) from the cache that have been copied, + * since these contain stale data at that point. + * + * This should be mostly correct, but if the COPY writes to partial + * pages (at the start or end) and the parts not covered by the COPY are + * written through a memory map after calling fuse_writeback_range(), + * then these partial page modifications will be lost on truncation. + * + * It is unlikely that someone would rely on such mixed style + * modifications. Yet this does give less guarantees than if the + * copying was performed with write(2). + * + * To fix this a i_mmap_sem style lock could be used to prevent new + * faults while the copy is ongoing. + */ err = fuse_writeback_range(inode_out, pos_out, pos_out + len - 1); if (err) goto out; @@ -3360,6 +3378,10 @@ static ssize_t __fuse_copy_file_range(struct file *file_in, loff_t pos_in, if (err) goto out; + truncate_inode_pages_range(inode_out->i_mapping, + ALIGN_DOWN(pos_out, PAGE_SIZE), + ALIGN(pos_out + outarg.size, PAGE_SIZE) - 1); + if (fc->writeback_cache) { fuse_write_update_size(inode_out, pos_out + outarg.size); file_update_time(file_out); |