| From: Miklos Szeredi <mszeredi@redhat.com> |
| Date: Thu, 8 Feb 2018 15:17:38 +0100 |
| Subject: fuse: atomic_o_trunc should truncate pagecache |
| |
| commit df0e91d488276086bc07da2e389986cae0048c37 upstream. |
| |
| Fuse has an "atomic_o_trunc" mode, where userspace filesystem uses the |
| O_TRUNC flag in the OPEN request to truncate the file atomically with the |
| open. |
| |
| In this mode there's no need to send a SETATTR request to userspace after |
| the open, so fuse_do_setattr() checks this mode and returns. But this |
| misses the important step of truncating the pagecache. |
| |
| Add the missing parts of truncation to the ATTR_OPEN branch. |
| |
| Reported-by: Chad Austin <chadaustin@fb.com> |
| Fixes: 6ff958edbf39 ("fuse: add atomic open+truncate support") |
| Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> |
| Signed-off-by: Ben Hutchings <ben@decadent.org.uk> |
| --- |
| fs/fuse/dir.c | 13 ++++++++++++- |
| 1 file changed, 12 insertions(+), 1 deletion(-) |
| |
| --- a/fs/fuse/dir.c |
| +++ b/fs/fuse/dir.c |
| @@ -1728,8 +1728,19 @@ int fuse_do_setattr(struct dentry *dentr |
| return err; |
| |
| if (attr->ia_valid & ATTR_OPEN) { |
| - if (fc->atomic_o_trunc) |
| + /* This is coming from open(..., ... | O_TRUNC); */ |
| + WARN_ON(!(attr->ia_valid & ATTR_SIZE)); |
| + WARN_ON(attr->ia_size != 0); |
| + if (fc->atomic_o_trunc) { |
| + /* |
| + * No need to send request to userspace, since actual |
| + * truncation has already been done by OPEN. But still |
| + * need to truncate page cache. |
| + */ |
| + i_size_write(inode, 0); |
| + truncate_pagecache(inode, 0); |
| return 0; |
| + } |
| file = NULL; |
| } |
| |
