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fuse: atomic_o_trunc should truncate pagecache

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commit df0e91d488 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: 6ff958edbf ("fuse: add atomic open+truncate support")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Miklos Szeredi 2018-02-08 15:17:38 +01:00 committed by Greg Kroah-Hartman
parent 02832578eb
commit 2f7bf369b5
1 changed files with 12 additions and 1 deletions
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13
fs/fuse/dir.c
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@ -1629,8 +1629,19 @@ int fuse_do_setattr(struct dentry *dentry, struct iattr *attr,
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;
}