projects / thirdparty / kernel / stable-queue.git / blame
| Commit | Line | Data |
|---|---|---|
| c430f7d2 GKH |
1 | From 0ab08f576b9e6a6b689fc6b4e632079b978e619b Mon Sep 17 00:00:00 2001 |
| 2 | From: Maxim Patlasov <MPatlasov@parallels.com> | |
| 3 | Date: Fri, 13 Sep 2013 19:20:16 +0400 | |
| 4 | Subject: fuse: fix fallocate vs. ftruncate race | |
| 5 | ||
| 6 | From: Maxim Patlasov <MPatlasov@parallels.com> | |
| 7 | ||
| 8 | commit 0ab08f576b9e6a6b689fc6b4e632079b978e619b upstream. | |
| 9 | ||
| 10 | A former patch introducing FUSE_I_SIZE_UNSTABLE flag provided detailed | |
| 11 | description of races between ftruncate and anyone who can extend i_size: | |
| 12 | ||
| 13 | > 1. As in the previous scenario fuse_dentry_revalidate() discovered that i_size | |
| 14 | > changed (due to our own fuse_do_setattr()) and is going to call | |
| 15 | > truncate_pagecache() for some 'new_size' it believes valid right now. But by | |
| 16 | > the time that particular truncate_pagecache() is called ... | |
| 17 | > 2. fuse_do_setattr() returns (either having called truncate_pagecache() or | |
| 18 | > not -- it doesn't matter). | |
| 19 | > 3. The file is extended either by write(2) or ftruncate(2) or fallocate(2). | |
| 20 | > 4. mmap-ed write makes a page in the extended region dirty. | |
| 21 | ||
| 22 | This patch adds necessary bits to fuse_file_fallocate() to protect from that | |
| 23 | race. | |
| 24 | ||
| 25 | Signed-off-by: Maxim Patlasov <mpatlasov@parallels.com> | |
| 26 | Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> | |
| 27 | Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> | |
| 28 | ||
| 29 | --- | |
| 30 | fs/fuse/file.c | 7 +++++++ | |
| 31 | 1 file changed, 7 insertions(+) | |
| 32 | ||
| 33 | --- a/fs/fuse/file.c | |
| 34 | +++ b/fs/fuse/file.c | |
| 35 | @@ -2468,6 +2468,7 @@ static long fuse_file_fallocate(struct f | |
| 36 | { | |
| 37 | struct fuse_file *ff = file->private_data; | |
| 38 | struct inode *inode = file->f_inode; | |
| 39 | + struct fuse_inode *fi = get_fuse_inode(inode); | |
| 40 | struct fuse_conn *fc = ff->fc; | |
| 41 | struct fuse_req *req; | |
| 42 | struct fuse_fallocate_in inarg = { | |
| 43 | @@ -2496,6 +2497,9 @@ static long fuse_file_fallocate(struct f | |
| 44 | } | |
| 45 | } | |
| 46 | ||
| 47 | + if (!(mode & FALLOC_FL_KEEP_SIZE)) | |
| 48 | + set_bit(FUSE_I_SIZE_UNSTABLE, &fi->state); | |
| 49 | + | |
| 50 | req = fuse_get_req_nopages(fc); | |
| 51 | if (IS_ERR(req)) { | |
| 52 | err = PTR_ERR(req); | |
| 53 | @@ -2528,6 +2532,9 @@ static long fuse_file_fallocate(struct f | |
| 54 | fuse_invalidate_attr(inode); | |
| 55 | ||
| 56 | out: | |
| 57 | + if (!(mode & FALLOC_FL_KEEP_SIZE)) | |
| 58 | + clear_bit(FUSE_I_SIZE_UNSTABLE, &fi->state); | |
| 59 | + | |
| 60 | if (lock_inode) | |
| 61 | mutex_unlock(&inode->i_mutex); | |
| 62 |