diff options
| author | Maxim Patlasov <MPatlasov@parallels.com> | 2013-06-13 12:16:39 +0400 |
|---|---|---|
| committer | TARKZiM <tom8476oo@gmail.com> | 2021-08-25 14:54:59 +0800 |
| commit | 997d324a22c9ba83af4e952fee3f0374f7bd5b68 (patch) | |
| tree | 04810f2c4d0692536ccf3fd06e354eb5abcba7aa | |
| parent | beb163ac53e47b922c145c9ab1bc5c60e98f5174 (diff) | |
fuse: hold i_mutex in fuse_file_fallocate()
Changing size of a file on server and local update (fuse_write_update_size)
should be always protected by inode->i_mutex. Otherwise a race like this is
possible:
1. Process 'A' calls fallocate(2) to extend file (~FALLOC_FL_KEEP_SIZE).
fuse_file_fallocate() sends FUSE_FALLOCATE request to the server.
2. Process 'B' calls ftruncate(2) shrinking the file. fuse_do_setattr()
sends shrinking FUSE_SETATTR request to the server and updates local i_size
by i_size_write(inode, outarg.attr.size).
3. Process 'A' resumes execution of fuse_file_fallocate() and calls
fuse_write_update_size(inode, offset + length). But 'offset + length' was
obsoleted by ftruncate from previous step.
Changed in v2 (thanks Brian and Anand for suggestions):
- made relation between mutex_lock() and fuse_set_nowrite(inode) more
explicit and clear.
- updated patch description to use ftruncate(2) in example
Signed-off-by: Maxim V. Patlasov <MPatlasov@parallels.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Change-Id: I9dfd90c492fedae571afa30f26b319cb8e1aad14
| -rw-r--r-- | fs/fuse/file.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c index 3e4bc2d5407..1b1c6857247 100644 --- a/fs/fuse/file.c +++ b/fs/fuse/file.c @@ -2509,13 +2509,16 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset, .mode = mode }; int err; + bool lock_inode = !(mode & FALLOC_FL_KEEP_SIZE) || + (mode & FALLOC_FL_PUNCH_HOLE); if (fc->no_fallocate) return -EOPNOTSUPP; - if (mode & FALLOC_FL_PUNCH_HOLE) { + if (lock_inode) { mutex_lock(&inode->i_mutex); - fuse_set_nowrite(inode); + if (mode & FALLOC_FL_PUNCH_HOLE) + fuse_set_nowrite(inode); } req = fuse_get_req_nopages(fc); @@ -2550,8 +2553,9 @@ static long fuse_file_fallocate(struct file *file, int mode, loff_t offset, fuse_invalidate_attr(inode); out: - if (mode & FALLOC_FL_PUNCH_HOLE) { - fuse_release_nowrite(inode); + if (lock_inode) { + if (mode & FALLOC_FL_PUNCH_HOLE) + fuse_release_nowrite(inode); mutex_unlock(&inode->i_mutex); } |