On 06/11/2013 06:59 AM, Maxim Patlasov wrote: > 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' performs ordinary buffered write(2) with a length big enough > to extend the file beyond "offset + length" of fallocate call. > 3. Process 'A' resumes execution of fuse_file_fallocate() and calls > fuse_write_update_size(inode, offset + length). But 'offset + length' was > obsoleted by write from previous step. >
Hi Maxim, Doesn't fuse_write_update_size() already handle this particular case by only ever extending the size? Brian > Signed-off-by: Maxim V. Patlasov <[email protected]> > --- > fs/fuse/file.c | 10 ++++++---- > 1 files changed, 6 insertions(+), 4 deletions(-) > > diff --git a/fs/fuse/file.c b/fs/fuse/file.c > index e570081..8dfbf7d 100644 > --- a/fs/fuse/file.c > +++ b/fs/fuse/file.c > @@ -2470,14 +2470,16 @@ 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); > + if (mode & FALLOC_FL_PUNCH_HOLE) > fuse_set_nowrite(inode); > - } > > req = fuse_get_req_nopages(fc); > if (IS_ERR(req)) { > @@ -2511,10 +2513,10 @@ static long fuse_file_fallocate(struct file *file, > int mode, loff_t offset, > fuse_invalidate_attr(inode); > > out: > - if (mode & FALLOC_FL_PUNCH_HOLE) { > + if (mode & FALLOC_FL_PUNCH_HOLE) > fuse_release_nowrite(inode); > + if (lock_inode) > mutex_unlock(&inode->i_mutex); > - } > > return err; > } > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
