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authorMiklos Szeredi <mszeredi@suse.cz>2011-08-08 16:08:08 +0200
committerMiklos Szeredi <mszeredi@suse.cz>2011-08-08 16:08:08 +0200
commit37fb3a30b46237f23cfdf7ee09d49f9888dd13bf (patch)
treec36910e300ade812159d12218fdf122b3d2ef3de /fs/fuse
parenta2daff6803a384ce065e3681a2affea1da59c5f5 (diff)
downloadlwn-37fb3a30b46237f23cfdf7ee09d49f9888dd13bf.tar.gz
lwn-37fb3a30b46237f23cfdf7ee09d49f9888dd13bf.zip
fuse: fix flock
Commit a9ff4f87 "fuse: support BSD locking semantics" overlooked a number of issues with supporing flock locks over existing POSIX locking infrastructure: - it's not backward compatible, passing flock(2) calls to userspace unconditionally (if userspace sets FUSE_POSIX_LOCKS) - it doesn't cater for the fact that flock locks are automatically unlocked on file release - it doesn't take into account the fact that flock exclusive locks (write locks) don't need an fd opened for write. The last one invalidates the original premise of the patch that flock locks can be emulated with POSIX locks. This patch fixes the first two issues. The last one needs to be fixed in userspace if the filesystem assumed that a write lock will happen only on a file operned for write (as in the case of the current fuse library). Reported-by: Sebastian Pipping <webmaster@hartwork.org> Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Diffstat (limited to 'fs/fuse')
-rw-r--r--fs/fuse/file.c11
-rw-r--r--fs/fuse/fuse_i.h8
-rw-r--r--fs/fuse/inode.c8
3 files changed, 24 insertions, 3 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 82a66466a24c..e32784924355 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -245,6 +245,12 @@ void fuse_release_common(struct file *file, int opcode)
req = ff->reserved_req;
fuse_prepare_release(ff, file->f_flags, opcode);
+ if (ff->flock) {
+ struct fuse_release_in *inarg = &req->misc.release.in;
+ inarg->release_flags |= FUSE_RELEASE_FLOCK_UNLOCK;
+ inarg->lock_owner = fuse_lock_owner_id(ff->fc,
+ (fl_owner_t) file);
+ }
/* Hold vfsmount and dentry until release is finished */
path_get(&file->f_path);
req->misc.release.path = file->f_path;
@@ -1547,11 +1553,14 @@ static int fuse_file_flock(struct file *file, int cmd, struct file_lock *fl)
struct fuse_conn *fc = get_fuse_conn(inode);
int err;
- if (fc->no_lock) {
+ if (fc->no_flock) {
err = flock_lock_file_wait(file, fl);
} else {
+ struct fuse_file *ff = file->private_data;
+
/* emulate flock with POSIX locks */
fl->fl_owner = (fl_owner_t) file;
+ ff->flock = true;
err = fuse_setlk(file, fl, 1);
}
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index b788becada76..eb8c6135fbbf 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -135,6 +135,9 @@ struct fuse_file {
/** Wait queue head for poll */
wait_queue_head_t poll_wait;
+
+ /** Has flock been performed on this file? */
+ bool flock:1;
};
/** One input argument of a request */
@@ -448,7 +451,7 @@ struct fuse_conn {
/** Is removexattr not implemented by fs? */
unsigned no_removexattr:1;
- /** Are file locking primitives not implemented by fs? */
+ /** Are posix file locking primitives not implemented by fs? */
unsigned no_lock:1;
/** Is access not implemented by fs? */
@@ -472,6 +475,9 @@ struct fuse_conn {
/** Don't apply umask to creation modes */
unsigned dont_mask:1;
+ /** Are BSD file locking primitives not implemented by fs? */
+ unsigned no_flock:1;
+
/** The number of requests waiting for completion */
atomic_t num_waiting;
diff --git a/fs/fuse/inode.c b/fs/fuse/inode.c
index 5354906e797c..f541d639844b 100644
--- a/fs/fuse/inode.c
+++ b/fs/fuse/inode.c
@@ -809,6 +809,10 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
fc->async_read = 1;
if (!(arg->flags & FUSE_POSIX_LOCKS))
fc->no_lock = 1;
+ if (arg->minor >= 17) {
+ if (!(arg->flags & FUSE_FLOCK_LOCKS))
+ fc->no_flock = 1;
+ }
if (arg->flags & FUSE_ATOMIC_O_TRUNC)
fc->atomic_o_trunc = 1;
if (arg->minor >= 9) {
@@ -823,6 +827,7 @@ static void process_init_reply(struct fuse_conn *fc, struct fuse_req *req)
} else {
ra_pages = fc->max_read / PAGE_CACHE_SIZE;
fc->no_lock = 1;
+ fc->no_flock = 1;
}
fc->bdi.ra_pages = min(fc->bdi.ra_pages, ra_pages);
@@ -843,7 +848,8 @@ static void fuse_send_init(struct fuse_conn *fc, struct fuse_req *req)
arg->minor = FUSE_KERNEL_MINOR_VERSION;
arg->max_readahead = fc->bdi.ra_pages * PAGE_CACHE_SIZE;
arg->flags |= FUSE_ASYNC_READ | FUSE_POSIX_LOCKS | FUSE_ATOMIC_O_TRUNC |
- FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK;
+ FUSE_EXPORT_SUPPORT | FUSE_BIG_WRITES | FUSE_DONT_MASK |
+ FUSE_FLOCK_LOCKS;
req->in.h.opcode = FUSE_INIT;
req->in.numargs = 1;
req->in.args[0].size = sizeof(*arg);