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authorMiklos Szeredi <mszeredi@suse.cz>2011-08-08 18:08:08 +0400
committerMiklos Szeredi <mszeredi@suse.cz>2011-08-08 18:08:08 +0400
commit37fb3a30b46237f23cfdf7ee09d49f9888dd13bf (patch)
treec36910e300ade812159d12218fdf122b3d2ef3de /fs/fuse/inode.c
parenta2daff6803a384ce065e3681a2affea1da59c5f5 (diff)
downloadlinux-37fb3a30b46237f23cfdf7ee09d49f9888dd13bf.tar.xz
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/inode.c')
-rw-r--r--fs/fuse/inode.c8
1 files changed, 7 insertions, 1 deletions
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);