[PATCH] v9fs: signal handling fixes

Multiple races can happen when v9fs is interrupted by a signal and Tflush
message is sent to the server.  After v9fs sends Tflush it doesn't wait
until it receives Rflush, and possibly the response of the original
message.  This behavior may confuse v9fs what fids are allocated by the
file server.

This patch fixes the races and the fid allocation.

Signed-off-by: Latchesar Ionkov <lucho@ionkov.net>
Cc: Eric Van Hensbergen <ericvh@hera.kernel.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 16 insertions, 3 deletions

diff --git a/fs/9p/vfs_inode.c b/fs/9p/vfs_inode.c
index 133db366d306..2cb87ba4b1c1 100644
--- a/fs/9p/vfs_inode.c
+++ b/fs/9p/vfs_inode.c
@@ -270,7 +270,10 @@ v9fs_create(struct v9fs_session_info *v9ses, u32 pfid, char *name, u32 perm,
         err = v9fs_t_walk(v9ses, pfid, fid, NULL, &fcall);
         if (err < 0) {
                 PRINT_FCALL_ERROR("clone error", fcall);
-                goto put_fid;
+                if (fcall && fcall->id == RWALK)
+                        goto clunk_fid;
+                else
+                        goto put_fid;
         }
         kfree(fcall);
 
@@ -322,6 +325,9 @@ v9fs_clone_walk(struct v9fs_session_info *v9ses, u32 fid, struct dentry *dentry)
                 &fcall);
 
         if (err < 0) {
+                if (fcall && fcall->id == RWALK)
+                        goto clunk_fid;
+
                 PRINT_FCALL_ERROR("walk error", fcall);
                 v9fs_put_idpool(nfid, &v9ses->fidpool);
                 goto error;
@@ -640,19 +646,26 @@ static struct dentry *v9fs_vfs_lookup(struct inode *dir, struct dentry *dentry,
         }
 
         result = v9fs_t_walk(v9ses, dirfidnum, newfid,
-                (char *)dentry->d_name.name, NULL);
+                (char *)dentry->d_name.name, &fcall);
+
         if (result < 0) {
-                v9fs_put_idpool(newfid, &v9ses->fidpool);
+                if (fcall && fcall->id == RWALK)
+                        v9fs_t_clunk(v9ses, newfid);
+                else
+                        v9fs_put_idpool(newfid, &v9ses->fidpool);
+
                 if (result == -ENOENT) {
                         d_add(dentry, NULL);
                         dprintk(DEBUG_VFS,
                                 "Return negative dentry %p count %d\n",
                                 dentry, atomic_read(&dentry->d_count));
+                        kfree(fcall);
                         return NULL;
                 }
                 dprintk(DEBUG_ERROR, "walk error:%d\n", result);
                 goto FreeFcall;
         }
+        kfree(fcall);
 
         result = v9fs_t_stat(v9ses, newfid, &fcall);
         if (result < 0) {