[PATCH] FUSE: atomic create+open

This patch adds an atomic create+open operation.  This does not yet work if
the file type changes between lookup and create+open, but solves the
permission checking problems for the separte create and open methods.

Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 211 insertions, 48 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index a6f90a6c754a..8f873e621f41 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -184,6 +184,13 @@ static void request_end(struct fuse_conn *fc, struct fuse_req *req)
                    fuse_putback_request() */
                 for (i = 1; i < FUSE_MAX_OUTSTANDING; i++)
                         up(&fc->outstanding_sem);
+        } else if (req->in.h.opcode == FUSE_RELEASE && req->inode == NULL) {
+                /* Special case for failed iget in CREATE */
+                u64 nodeid = req->in.h.nodeid;
+                __fuse_get_request(req);
+                fuse_reset_request(req);
+                fuse_send_forget(fc, req, nodeid, 1);
+                putback = 0;
         }
         if (putback)
                 fuse_putback_request(fc, req);
diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 4bc1afcc476d..83be119ef067 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -13,6 +13,7 @@
 #include <linux/gfp.h>
 #include <linux/sched.h>
 #include <linux/namei.h>
+#include <linux/mount.h>
 
 static inline unsigned long time_to_jiffies(unsigned long sec,
                                             unsigned long nsec)
@@ -134,6 +135,101 @@ static void fuse_invalidate_entry(struct dentry *entry)
         entry->d_time = jiffies - 1;
 }
 
+static int fuse_create_open(struct inode *dir, struct dentry *entry, int mode,
+                            struct nameidata *nd)
+{
+        int err;
+        struct inode *inode;
+        struct fuse_conn *fc = get_fuse_conn(dir);
+        struct fuse_req *req;
+        struct fuse_open_in inarg;
+        struct fuse_open_out outopen;
+        struct fuse_entry_out outentry;
+        struct fuse_inode *fi;
+        struct fuse_file *ff;
+        struct file *file;
+        int flags = nd->intent.open.flags - 1;
+
+        err = -ENOSYS;
+        if (fc->no_create)
+                goto out;
+
+        err = -ENAMETOOLONG;
+        if (entry->d_name.len > FUSE_NAME_MAX)
+                goto out;
+
+        err = -EINTR;
+        req = fuse_get_request(fc);
+        if (!req)
+                goto out;
+
+        ff = fuse_file_alloc();
+        if (!ff)
+                goto out_put_request;
+
+        flags &= ~O_NOCTTY;
+        memset(&inarg, 0, sizeof(inarg));
+        inarg.flags = flags;
+        inarg.mode = mode;
+        req->in.h.opcode = FUSE_CREATE;
+        req->in.h.nodeid = get_node_id(dir);
+        req->inode = dir;
+        req->in.numargs = 2;
+        req->in.args[0].size = sizeof(inarg);
+        req->in.args[0].value = &inarg;
+        req->in.args[1].size = entry->d_name.len + 1;
+        req->in.args[1].value = entry->d_name.name;
+        req->out.numargs = 2;
+        req->out.args[0].size = sizeof(outentry);
+        req->out.args[0].value = &outentry;
+        req->out.args[1].size = sizeof(outopen);
+        req->out.args[1].value = &outopen;
+        request_send(fc, req);
+        err = req->out.h.error;
+        if (err) {
+                if (err == -ENOSYS)
+                        fc->no_create = 1;
+                goto out_free_ff;
+        }
+
+        err = -EIO;
+        if (!S_ISREG(outentry.attr.mode))
+                goto out_free_ff;
+
+        inode = fuse_iget(dir->i_sb, outentry.nodeid, outentry.generation,
+                          &outentry.attr);
+        err = -ENOMEM;
+        if (!inode) {
+                flags &= ~(O_CREAT | O_EXCL | O_TRUNC);
+                ff->fh = outopen.fh;
+                fuse_send_release(fc, ff, outentry.nodeid, NULL, flags, 0);
+                goto out_put_request;
+        }
+        fuse_put_request(fc, req);
+        entry->d_time = time_to_jiffies(outentry.entry_valid,
+                                        outentry.entry_valid_nsec);
+        fi = get_fuse_inode(inode);
+        fi->i_time = time_to_jiffies(outentry.attr_valid,
+                                     outentry.attr_valid_nsec);
+
+        d_instantiate(entry, inode);
+        file = lookup_instantiate_filp(nd, entry, generic_file_open);
+        if (IS_ERR(file)) {
+                ff->fh = outopen.fh;
+                fuse_send_release(fc, ff, outentry.nodeid, inode, flags, 0);
+                return PTR_ERR(file);
+        }
+        fuse_finish_open(inode, file, ff, &outopen);
+        return 0;
+
+ out_free_ff:
+        fuse_file_free(ff);
+ out_put_request:
+        fuse_put_request(fc, req);
+ out:
+        return err;
+}
+
 static int create_new_entry(struct fuse_conn *fc, struct fuse_req *req,
                             struct inode *dir, struct dentry *entry,
                             int mode)
@@ -208,6 +304,12 @@ static int fuse_mknod(struct inode *dir, struct dentry *entry, int mode,
 static int fuse_create(struct inode *dir, struct dentry *entry, int mode,
                        struct nameidata *nd)
 {
+        if (nd && (nd->flags & LOOKUP_CREATE)) {
+                int err = fuse_create_open(dir, entry, mode, nd);
+                if (err != -ENOSYS)
+                        return err;
+                /* Fall back on mknod */
+        }
         return fuse_mknod(dir, entry, mode, 0);
 }
 
@@ -767,7 +869,9 @@ static struct dentry *fuse_lookup(struct inode *dir, struct dentry *entry,
                                   struct nameidata *nd)
 {
         struct inode *inode;
-        int err = fuse_lookup_iget(dir, entry, &inode);
+        int err;
+
+        err = fuse_lookup_iget(dir, entry, &inode);
         if (err)
                 return ERR_PTR(err);
         if (inode && S_ISDIR(inode->i_mode)) {
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 657ab11c173b..2ca86141d13a 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -14,11 +14,69 @@
 
 static struct file_operations fuse_direct_io_file_operations;
 
-int fuse_open_common(struct inode *inode, struct file *file, int isdir)
+static int fuse_send_open(struct inode *inode, struct file *file, int isdir,
+                          struct fuse_open_out *outargp)
 {
         struct fuse_conn *fc = get_fuse_conn(inode);
-        struct fuse_req *req;
         struct fuse_open_in inarg;
+        struct fuse_req *req;
+        int err;
+
+        req = fuse_get_request(fc);
+        if (!req)
+                return -EINTR;
+
+        memset(&inarg, 0, sizeof(inarg));
+        inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
+        req->in.h.opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
+        req->in.h.nodeid = get_node_id(inode);
+        req->inode = inode;
+        req->in.numargs = 1;
+        req->in.args[0].size = sizeof(inarg);
+        req->in.args[0].value = &inarg;
+        req->out.numargs = 1;
+        req->out.args[0].size = sizeof(*outargp);
+        req->out.args[0].value = outargp;
+        request_send(fc, req);
+        err = req->out.h.error;
+        fuse_put_request(fc, req);
+
+        return err;
+}
+
+struct fuse_file *fuse_file_alloc(void)
+{
+        struct fuse_file *ff;
+        ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL);
+        if (ff) {
+                ff->release_req = fuse_request_alloc();
+                if (!ff->release_req) {
+                        kfree(ff);
+                        ff = NULL;
+                }
+        }
+        return ff;
+}
+
+void fuse_file_free(struct fuse_file *ff)
+{
+        fuse_request_free(ff->release_req);
+        kfree(ff);
+}
+
+void fuse_finish_open(struct inode *inode, struct file *file,
+                      struct fuse_file *ff, struct fuse_open_out *outarg)
+{
+        if (outarg->open_flags & FOPEN_DIRECT_IO)
+                file->f_op = &fuse_direct_io_file_operations;
+        if (!(outarg->open_flags & FOPEN_KEEP_CACHE))
+                invalidate_inode_pages(inode->i_mapping);
+        ff->fh = outarg->fh;
+        file->private_data = ff;
+}
+
+int fuse_open_common(struct inode *inode, struct file *file, int isdir)
+{
         struct fuse_open_out outarg;
         struct fuse_file *ff;
         int err;
@@ -34,73 +92,53 @@ int fuse_open_common(struct inode *inode, struct file *file, int isdir)
         /* If opening the root node, no lookup has been performed on
            it, so the attributes must be refreshed */
         if (get_node_id(inode) == FUSE_ROOT_ID) {
-                int err = fuse_do_getattr(inode);
+                err = fuse_do_getattr(inode);
                 if (err)
                         return err;
         }
 
-        req = fuse_get_request(fc);
-        if (!req)
-                return -EINTR;
-
-        err = -ENOMEM;
-        ff = kmalloc(sizeof(struct fuse_file), GFP_KERNEL);
+        ff = fuse_file_alloc();
         if (!ff)
-                goto out_put_request;
+                return -ENOMEM;
 
-        ff->release_req = fuse_request_alloc();
-        if (!ff->release_req) {
-                kfree(ff);
-                goto out_put_request;
-        }
-
-        memset(&inarg, 0, sizeof(inarg));
-        inarg.flags = file->f_flags & ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
-        req->in.h.opcode = isdir ? FUSE_OPENDIR : FUSE_OPEN;
-        req->in.h.nodeid = get_node_id(inode);
-        req->inode = inode;
-        req->in.numargs = 1;
-        req->in.args[0].size = sizeof(inarg);
-        req->in.args[0].value = &inarg;
-        req->out.numargs = 1;
-        req->out.args[0].size = sizeof(outarg);
-        req->out.args[0].value = &outarg;
-        request_send(fc, req);
-        err = req->out.h.error;
-        if (err) {
-                fuse_request_free(ff->release_req);
-                kfree(ff);
-        } else {
-                if (!isdir && (outarg.open_flags & FOPEN_DIRECT_IO))
-                        file->f_op = &fuse_direct_io_file_operations;
-                if (!(outarg.open_flags & FOPEN_KEEP_CACHE))
-                        invalidate_inode_pages(inode->i_mapping);
-                ff->fh = outarg.fh;
-                file->private_data = ff;
+        err = fuse_send_open(inode, file, isdir, &outarg);
+        if (err)
+                fuse_file_free(ff);
+        else {
+                if (isdir)
+                        outarg.open_flags &= ~FOPEN_DIRECT_IO;
+                fuse_finish_open(inode, file, ff, &outarg);
         }
 
- out_put_request:
-        fuse_put_request(fc, req);
         return err;
 }
 
-int fuse_release_common(struct inode *inode, struct file *file, int isdir)
+void fuse_send_release(struct fuse_conn *fc, struct fuse_file *ff,
+                       u64 nodeid, struct inode *inode, int flags, int isdir)
 {
-        struct fuse_conn *fc = get_fuse_conn(inode);
-        struct fuse_file *ff = file->private_data;
-        struct fuse_req *req = ff->release_req;
+        struct fuse_req * req = ff->release_req;
         struct fuse_release_in *inarg = &req->misc.release_in;
 
         inarg->fh = ff->fh;
-        inarg->flags = file->f_flags & ~O_EXCL;
+        inarg->flags = flags;
         req->in.h.opcode = isdir ? FUSE_RELEASEDIR : FUSE_RELEASE;
-        req->in.h.nodeid = get_node_id(inode);
+        req->in.h.nodeid = nodeid;
         req->inode = inode;
         req->in.numargs = 1;
         req->in.args[0].size = sizeof(struct fuse_release_in);
         req->in.args[0].value = inarg;
         request_send_background(fc, req);
         kfree(ff);
+}
+
+int fuse_release_common(struct inode *inode, struct file *file, int isdir)
+{
+        struct fuse_file *ff = file->private_data;
+        if (ff) {
+                struct fuse_conn *fc = get_fuse_conn(inode);
+                u64 nodeid = get_node_id(inode);
+                fuse_send_release(fc, ff, nodeid, inode, file->f_flags, isdir);
+        }
 
         /* Return value is ignored by VFS */
         return 0;
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index c4e8c3b47982..0ea5301f86be 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -269,6 +269,9 @@ struct fuse_conn {
         /** Is access not implemented by fs? */
         unsigned no_access : 1;
 
+        /** Is create not implemented by fs? */
+        unsigned no_create : 1;
+
         /** Backing dev info */
         struct backing_dev_info bdi;
 };
@@ -340,6 +343,17 @@ size_t fuse_send_read_common(struct fuse_req *req, struct file *file,
  */
 int fuse_open_common(struct inode *inode, struct file *file, int isdir);
 
+struct fuse_file *fuse_file_alloc(void);
+void fuse_file_free(struct fuse_file *ff);
+void fuse_finish_open(struct inode *inode, struct file *file,
+                      struct fuse_file *ff, struct fuse_open_out *outarg);
+
+/**
+ * Send a RELEASE request
+ */
+void fuse_send_release(struct fuse_conn *fc, struct fuse_file *ff,
+                       u64 nodeid, struct inode *inode, int flags, int isdir);
+
 /**
  * Send RELEASE or RELEASEDIR request
  */