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Sat, 22 Jul 2023 19:38:13 +0000 From: Ajay Kaher To: rostedt@goodmis.org, shuah@kernel.org, mhiramat@kernel.org Cc: chinglinyu@google.com, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-trace-kernel@vger.kernel.org, lkp@intel.com, namit@vmware.com, oe-lkp@lists.linux.dev, akaher@vmware.com, amakhalov@vmware.com, er.ajay.kaher@gmail.com, srivatsa@csail.mit.edu, tkundu@vmware.com, vsirnapalli@vmware.com Subject: [PATCH v5 07/10] eventfs: Implement functions to create files and dirs when accessed Date: Sun, 23 Jul 2023 01:07:02 +0530 Message-Id: <1690054625-31939-8-git-send-email-akaher@vmware.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1690054625-31939-1-git-send-email-akaher@vmware.com> References: <1690054625-31939-1-git-send-email-akaher@vmware.com> X-ClientProxiedBy: BY5PR20CA0009.namprd20.prod.outlook.com (2603:10b6:a03:1f4::22) To PH0PR05MB8703.namprd05.prod.outlook.com (2603:10b6:510:bd::5) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH0PR05MB8703:EE_|MN0PR05MB9005:EE_ X-MS-Office365-Filtering-Correlation-Id: d543070d-006a-4f31-d3e6-08db8aeb3067 X-LD-Processed: b39138ca-3cee-4b4a-a4d6-cd83d9dd62f0,ExtAddr X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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The functions will be called from the lookup operation of the inode_operations or from the open function of file_operations. Signed-off-by: Ajay Kaher Co-developed-by: Steven Rostedt (VMware) Signed-off-by: Steven Rostedt (VMware) Tested-by: Ching-lin Yu --- fs/tracefs/event_inode.c | 55 +++++++++++++++++++++++++++-- fs/tracefs/inode.c | 74 ++++++++++++++++++++++++++++++++++++++++ include/linux/tracefs.h | 7 ++++ 3 files changed, 134 insertions(+), 2 deletions(-) diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index a3c1b8bf7192..af70d6ffb923 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -101,7 +101,34 @@ static struct dentry *create_file(const char *name, umode_t mode, struct dentry *parent, void *data, const struct file_operations *fop) { - return NULL; + struct tracefs_inode *ti; + struct dentry *dentry; + struct inode *inode; + + if (!(mode & S_IFMT)) + mode |= S_IFREG; + + if (WARN_ON_ONCE(!S_ISREG(mode))) + return NULL; + + dentry = eventfs_start_creating(name, parent); + + if (IS_ERR(dentry)) + return dentry; + + inode = tracefs_get_inode(dentry->d_sb); + if (unlikely(!inode)) + return eventfs_failed_creating(dentry); + + inode->i_mode = mode; + inode->i_fop = fop; + inode->i_private = data; + + ti = get_tracefs(inode); + ti->flags |= TRACEFS_EVENT_INODE; + d_instantiate(dentry, inode); + fsnotify_create(dentry->d_parent->d_inode, dentry); + return eventfs_end_creating(dentry); }; /** @@ -123,7 +150,31 @@ static struct dentry *create_file(const char *name, umode_t mode, */ static struct dentry *create_dir(const char *name, struct dentry *parent, void *data) { - return NULL; + struct tracefs_inode *ti; + struct dentry *dentry; + struct inode *inode; + + dentry = eventfs_start_creating(name, parent); + if (IS_ERR(dentry)) + return dentry; + + inode = tracefs_get_inode(dentry->d_sb); + if (unlikely(!inode)) + return eventfs_failed_creating(dentry); + + inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; + inode->i_op = &eventfs_root_dir_inode_operations; + inode->i_fop = &eventfs_file_operations; + inode->i_private = data; + + ti = get_tracefs(inode); + ti->flags |= TRACEFS_EVENT_INODE; + + inc_nlink(inode); + d_instantiate(dentry, inode); + inc_nlink(dentry->d_parent->d_inode); + fsnotify_mkdir(dentry->d_parent->d_inode, dentry); + return eventfs_end_creating(dentry); } /** diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index 4acc4b4dfd22..d9273066f25f 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -474,6 +474,80 @@ struct dentry *tracefs_end_creating(struct dentry *dentry) return dentry; } +/** + * eventfs_start_creating - start the process of creating a dentry + * @name: Name of the file created for the dentry + * @parent: The parent dentry where this dentry will be created + * + * This is a simple helper function for the dynamically created eventfs + * files. When the directory of the eventfs files are accessed, their + * dentries are created on the fly. This function is used to start that + * process. + */ +struct dentry *eventfs_start_creating(const char *name, struct dentry *parent) +{ + struct dentry *dentry; + int error; + + error = simple_pin_fs(&trace_fs_type, &tracefs_mount, + &tracefs_mount_count); + if (error) + return ERR_PTR(error); + + /* + * If the parent is not specified, we create it in the root. + * We need the root dentry to do this, which is in the super + * block. A pointer to that is in the struct vfsmount that we + * have around. + */ + if (!parent) + parent = tracefs_mount->mnt_root; + + if (unlikely(IS_DEADDIR(parent->d_inode))) + dentry = ERR_PTR(-ENOENT); + else + dentry = lookup_one_len(name, parent, strlen(name)); + + if (!IS_ERR(dentry) && dentry->d_inode) { + dput(dentry); + dentry = ERR_PTR(-EEXIST); + } + + if (IS_ERR(dentry)) + simple_release_fs(&tracefs_mount, &tracefs_mount_count); + + return dentry; +} + +/** + * eventfs_failed_creating - clean up a failed eventfs dentry creation + * @dentry: The dentry to clean up + * + * If after calling eventfs_start_creating(), a failure is detected, the + * resources created by eventfs_start_creating() needs to be cleaned up. In + * that case, this function should be called to perform that clean up. + */ +struct dentry *eventfs_failed_creating(struct dentry *dentry) +{ + dput(dentry); + simple_release_fs(&tracefs_mount, &tracefs_mount_count); + return NULL; +} + +/** + * eventfs_end_creating - Finish the process of creating a eventfs dentry + * @dentry: The dentry that has successfully been created. + * + * This function is currently just a place holder to match + * eventfs_start_creating(). In case any synchronization needs to be added, + * this function will be used to implement that without having to modify + * the callers of eventfs_start_creating(). + */ +struct dentry *eventfs_end_creating(struct dentry *dentry) +{ + return dentry; +} + /** * tracefs_create_file - create a file in the tracefs filesystem * @name: a pointer to a string containing the name of the file to create. diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h index 54c9cbd0389b..cdb21d63a127 100644 --- a/include/linux/tracefs.h +++ b/include/linux/tracefs.h @@ -23,6 +23,13 @@ struct file_operations; struct eventfs_file; +struct dentry *eventfs_start_creating(const char *name, + struct dentry *parent); + +struct dentry *eventfs_failed_creating(struct dentry *dentry); + +struct dentry *eventfs_end_creating(struct dentry *dentry); + struct dentry *eventfs_create_events_dir(const char *name, struct dentry *parent);