diff options
Diffstat (limited to 'fs/tracefs/event_inode.c')
| -rw-r--r-- | fs/tracefs/event_inode.c | 1093 |
1 files changed, 634 insertions, 459 deletions
diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 8c8d64e76103..f8a594a50ae6 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -2,8 +2,9 @@ /* * event_inode.c - part of tracefs, a pseudo file system for activating tracing * - * Copyright (C) 2020-23 VMware Inc, author: Steven Rostedt (VMware) <rostedt@goodmis.org> + * Copyright (C) 2020-23 VMware Inc, author: Steven Rostedt <rostedt@goodmis.org> * Copyright (C) 2020-23 VMware Inc, author: Ajay Kaher <akaher@vmware.com> + * Copyright (C) 2023 Google, author: Steven Rostedt <rostedt@goodmis.org> * * eventfs is used to dynamically create inodes and dentries based on the * meta data provided by the tracing system. @@ -23,48 +24,30 @@ #include <linux/delay.h> #include "internal.h" -struct eventfs_inode { - struct list_head e_top_files; -}; +/* + * eventfs_mutex protects the eventfs_inode (ei) dentry. Any access + * to the ei->dentry must be done under this mutex and after checking + * if ei->is_freed is not set. The ei->dentry is released under the + * mutex at the same time ei->is_freed is set. If ei->is_freed is set + * then the ei->dentry is invalid. + */ +static DEFINE_MUTEX(eventfs_mutex); /* - * struct eventfs_file - hold the properties of the eventfs files and - * directories. - * @name: the name of the file or directory to create - * @d_parent: holds parent's dentry - * @dentry: once accessed holds dentry - * @list: file or directory to be added to parent directory - * @ei: list of files and directories within directory - * @fop: file_operations for file or directory - * @iop: inode_operations for file or directory - * @data: something that the caller will want to get to later on - * @mode: the permission that the file or directory should have + * The eventfs_inode (ei) itself is protected by SRCU. It is released from + * its parent's list and will have is_freed set (under eventfs_mutex). + * After the SRCU grace period is over, the ei may be freed. */ -struct eventfs_file { - const char *name; - struct dentry *d_parent; - struct dentry *dentry; - struct list_head list; - struct eventfs_inode *ei; - const struct file_operations *fop; - const struct inode_operations *iop; - /* - * Union - used for deletion - * @del_list: list of eventfs_file to delete - * @rcu: eventfs_file to delete in RCU - * @is_freed: node is freed if one of the above is set - */ - union { - struct list_head del_list; - struct rcu_head rcu; - unsigned long is_freed; - }; - void *data; - umode_t mode; +DEFINE_STATIC_SRCU(eventfs_srcu); + +/* Mode is unsigned short, use the upper bits for flags */ +enum { + EVENTFS_SAVE_MODE = BIT(16), + EVENTFS_SAVE_UID = BIT(17), + EVENTFS_SAVE_GID = BIT(18), }; -static DEFINE_MUTEX(eventfs_mutex); -DEFINE_STATIC_SRCU(eventfs_srcu); +#define EVENTFS_MODE_MASK (EVENTFS_SAVE_MODE - 1) static struct dentry *eventfs_root_lookup(struct inode *dir, struct dentry *dentry, @@ -73,8 +56,88 @@ static int dcache_dir_open_wrapper(struct inode *inode, struct file *file); static int dcache_readdir_wrapper(struct file *file, struct dir_context *ctx); static int eventfs_release(struct inode *inode, struct file *file); +static void update_attr(struct eventfs_attr *attr, struct iattr *iattr) +{ + unsigned int ia_valid = iattr->ia_valid; + + if (ia_valid & ATTR_MODE) { + attr->mode = (attr->mode & ~EVENTFS_MODE_MASK) | + (iattr->ia_mode & EVENTFS_MODE_MASK) | + EVENTFS_SAVE_MODE; + } + if (ia_valid & ATTR_UID) { + attr->mode |= EVENTFS_SAVE_UID; + attr->uid = iattr->ia_uid; + } + if (ia_valid & ATTR_GID) { + attr->mode |= EVENTFS_SAVE_GID; + attr->gid = iattr->ia_gid; + } +} + +static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry, + struct iattr *iattr) +{ + const struct eventfs_entry *entry; + struct eventfs_inode *ei; + const char *name; + int ret; + + mutex_lock(&eventfs_mutex); + ei = dentry->d_fsdata; + if (ei->is_freed) { + /* Do not allow changes if the event is about to be removed. */ + mutex_unlock(&eventfs_mutex); + return -ENODEV; + } + + /* Preallocate the children mode array if necessary */ + if (!(dentry->d_inode->i_mode & S_IFDIR)) { + if (!ei->entry_attrs) { + ei->entry_attrs = kzalloc(sizeof(*ei->entry_attrs) * ei->nr_entries, + GFP_KERNEL); + if (!ei->entry_attrs) { + ret = -ENOMEM; + goto out; + } + } + } + + ret = simple_setattr(idmap, dentry, iattr); + if (ret < 0) + goto out; + + /* + * If this is a dir, then update the ei cache, only the file + * mode is saved in the ei->m_children, and the ownership is + * determined by the parent directory. + */ + if (dentry->d_inode->i_mode & S_IFDIR) { + update_attr(&ei->attr, iattr); + + } else { + name = dentry->d_name.name; + + for (int i = 0; i < ei->nr_entries; i++) { + entry = &ei->entries[i]; + if (strcmp(name, entry->name) == 0) { + update_attr(&ei->entry_attrs[i], iattr); + break; + } + } + } + out: + mutex_unlock(&eventfs_mutex); + return ret; +} + static const struct inode_operations eventfs_root_dir_inode_operations = { .lookup = eventfs_root_lookup, + .setattr = eventfs_set_attr, +}; + +static const struct inode_operations eventfs_file_inode_operations = { + .setattr = eventfs_set_attr, }; static const struct file_operations eventfs_file_operations = { @@ -85,26 +148,40 @@ static const struct file_operations eventfs_file_operations = { .release = eventfs_release, }; +static void update_inode_attr(struct inode *inode, struct eventfs_attr *attr, umode_t mode) +{ + if (!attr) { + inode->i_mode = mode; + return; + } + + if (attr->mode & EVENTFS_SAVE_MODE) + inode->i_mode = attr->mode & EVENTFS_MODE_MASK; + else + inode->i_mode = mode; + + if (attr->mode & EVENTFS_SAVE_UID) + inode->i_uid = attr->uid; + + if (attr->mode & EVENTFS_SAVE_GID) + inode->i_gid = attr->gid; +} + /** * create_file - create a file in the tracefs filesystem * @name: the name of the file to create. * @mode: the permission that the file should have. + * @attr: saved attributes changed by user * @parent: parent dentry for this file. * @data: something that the caller will want to get to later on. * @fop: struct file_operations that should be used for this file. * - * This is the basic "create a file" function for tracefs. It allows for a - * wide range of flexibility in creating a file. - * - * This function will return a pointer to a dentry if it succeeds. This - * pointer must be passed to the tracefs_remove() function when the file is - * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. - * - * If tracefs is not enabled in the kernel, the value -%ENODEV will be - * returned. + * This function creates a dentry that represents a file in the eventsfs_inode + * directory. The inode.i_private pointer will point to @data in the open() + * call. */ static struct dentry *create_file(const char *name, umode_t mode, + struct eventfs_attr *attr, struct dentry *parent, void *data, const struct file_operations *fop) { @@ -118,6 +195,7 @@ static struct dentry *create_file(const char *name, umode_t mode, if (WARN_ON_ONCE(!S_ISREG(mode))) return NULL; + WARN_ON_ONCE(!parent); dentry = eventfs_start_creating(name, parent); if (IS_ERR(dentry)) @@ -127,7 +205,10 @@ static struct dentry *create_file(const char *name, umode_t mode, if (unlikely(!inode)) return eventfs_failed_creating(dentry); - inode->i_mode = mode; + /* If the user updated the directory's attributes, use them */ + update_inode_attr(inode, attr, mode); + + inode->i_op = &eventfs_file_inode_operations; inode->i_fop = fop; inode->i_private = data; @@ -140,28 +221,19 @@ static struct dentry *create_file(const char *name, umode_t mode, /** * create_dir - create a dir in the tracefs filesystem - * @name: the name of the file to create. + * @ei: the eventfs_inode that represents the directory to create * @parent: parent dentry for this file. - * @data: something that the caller will want to get to later on. * - * This is the basic "create a dir" function for eventfs. It allows for a - * wide range of flexibility in creating a dir. - * - * This function will return a pointer to a dentry if it succeeds. This - * pointer must be passed to the tracefs_remove() function when the file is - * to be removed (no automatic cleanup happens if your module is unloaded, - * you are responsible here.) If an error occurs, %NULL will be returned. - * - * If tracefs is not enabled in the kernel, the value -%ENODEV will be - * returned. + * This function will create a dentry for a directory represented by + * a eventfs_inode. */ -static struct dentry *create_dir(const char *name, struct dentry *parent, void *data) +static struct dentry *create_dir(struct eventfs_inode *ei, struct dentry *parent) { struct tracefs_inode *ti; struct dentry *dentry; struct inode *inode; - dentry = eventfs_start_creating(name, parent); + dentry = eventfs_start_creating(ei->name, parent); if (IS_ERR(dentry)) return dentry; @@ -169,10 +241,11 @@ static struct dentry *create_dir(const char *name, struct dentry *parent, void * if (unlikely(!inode)) return eventfs_failed_creating(dentry); - inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; + /* If the user updated the directory's attributes, use them */ + update_inode_attr(inode, &ei->attr, 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; @@ -184,117 +257,198 @@ static struct dentry *create_dir(const char *name, struct dentry *parent, void * return eventfs_end_creating(dentry); } +static void free_ei(struct eventfs_inode *ei) +{ + kfree_const(ei->name); + kfree(ei->d_children); + kfree(ei->entry_attrs); + kfree(ei); +} + /** - * eventfs_set_ef_status_free - set the ef->status to free + * eventfs_set_ei_status_free - remove the dentry reference from an eventfs_inode * @ti: the tracefs_inode of the dentry - * @dentry: dentry who's status to be freed + * @dentry: dentry which has the reference to remove. * - * eventfs_set_ef_status_free will be called if no more - * references remain + * Remove the association between a dentry from an eventfs_inode. */ -void eventfs_set_ef_status_free(struct tracefs_inode *ti, struct dentry *dentry) +void eventfs_set_ei_status_free(struct tracefs_inode *ti, struct dentry *dentry) { - struct tracefs_inode *ti_parent; struct eventfs_inode *ei; - struct eventfs_file *ef, *tmp; - - /* The top level events directory may be freed by this */ - if (unlikely(ti->flags & TRACEFS_EVENT_TOP_INODE)) { - LIST_HEAD(ef_del_list); + int i; - mutex_lock(&eventfs_mutex); + mutex_lock(&eventfs_mutex); - ei = ti->private; + ei = dentry->d_fsdata; + if (!ei) + goto out; - /* Record all the top level files */ - list_for_each_entry_srcu(ef, &ei->e_top_files, list, - lockdep_is_held(&eventfs_mutex)) { - list_add_tail(&ef->del_list, &ef_del_list); + /* This could belong to one of the files of the ei */ + if (ei->dentry != dentry) { + for (i = 0; i < ei->nr_entries; i++) { + if (ei->d_children[i] == dentry) + break; } + if (WARN_ON_ONCE(i == ei->nr_entries)) + goto out; + ei->d_children[i] = NULL; + } else if (ei->is_freed) { + free_ei(ei); + } else { + ei->dentry = NULL; + } + + dentry->d_fsdata = NULL; + out: + mutex_unlock(&eventfs_mutex); +} - /* Nothing should access this, but just in case! */ - ti->private = NULL; +/** + * create_file_dentry - create a dentry for a file of an eventfs_inode + * @ei: the eventfs_inode that the file will be created under + * @idx: the index into the d_children[] of the @ei + * @parent: The parent dentry of the created file. + * @name: The name of the file to create + * @mode: The mode of the file. + * @data: The data to use to set the inode of the file with on open() + * @fops: The fops of the file to be created. + * @lookup: If called by the lookup routine, in which case, dput() the created dentry. + * + * Create a dentry for a file of an eventfs_inode @ei and place it into the + * address located at @e_dentry. If the @e_dentry already has a dentry, then + * just do a dget() on it and return. Otherwise create the dentry and attach it. + */ +static struct dentry * +create_file_dentry(struct eventfs_inode *ei, int idx, + struct dentry *parent, const char *name, umode_t mode, void *data, + const struct file_operations *fops, bool lookup) +{ + struct eventfs_attr *attr = NULL; + struct dentry **e_dentry = &ei->d_children[idx]; + struct dentry *dentry; + bool invalidate = false; + mutex_lock(&eventfs_mutex); + if (ei->is_freed) { mutex_unlock(&eventfs_mutex); + return NULL; + } + /* If the e_dentry already has a dentry, use it */ + if (*e_dentry) { + /* lookup does not need to up the ref count */ + if (!lookup) + dget(*e_dentry); + mutex_unlock(&eventfs_mutex); + return *e_dentry; + } - /* Now safely free the top level files and their children */ - list_for_each_entry_safe(ef, tmp, &ef_del_list, del_list) { - list_del(&ef->del_list); - eventfs_remove(ef); - } + /* ei->entry_attrs are protected by SRCU */ + if (ei->entry_attrs) + attr = &ei->entry_attrs[idx]; - kfree(ei); - return; - } + mutex_unlock(&eventfs_mutex); - mutex_lock(&eventfs_mutex); + /* The lookup already has the parent->d_inode locked */ + if (!lookup) + inode_lock(parent->d_inode); - ti_parent = get_tracefs(dentry->d_parent->d_inode); - if (!ti_parent || !(ti_parent->flags & TRACEFS_EVENT_INODE)) - goto out; + dentry = create_file(name, mode, attr, parent, data, fops); - ef = dentry->d_fsdata; - if (!ef) - goto out; + if (!lookup) + inode_unlock(parent->d_inode); - /* - * If ef was freed, then the LSB bit is set for d_fsdata. - * But this should not happen, as it should still have a - * ref count that prevents it. Warn in case it does. - */ - if (WARN_ON_ONCE((unsigned long)ef & 1)) - goto out; + mutex_lock(&eventfs_mutex); - dentry->d_fsdata = NULL; - ef->dentry = NULL; -out: + if (IS_ERR_OR_NULL(dentry)) { + /* + * When the mutex was released, something else could have + * created the dentry for this e_dentry. In which case + * use that one. + * + * Note, with the mutex held, the e_dentry cannot have content + * and the ei->is_freed be true at the same time. + */ + dentry = *e_dentry; + if (WARN_ON_ONCE(dentry && ei->is_freed)) + dentry = NULL; + /* The lookup does not need to up the dentry refcount */ + if (dentry && !lookup) + dget(dentry); + mutex_unlock(&eventfs_mutex); + return dentry; + } + + if (!*e_dentry && !ei->is_freed) { + *e_dentry = dentry; + dentry->d_fsdata = ei; + } else { + /* + * Should never happen unless we get here due to being freed. + * Otherwise it means two dentries exist with the same name. + */ + WARN_ON_ONCE(!ei->is_freed); + invalidate = true; + } mutex_unlock(&eventfs_mutex); + + if (invalidate) + d_invalidate(dentry); + + if (lookup || invalidate) + dput(dentry); + + return invalidate ? NULL : dentry; } /** * eventfs_post_create_dir - post create dir routine - * @ef: eventfs_file of recently created dir + * @ei: eventfs_inode of recently created dir * * Map the meta-data of files within an eventfs dir to their parent dentry */ -static void eventfs_post_create_dir(struct eventfs_file *ef) +static void eventfs_post_create_dir(struct eventfs_inode *ei) { - struct eventfs_file *ef_child; + struct eventfs_inode *ei_child; struct tracefs_inode *ti; + lockdep_assert_held(&eventfs_mutex); + /* srcu lock already held */ /* fill parent-child relation */ - list_for_each_entry_srcu(ef_child, &ef->ei->e_top_files, list, + list_for_each_entry_srcu(ei_child, &ei->children, list, srcu_read_lock_held(&eventfs_srcu)) { - ef_child->d_parent = ef->dentry; + ei_child->d_parent = ei->dentry; } - ti = get_tracefs(ef->dentry->d_inode); - ti->private = ef->ei; + ti = get_tracefs(ei->dentry->d_inode); + ti->private = ei; } /** - * create_dentry - helper function to create dentry - * @ef: eventfs_file of file or directory to create - * @parent: parent dentry - * @lookup: true if called from lookup routine + * create_dir_dentry - Create a directory dentry for the eventfs_inode + * @pei: The eventfs_inode parent of ei. + * @ei: The eventfs_inode to create the directory for + * @parent: The dentry of the parent of this directory + * @lookup: True if this is called by the lookup code * - * Used to create a dentry for file/dir, executes post dentry creation routine + * This creates and attaches a directory dentry to the eventfs_inode @ei. */ static struct dentry * -create_dentry(struct eventfs_file *ef, struct dentry *parent, bool lookup) +create_dir_dentry(struct eventfs_inode *pei, struct eventfs_inode *ei, + struct dentry *parent, bool lookup) { bool invalidate = false; - struct dentry *dentry; + struct dentry *dentry = NULL; mutex_lock(&eventfs_mutex); - if (ef->is_freed) { + if (pei->is_freed || ei->is_freed) { mutex_unlock(&eventfs_mutex); return NULL; } - if (ef->dentry) { - dentry = ef->dentry; - /* On dir open, up the ref count */ + if (ei->dentry) { + /* If the dentry already has a dentry, use it */ + dentry = ei->dentry; + /* lookup does not need to up the ref count */ if (!lookup) dget(dentry); mutex_unlock(&eventfs_mutex); @@ -302,42 +456,44 @@ create_dentry(struct eventfs_file *ef, struct dentry *parent, bool lookup) } mutex_unlock(&eventfs_mutex); + /* The lookup already has the parent->d_inode locked */ if (!lookup) inode_lock(parent->d_inode); - if (ef->ei) - dentry = create_dir(ef->name, parent, ef->data); - else - dentry = create_file(ef->name, ef->mode, parent, - ef->data, ef->fop); + dentry = create_dir(ei, parent); if (!lookup) inode_unlock(parent->d_inode); mutex_lock(&eventfs_mutex); - if (IS_ERR_OR_NULL(dentry)) { - /* If the ef was already updated get it */ - dentry = ef->dentry; + + if (IS_ERR_OR_NULL(dentry) && !ei->is_freed) { + /* + * When the mutex was released, something else could have + * created the dentry for this e_dentry. In which case + * use that one. + * + * Note, with the mutex held, the e_dentry cannot have content + * and the ei->is_freed be true at the same time. + */ + dentry = ei->dentry; if (dentry && !lookup) dget(dentry); mutex_unlock(&eventfs_mutex); return dentry; } - if (!ef->dentry && !ef->is_freed) { - ef->dentry = dentry; - if (ef->ei) - eventfs_post_create_dir(ef); - dentry->d_fsdata = ef; + if (!ei->dentry && !ei->is_freed) { + ei->dentry = dentry; + eventfs_post_create_dir(ei); + dentry->d_fsdata = ei; } else { - /* A race here, should try again (unless freed) */ - invalidate = true; - /* * Should never happen unless we get here due to being freed. * Otherwise it means two dentries exist with the same name. */ - WARN_ON_ONCE(!ef->is_freed); + WARN_ON_ONCE(!ei->is_freed); + invalidate = true; } mutex_unlock(&eventfs_mutex); if (invalidate) @@ -349,50 +505,90 @@ create_dentry(struct eventfs_file *ef, struct dentry *parent, bool lookup) return invalidate ? NULL : dentry; } -static bool match_event_file(struct eventfs_file *ef, const char *name) -{ - bool ret; - - mutex_lock(&eventfs_mutex); - ret = !ef->is_freed && strcmp(ef->name, name) == 0; - mutex_unlock(&eventfs_mutex); - - return ret; -} - /** * eventfs_root_lookup - lookup routine to create file/dir * @dir: in which a lookup is being done * @dentry: file/dir dentry - * @flags: to pass as flags parameter to simple lookup + * @flags: Just passed to simple_lookup() * - * Used to create a dynamic file/dir within @dir. Use the eventfs_inode - * list of meta data to find the information needed to create the file/dir. + * Used to create dynamic file/dir with-in @dir, search with-in @ei + * list, if @dentry found go ahead and create the file/dir */ + static struct dentry *eventfs_root_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) { + const struct file_operations *fops; + const struct eventfs_entry *entry; + struct eventfs_inode *ei_child; struct tracefs_inode *ti; struct eventfs_inode *ei; - struct eventfs_file *ef; + struct dentry *ei_dentry = NULL; struct dentry *ret = NULL; + const char *name = dentry->d_name.name; + bool created = false; + umode_t mode; + void *data; int idx; + int i; + int r; ti = get_tracefs(dir); if (!(ti->flags & TRACEFS_EVENT_INODE)) return NULL; - ei = ti->private; + /* Grab srcu to prevent the ei from going away */ idx = srcu_read_lock(&eventfs_srcu); - list_for_each_entry_srcu(ef, &ei->e_top_files, list, + + /* + * Grab the eventfs_mutex to consistent value from ti->private. + * This s + */ + mutex_lock(&eventfs_mutex); + ei = READ_ONCE(ti->private); + if (ei && !ei->is_freed) + ei_dentry = READ_ONCE(ei->dentry); + mutex_unlock(&eventfs_mutex); + + if (!ei || !ei_dentry) + goto out; + + data = ei->data; + + list_for_each_entry_srcu(ei_child, &ei->children, list, srcu_read_lock_held(&eventfs_srcu)) { - if (!match_event_file(ef, dentry->d_name.name)) + if (strcmp(ei_child->name, name) != 0) continue; ret = simple_lookup(dir, dentry, flags); - create_dentry(ef, ef->d_parent, true); + create_dir_dentry(ei, ei_child, ei_dentry, true); + created = true; break; } + + if (created) + goto out; + + for (i = 0; i < ei->nr_entries; i++) { + entry = &ei->entries[i]; + if (strcmp(name, entry->name) == 0) { + void *cdata = data; + mutex_lock(&eventfs_mutex); + /* If ei->is_freed, then the event itself may be too */ + if (!ei->is_freed) + r = entry->callback(name, &mode, &cdata, &fops); + else + r = -1; + mutex_unlock(&eventfs_mutex); + if (r <= 0) + continue; + ret = simple_lookup(dir, dentry, flags); + create_file_dentry(ei, i, ei_dentry, name, mode, cdata, + fops, true); + break; + } + } + out: srcu_read_unlock(&eventfs_srcu, idx); return ret; } @@ -432,29 +628,48 @@ static int eventfs_release(struct inode *inode, struct file *file) return dcache_dir_close(inode, file); } +static int add_dentries(struct dentry ***dentries, struct dentry *d, int cnt) +{ + struct dentry **tmp; + + tmp = krealloc(*dentries, sizeof(d) * (cnt + 2), GFP_KERNEL); + if (!tmp) + return -1; + tmp[cnt] = d; + tmp[cnt + 1] = NULL; + *dentries = tmp; + return 0; +} + /** * dcache_dir_open_wrapper - eventfs open wrapper * @inode: not used - * @file: dir to be opened (to create its child) + * @file: dir to be opened (to create it's children) * - * Used to dynamically create the file/dir within @file. @file is really a - * directory and all the files/dirs of the children within @file will be - * created. If any of the files/dirs have already been created, their - * reference count will be incremented. + * Used to dynamic create file/dir with-in @file, all the + * file/dir will be created. If already created then references + * will be increased */ static int dcache_dir_open_wrapper(struct inode *inode, struct file *file) { + const struct file_operations *fops; + const struct eventfs_entry *entry; + struct eventfs_inode *ei_child; struct tracefs_inode *ti; struct eventfs_inode *ei; - struct eventfs_file *ef; struct dentry_list *dlist; struct dentry **dentries = NULL; - struct dentry *dentry = file_dentry(file); + struct dentry *parent = file_dentry(file); struct dentry *d; struct inode *f_inode = file_inode(file); + const char *name = parent->d_name.name; + umode_t mode; + void *data; int cnt = 0; int idx; int ret; + int i; + int r; ti = get_tracefs(f_inode); if (!(ti->flags & TRACEFS_EVENT_INODE)) @@ -463,25 +678,56 @@ static int dcache_dir_open_wrapper(struct inode *inode, struct file *file) if (WARN_ON_ONCE(file->private_data)) return -EINVAL; + idx = srcu_read_lock(&eventfs_srcu); + + mutex_lock(&eventfs_mutex); + ei = READ_ONCE(ti->private); + mutex_unlock(&eventfs_mutex); + + if (!ei) { + srcu_read_unlock(&eventfs_srcu, idx); + return -EINVAL; + } + + + data = ei->data; + dlist = kmalloc(sizeof(*dlist), GFP_KERNEL); - if (!dlist) + if (!dlist) { + srcu_read_unlock(&eventfs_srcu, idx); return -ENOMEM; + } - ei = ti->private; - idx = srcu_read_lock(&eventfs_srcu); - list_for_each_entry_srcu(ef, &ei->e_top_files, list, + list_for_each_entry_srcu(ei_child, &ei->children, list, srcu_read_lock_held(&eventfs_srcu)) { - d = create_dentry(ef, dentry, false); + d = create_dir_dentry(ei, ei_child, parent, false); if (d) { - struct dentry **tmp; + ret = add_dentries(&dentries, d, cnt); + if (ret < 0) + break; + cnt++; + } + } - tmp = krealloc(dentries, sizeof(d) * (cnt + 2), GFP_KERNEL); - if (!tmp) + for (i = 0; i < ei->nr_entries; i++) { + void *cdata = data; + entry = &ei->entries[i]; + name = entry->name; + mutex_lock(&eventfs_mutex); + /* If ei->is_freed, then the event itself may be too */ + if (!ei->is_freed) + r = entry->callback(name, &mode, &cdata, &fops); + else + r = -1; + mutex_unlock(&eventfs_mutex); + if (r <= 0) + continue; + d = create_file_dentry(ei, i, parent, name, mode, cdata, fops, false); + if (d) { + ret = add_dentries(&dentries, d, cnt); + if (ret < 0) break; - tmp[cnt] = d; - tmp[cnt + 1] = NULL; cnt++; - dentries = tmp; } } srcu_read_unlock(&eventfs_srcu, idx); @@ -514,63 +760,104 @@ static int dcache_readdir_wrapper(struct file *file, struct dir_context *ctx) } /** - * eventfs_prepare_ef - helper function to prepare eventfs_file - * @name: the name of the file/directory to create. - * @mode: the permission that the file should have. - * @fop: struct file_operations that should be used for this file/directory. - * @iop: struct inode_operations that should be used for this file/directory. - * @data: something that the caller will want to get to later on. The - * inode.i_private pointer will point to this value on the open() call. + * eventfs_create_dir - Create the eventfs_inode for this directory + * @name: The name of the directory to create. + * @parent: The eventfs_inode of the parent directory. + * @entries: A list of entries that represent the files under this directory + * @size: The number of @entries + * @data: The default data to pass to the files (an entry may override it). + * + * This function creates the descriptor to represent a directory in the + * eventfs. This descriptor is an eventfs_inode, and it is returned to be + * used to create other children underneath. + * + * The @entries is an array of eventfs_entry structures which has: + * const char *name + * eventfs_callback callback; * - * This function allocates and fills the eventfs_file structure. + * The name is the name of the file, and the callback is a pointer to a function + * that will be called when the file is reference (either by lookup or by + * reading a directory). The callback is of the prototype: + * + * int callback(const char *name, umode_t *mode, void **data, + * const struct file_operations **fops); + * + * When a file needs to be created, this callback will be called with + * name = the name of the file being created (so that the same callback + * may be used for multiple files). + * mode = a place to set the file's mode + * data = A pointer to @data, and the callback may replace it, which will + * cause the file created to pass the new data to the open() call. + * fops = the fops to use for the created file. + * + * NB. @callback is called while holding internal locks of the eventfs + * system. The callback must not call any code that might also call into + * the tracefs or eventfs system or it will risk creating a deadlock. */ -static struct eventfs_file *eventfs_prepare_ef(const char *name, umode_t mode, - const struct file_operations *fop, - const struct inode_operations *iop, - void *data) +struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode *parent, + const struct eventfs_entry *entries, + int size, void *data) { - struct eventfs_file *ef; + struct eventfs_inode *ei; - ef = kzalloc(sizeof(*ef), GFP_KERNEL); - if (!ef) + if (!parent) + return ERR_PTR(-EINVAL); + + ei = kzalloc(sizeof(*ei), GFP_KERNEL); + if (!ei) return ERR_PTR(-ENOMEM); - ef->name = kstrdup(name, GFP_KERNEL); - if (!ef->name) { - kfree(ef); + ei->name = kstrdup_const(name, GFP_KERNEL); + if (!ei->name) { + kfree(ei); return ERR_PTR(-ENOMEM); } - if (S_ISDIR(mode)) { - ef->ei = kzalloc(sizeof(*ef->ei), GFP_KERNEL); - if (!ef->ei) { - kfree(ef->name); - kfree(ef); + if (size) { + ei->d_children = kzalloc(sizeof(*ei->d_children) * size, GFP_KERNEL); + if (!ei->d_children) { + kfree_const(ei->name); + kfree(ei); return ERR_PTR(-ENOMEM); } - INIT_LIST_HEAD(&ef->ei->e_top_files); - } else { - ef->ei = NULL; } - ef->iop = iop; - ef->fop = fop; - ef->mode = mode; - ef->data = data; - return ef; + ei->entries = entries; + ei->nr_entries = size; + ei->data = data; + INIT_LIST_HEAD(&ei->children); + INIT_LIST_HEAD(&ei->list); + + mutex_lock(&eventfs_mutex); + if (!parent->is_freed) { + list_add_tail(&ei->list, &parent->children); + ei->d_parent = parent->dentry; + } + mutex_unlock(&eventfs_mutex); + + /* Was the parent freed? */ + if (list_empty(&ei->list)) { + free_ei(ei); + ei = NULL; + } + return ei; } /** - * eventfs_create_events_dir - create the trace event structure - * @name: the name of the directory to create. - * @parent: parent dentry for this file. This should be a directory dentry - * if set. If this parameter is NULL, then the directory will be - * created in the root of the tracefs filesystem. + * eventfs_create_events_dir - create the top level events directory + * @name: The name of the top level directory to create. + * @parent: Parent dentry for this file in the tracefs directory. + * @entries: A list of entries that represent the files under this directory + * @size: The number of @entries + * @data: The default data to pass to the files (an entry may override it). * * This function creates the top of the trace event directory. + * + * See eventfs_create_dir() for use of @entries. */ -struct dentry *eventfs_create_events_dir(const char *name, - struct dentry *parent) +struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry *parent, + const struct eventfs_entry *entries, + int size, void *data) { struct dentry *dentry = tracefs_start_creating(name, parent); struct eventfs_inode *ei; @@ -581,19 +868,32 @@ struct dentry *eventfs_create_events_dir(const char *name, return NULL; if (IS_ERR(dentry)) - return dentry; + return ERR_CAST(dentry); ei = kzalloc(sizeof(*ei), GFP_KERNEL); if (!ei) - return ERR_PTR(-ENOMEM); + goto fail_ei; + inode = tracefs_get_inode(dentry->d_sb); - if (unlikely(!inode)) { - kfree(ei); - tracefs_failed_creating(dentry); - return ERR_PTR(-ENOMEM); + if (unlikely(!inode)) + goto fail; + + if (size) { + ei->d_children = kzalloc(sizeof(*ei->d_children) * size, GFP_KERNEL); + if (!ei->d_children) + goto fail; } - INIT_LIST_HEAD(&ei->e_top_files); + ei->dentry = dentry; + ei->entries = entries; + ei->nr_entries = size; + ei->data = data; + ei->name = kstrdup_const(name, GFP_KERNEL); + if (!ei->name) + goto fail; + + INIT_LIST_HEAD(&ei->children); + INIT_LIST_HEAD(&ei->list); ti = get_tracefs(inode); ti->flags |= TRACEFS_EVENT_INODE | TRACEFS_EVENT_TOP_INODE; @@ -603,198 +903,97 @@ struct dentry *eventfs_create_events_dir(const char *name, inode->i_op = &eventfs_root_dir_inode_operations; inode->i_fop = &eventfs_file_operations; + dentry->d_fsdata = ei; + /* directory inodes start off with i_nlink == 2 (for "." entry) */ inc_nlink(inode); d_instantiate(dentry, inode); inc_nlink(dentry->d_parent->d_inode); fsnotify_mkdir(dentry->d_parent->d_inode, dentry); - return tracefs_end_creating(dentry); -} - -/** - * eventfs_add_subsystem_dir - add eventfs subsystem_dir to list to create later - * @name: the name of the file to create. - * @parent: parent dentry for this dir. - * - * This function adds eventfs subsystem dir to list. - * And all these dirs are created on the fly when they are looked up, - * and the dentry and inodes will be removed when they are done. - */ -struct eventfs_file *eventfs_add_subsystem_dir(const char *name, - struct dentry *parent) -{ - struct tracefs_inode *ti_parent; - struct eventfs_inode *ei_parent; - struct eventfs_file *ef; - - if (security_locked_down(LOCKDOWN_TRACEFS)) - return NULL; - - if (!parent) - return ERR_PTR(-EINVAL); - - ti_parent = get_tracefs(parent->d_inode); - ei_parent = ti_parent->private; + tracefs_end_creating(dentry); - ef = eventfs_prepare_ef(name, S_IFDIR, NULL, NULL, NULL); - if (IS_ERR(ef)) - return ef; + return ei; - mutex_lock(&eventfs_mutex); - list_add_tail(&ef->list, &ei_parent->e_top_files); - ef->d_parent = parent; - mutex_unlock(&eventfs_mutex); - return ef; + fail: + kfree(ei->d_children); + kfree(ei); + fail_ei: + tracefs_failed_creating(dentry); + return ERR_PTR(-ENOMEM); } -/** - * eventfs_add_dir - add eventfs dir to list to create later - * @name: the name of the file to create. - * @ef_parent: parent eventfs_file for this dir. - * - * This function adds eventfs dir to list. - * And all these dirs are created on the fly when they are looked up, - * and the dentry and inodes will be removed when they are done. - */ -struct eventfs_file *eventfs_add_dir(const char *name, - struct eventfs_file *ef_parent) -{ - struct eventfs_file *ef; - - if (security_locked_down(LOCKDOWN_TRACEFS)) - return NULL; - - if (!ef_parent) - return ERR_PTR(-EINVAL); - - ef = eventfs_prepare_ef(name, S_IFDIR, NULL, NULL, NULL); - if (IS_ERR(ef)) - return ef; +static LLIST_HEAD(free_list); - mutex_lock(&eventfs_mutex); - list_add_tail(&ef->list, &ef_parent->ei->e_top_files); - ef->d_parent = ef_parent->dentry; - mutex_unlock(&eventfs_mutex); - return ef; -} - -/** - * eventfs_add_events_file - add the data needed to create a file for later reference - * @name: the name of the file to create. - * @mode: the permission that the file should have. - * @parent: parent dentry for this file. - * @data: something that the caller will want to get to later on. - * @fop: struct file_operations that should be used for this file. - * - * This function is used to add the information needed to create a - * dentry/inode within the top level events directory. The file created - * will have the @mode permissions. The @data will be used to fill the - * inode.i_private when the open() call is done. The dentry and inodes are - * all created when they are referenced, and removed when they are no - * longer referenced. - */ -int eventfs_add_events_file(const char *name, umode_t mode, - struct dentry *parent, void *data, - const struct file_operations *fop) +static void eventfs_workfn(struct work_struct *work) { - struct tracefs_inode *ti; - struct eventfs_inode *ei; - struct eventfs_file *ef; - - if (security_locked_down(LOCKDOWN_TRACEFS)) - return -ENODEV; - - if (!parent) - return -EINVAL; - - if (!(mode & S_IFMT)) - mode |= S_IFREG; - - if (!parent->d_inode) - return -EINVAL; - - ti = get_tracefs(parent->d_inode); - if (!(ti->flags & TRACEFS_EVENT_INODE)) - return -EINVAL; - - ei = ti->private; - ef = eventfs_prepare_ef(name, mode, fop, NULL, data); - - if (IS_ERR(ef)) - return -ENOMEM; - - mutex_lock(&eventfs_mutex); - list_add_tail(&ef->list, &ei->e_top_files); - ef->d_parent = parent; - mutex_unlock(&eventfs_mutex); - return 0; + struct eventfs_inode *ei, *tmp; + struct llist_node *llnode; + + llnode = llist_del_all(&free_list); + llist_for_each_entry_safe(ei, tmp, llnode, llist) { + /* This dput() matches the dget() from unhook_dentry() */ + for (int i = 0; i < ei->nr_entries; i++) { + if (ei->d_children[i]) + dput(ei->d_children[i]); + } + /* This should only get here if it had a dentry */ + if (!WARN_ON_ONCE(!ei->dentry)) + dput(ei->dentry); + } } -/** - * eventfs_add_file - add eventfs file to list to create later - * @name: the name of the file to create. - * @mode: the permission that the file should have. - * @ef_parent: parent eventfs_file for this file. - * @data: something that the caller will want to get to later on. - * @fop: struct file_operations that should be used for this file. - * - * This function is used to add the information needed to create a - * file within a subdirectory of the events directory. The file created - * will have the @mode permissions. The @data will be used to fill the - * inode.i_private when the open() call is done. The dentry and inodes are - * all created when they are referenced, and removed when they are no - * longer referenced. - */ -int eventfs_add_file(const char *name, umode_t mode, - struct eventfs_file *ef_parent, - void *data, - const struct file_operations *fop) -{ - struct eventfs_file *ef; - - if (security_locked_down(LOCKDOWN_TRACEFS)) - return -ENODEV; +static DECLARE_WORK(eventfs_work, eventfs_workfn); - if (!ef_parent) - return -EINVAL; +static void free_rcu_ei(struct rcu_head *head) +{ + struct eventfs_inode *ei = container_of(head, struct eventfs_inode, rcu); - if (!(mode & S_IFMT)) - mode |= S_IFREG; + if (ei->dentry) { + /* Do not free the ei until all references of dentry are gone */ + if (llist_add(&ei->llist, &free_list)) + queue_work(system_unbound_wq, &eventfs_work); + return; + } - ef = eventfs_prepare_ef(name, mode, fop, NULL, data); - if (IS_ERR(ef)) - return -ENOMEM; + /* If the ei doesn't have a dentry, neither should its children */ + for (int i = 0; i < ei->nr_entries; i++) { + WARN_ON_ONCE(ei->d_children[i]); + } - mutex_lock(&eventfs_mutex); - list_add_tail(&ef->list, &ef_parent->ei->e_top_files); - ef->d_parent = ef_parent->dentry; - mutex_unlock(&eventfs_mutex); - return 0; + free_ei(ei); } -static void free_ef(struct rcu_head *head) +static void unhook_dentry(struct dentry *dentry) { - struct eventfs_file *ef = container_of(head, struct eventfs_file, rcu); + if (!dentry) + return; + /* + * Need to add a reference to the dentry that is expected by + * simple_recursive_removal(), which will include a dput(). + */ + dget(dentry); - kfree(ef->name); - kfree(ef->ei); - kfree(ef); + /* + * Also add a reference for the dput() in eventfs_workfn(). + * That is required as that dput() will free the ei after + * the SRCU grace period is over. + */ + dget(dentry); } /** * eventfs_remove_rec - remove eventfs dir or file from list - * @ef: eventfs_file to be removed. - * @head: to create list of eventfs_file to be deleted - * @level: to check recursion depth + * @ei: eventfs_inode to be removed. + * @level: prevent recursion from going more than 3 levels deep. * - * The helper function eventfs_remove_rec() is used to clean up and free the - * associated data from eventfs for both of the added functions. + * This function recursively removes eventfs_inodes which + * contains info of files and/or directories. */ -static void eventfs_remove_rec(struct eventfs_file *ef, struct list_head *head, int level) +static void eventfs_remove_rec(struct eventfs_inode *ei, int level) { - struct eventfs_file *ef_child; + struct eventfs_inode *ei_child; - if (!ef) + if (!ei) return; /* * Check recursion depth. It should never be greater than 3: @@ -806,100 +1005,76 @@ static void eventfs_remove_rec(struct eventfs_file *ef, struct list_head *head, if (WARN_ON_ONCE(level > 3)) return; - if (ef->ei) { - /* search for nested folders or files */ - list_for_each_entry_srcu(ef_child, &ef->ei->e_top_files, list, - lockdep_is_held(&eventfs_mutex)) { - eventfs_remove_rec(ef_child, head, level + 1); + /* search for nested folders or files */ + list_for_each_entry_srcu(ei_child, &ei->children, list, + lockdep_is_held(&eventfs_mutex)) { + /* Children only have dentry if parent does */ + WARN_ON_ONCE(ei_child->dentry && !ei->dentry); + eventfs_remove_rec(ei_child, level + 1); + } + + + ei->is_freed = 1; + + for (int i = 0; i < ei->nr_entries; i++) { + if (ei->d_children[i]) { + /* Children only have dentry if parent does */ + WARN_ON_ONCE(!ei->dentry); + unhook_dentry(ei->d_children[i]); } } - list_del_rcu(&ef->list); - list_add_tail(&ef->del_list, head); + unhook_dentry(ei->dentry); + + list_del_rcu(&ei->list); + call_srcu(&eventfs_srcu, &ei->rcu, free_rcu_ei); } /** - * eventfs_remove - remove eventfs dir or file from list - * @ef: eventfs_file to be removed. + * eventfs_remove_dir - remove eventfs dir or file from list + * @ei: eventfs_inode to be removed. * * This function acquire the eventfs_mutex lock and call eventfs_remove_rec() */ -void eventfs_remove(struct eventfs_file *ef) +void eventfs_remove_dir(struct eventfs_inode *ei) { - struct eventfs_file *tmp; - LIST_HEAD(ef_del_list); - struct dentry *dentry_list = NULL; struct dentry *dentry; - if (!ef) + if (!ei) return; mutex_lock(&eventfs_mutex); - eventfs_remove_rec(ef, &ef_del_list, 0); - list_for_each_entry_safe(ef, tmp, &ef_del_list, del_list) { - if (ef->dentry) { - unsigned long ptr = (unsigned long)dentry_list; - - /* Keep the dentry from being freed yet */ - dget(ef->dentry); - - /* - * Paranoid: The dget() above should prevent the dentry - * from being freed and calling eventfs_set_ef_status_free(). - * But just in case, set the link list LSB pointer to 1 - * and have eventfs_set_ef_status_free() check that to - * make sure that if it does happen, it will not think - * the d_fsdata is an event_file. - * - * For this to work, no event_file should be allocated - * on a odd space, as the ef should always be allocated - * to be at least word aligned. Check for that too. - */ - WARN_ON_ONCE(ptr & 1); - - ef->dentry->d_fsdata = (void *)(ptr | 1); - dentry_list = ef->dentry; - ef->dentry = NULL; - } - call_srcu(&eventfs_srcu, &ef->rcu, free_ef); - } + dentry = ei->dentry; + eventfs_remove_rec(ei, 0); mutex_unlock(&eventfs_mutex); - while (dentry_list) { - unsigned long ptr; - - dentry = dentry_list; - ptr = (unsigned long)dentry->d_fsdata & ~1UL; - dentry_list = (struct dentry *)ptr; - dentry->d_fsdata = NULL; - d_invalidate(dentry); - mutex_lock(&eventfs_mutex); - /* dentry should now have at least a single reference */ - WARN_ONCE((int)d_count(dentry) < 1, - "dentry %p less than one reference (%d) after invalidate\n", - dentry, d_count(dentry)); - mutex_unlock(&eventfs_mutex); - dput(dentry); - } + /* + * If any of the ei children has a dentry, then the ei itself + * must have a dentry. + */ + if (dentry) + simple_recursive_removal(dentry, NULL); } /** - * eventfs_remove_events_dir - remove eventfs dir or file from list - * @dentry: events's dentry to be removed. + * eventfs_remove_events_dir - remove the top level eventfs directory + * @ei: the event_inode returned by eventfs_create_events_dir(). * - * This function remove events main directory + * This function removes the events main directory */ -void eventfs_remove_events_dir(struct dentry *dentry) +void eventfs_remove_events_dir(struct eventfs_inode *ei) { - struct tracefs_inode *ti; - - if (!dentry || !dentry->d_inode) - return; + struct dentry *dentry; - ti = get_tracefs(dentry->d_inode); - if (!ti || !(ti->flags & TRACEFS_EVENT_INODE)) - return; + dentry = ei->dentry; + eventfs_remove_dir(ei); - d_invalidate(dentry); + /* + * Matches the dget() done by tracefs_start_creating() + * in eventfs_create_events_dir() when it the dentry was + * created. In other words, it's a normal dentry that + * sticks around while the other ei->dentry are created + * and destroyed dynamically. + */ dput(dentry); } |