diff options
Diffstat (limited to 'fs/tracefs/event_inode.c')
-rw-r--r-- | fs/tracefs/event_inode.c | 920 |
1 files changed, 359 insertions, 561 deletions
diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index 0b90869fd805..110e8a272189 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -32,6 +32,18 @@ */ static DEFINE_MUTEX(eventfs_mutex); +/* Choose something "unique" ;-) */ +#define EVENTFS_FILE_INODE_INO 0x12c4e37 + +/* Just try to make something consistent and unique */ +static int eventfs_dir_ino(struct eventfs_inode *ei) +{ + if (!ei->ino) + ei->ino = get_next_ino(); + + return ei->ino; +} + /* * 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). @@ -45,16 +57,55 @@ enum { EVENTFS_SAVE_MODE = BIT(16), EVENTFS_SAVE_UID = BIT(17), EVENTFS_SAVE_GID = BIT(18), + EVENTFS_TOPLEVEL = BIT(19), }; #define EVENTFS_MODE_MASK (EVENTFS_SAVE_MODE - 1) +/* + * eventfs_inode reference count management. + * + * NOTE! We count only references from dentries, in the + * form 'dentry->d_fsdata'. There are also references from + * directory inodes ('ti->private'), but the dentry reference + * count is always a superset of the inode reference count. + */ +static void release_ei(struct kref *ref) +{ + struct eventfs_inode *ei = container_of(ref, struct eventfs_inode, kref); + + WARN_ON_ONCE(!ei->is_freed); + + kfree(ei->entry_attrs); + kfree_const(ei->name); + kfree_rcu(ei, rcu); +} + +static inline void put_ei(struct eventfs_inode *ei) +{ + if (ei) + kref_put(&ei->kref, release_ei); +} + +static inline void free_ei(struct eventfs_inode *ei) +{ + if (ei) { + ei->is_freed = 1; + put_ei(ei); + } +} + +static inline struct eventfs_inode *get_ei(struct eventfs_inode *ei) +{ + if (ei) + kref_get(&ei->kref); + return ei; +} + static struct dentry *eventfs_root_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags); -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 int eventfs_iterate(struct file *file, struct dir_context *ctx); static void update_attr(struct eventfs_attr *attr, struct iattr *iattr) { @@ -94,7 +145,7 @@ static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry, /* 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, + ei->entry_attrs = kcalloc(ei->nr_entries, sizeof(*ei->entry_attrs), GFP_NOFS); if (!ei->entry_attrs) { ret = -ENOMEM; @@ -113,7 +164,21 @@ static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry, * determined by the parent directory. */ if (dentry->d_inode->i_mode & S_IFDIR) { - update_attr(&ei->attr, iattr); + /* + * The events directory dentry is never freed, unless its + * part of an instance that is deleted. It's attr is the + * default for its child files and directories. + * Do not update it. It's not used for its own mode or ownership. + */ + if (ei->is_events) { + /* But it still needs to know if it was modified */ + if (iattr->ia_valid & ATTR_UID) + ei->attr.mode |= EVENTFS_SAVE_UID; + if (iattr->ia_valid & ATTR_GID) + ei->attr.mode |= EVENTFS_SAVE_GID; + } else { + update_attr(&ei->attr, iattr); + } } else { name = dentry->d_name.name; @@ -131,9 +196,63 @@ static int eventfs_set_attr(struct mnt_idmap *idmap, struct dentry *dentry, return ret; } +static void update_top_events_attr(struct eventfs_inode *ei, struct super_block *sb) +{ + struct inode *root; + + /* Only update if the "events" was on the top level */ + if (!ei || !(ei->attr.mode & EVENTFS_TOPLEVEL)) + return; + + /* Get the tracefs root inode. */ + root = d_inode(sb->s_root); + ei->attr.uid = root->i_uid; + ei->attr.gid = root->i_gid; +} + +static void set_top_events_ownership(struct inode *inode) +{ + struct tracefs_inode *ti = get_tracefs(inode); + struct eventfs_inode *ei = ti->private; + + /* The top events directory doesn't get automatically updated */ + if (!ei || !ei->is_events || !(ei->attr.mode & EVENTFS_TOPLEVEL)) + return; + + update_top_events_attr(ei, inode->i_sb); + + if (!(ei->attr.mode & EVENTFS_SAVE_UID)) + inode->i_uid = ei->attr.uid; + + if (!(ei->attr.mode & EVENTFS_SAVE_GID)) + inode->i_gid = ei->attr.gid; +} + +static int eventfs_get_attr(struct mnt_idmap *idmap, + const struct path *path, struct kstat *stat, + u32 request_mask, unsigned int flags) +{ + struct dentry *dentry = path->dentry; + struct inode *inode = d_backing_inode(dentry); + + set_top_events_ownership(inode); + + generic_fillattr(idmap, request_mask, inode, stat); + return 0; +} + +static int eventfs_permission(struct mnt_idmap *idmap, + struct inode *inode, int mask) +{ + set_top_events_ownership(inode); + return generic_permission(idmap, inode, mask); +} + static const struct inode_operations eventfs_root_dir_inode_operations = { .lookup = eventfs_root_lookup, .setattr = eventfs_set_attr, + .getattr = eventfs_get_attr, + .permission = eventfs_permission, }; static const struct inode_operations eventfs_file_inode_operations = { @@ -141,24 +260,55 @@ static const struct inode_operations eventfs_file_inode_operations = { }; static const struct file_operations eventfs_file_operations = { - .open = dcache_dir_open_wrapper, .read = generic_read_dir, - .iterate_shared = dcache_readdir_wrapper, + .iterate_shared = eventfs_iterate, .llseek = generic_file_llseek, - .release = eventfs_release, }; -static void update_inode_attr(struct inode *inode, struct eventfs_attr *attr, umode_t mode) +/* Return the evenfs_inode of the "events" directory */ +static struct eventfs_inode *eventfs_find_events(struct dentry *dentry) { - if (!attr) { - inode->i_mode = mode; + struct eventfs_inode *ei; + + do { + // The parent is stable because we do not do renames + dentry = dentry->d_parent; + // ... and directories always have d_fsdata + ei = dentry->d_fsdata; + + /* + * If the ei is being freed, the ownership of the children + * doesn't matter. + */ + if (ei->is_freed) { + ei = NULL; + break; + } + // Walk upwards until you find the events inode + } while (!ei->is_events); + + update_top_events_attr(ei, dentry->d_sb); + + return ei; +} + +static void update_inode_attr(struct dentry *dentry, struct inode *inode, + struct eventfs_attr *attr, umode_t mode) +{ + struct eventfs_inode *events_ei = eventfs_find_events(dentry); + + if (!events_ei) + return; + + inode->i_mode = mode; + inode->i_uid = events_ei->attr.uid; + inode->i_gid = events_ei->attr.gid; + + if (!attr) 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; @@ -168,11 +318,10 @@ static void update_inode_attr(struct inode *inode, struct eventfs_attr *attr, um } /** - * create_file - create a file in the tracefs filesystem - * @name: the name of the file to create. + * lookup_file - look up a file in the tracefs filesystem + * @dentry: the dentry to look up * @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. * @@ -180,314 +329,137 @@ static void update_inode_attr(struct inode *inode, struct eventfs_attr *attr, um * 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, +static struct dentry *lookup_file(struct eventfs_inode *parent_ei, + struct dentry *dentry, + umode_t mode, struct eventfs_attr *attr, - struct dentry *parent, void *data, + void *data, const struct file_operations *fop) { 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; - - WARN_ON_ONCE(!parent); - dentry = eventfs_start_creating(name, parent); - - if (IS_ERR(dentry)) - return dentry; + return ERR_PTR(-EIO); inode = tracefs_get_inode(dentry->d_sb); if (unlikely(!inode)) - return eventfs_failed_creating(dentry); + return ERR_PTR(-ENOMEM); /* If the user updated the directory's attributes, use them */ - update_inode_attr(inode, attr, mode); + update_inode_attr(dentry, inode, attr, mode); inode->i_op = &eventfs_file_inode_operations; inode->i_fop = fop; inode->i_private = data; + /* All files will have the same inode number */ + inode->i_ino = EVENTFS_FILE_INODE_INO; + 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); + + // Files have their parent's ei as their fsdata + dentry->d_fsdata = get_ei(parent_ei); + + d_add(dentry, inode); + return NULL; }; /** - * create_dir - create a dir in the tracefs filesystem + * lookup_dir_entry - look up a dir in the tracefs filesystem + * @dentry: the directory to look up * @ei: the eventfs_inode that represents the directory to create - * @parent: parent dentry for this file. * - * This function will create a dentry for a directory represented by + * This function will look up a dentry for a directory represented by * a eventfs_inode. */ -static struct dentry *create_dir(struct eventfs_inode *ei, struct dentry *parent) +static struct dentry *lookup_dir_entry(struct dentry *dentry, + struct eventfs_inode *pei, struct eventfs_inode *ei) { struct tracefs_inode *ti; - struct dentry *dentry; struct inode *inode; - dentry = eventfs_start_creating(ei->name, parent); - if (IS_ERR(dentry)) - return dentry; - inode = tracefs_get_inode(dentry->d_sb); if (unlikely(!inode)) - return eventfs_failed_creating(dentry); + return ERR_PTR(-ENOMEM); /* If the user updated the directory's attributes, use them */ - update_inode_attr(inode, &ei->attr, S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO); + update_inode_attr(dentry, 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; + /* All directories will have the same inode number */ + inode->i_ino = eventfs_dir_ino(ei); + ti = get_tracefs(inode); ti->flags |= TRACEFS_EVENT_INODE; + /* Only directories have ti->private set to an ei, not files */ + ti->private = ei; - 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); + dentry->d_fsdata = get_ei(ei); + + d_add(dentry, inode); + return NULL; } -static void free_ei(struct eventfs_inode *ei) +static inline struct eventfs_inode *alloc_ei(const char *name) { - kfree_const(ei->name); - kfree(ei->d_children); - kfree(ei->entry_attrs); - kfree(ei); + struct eventfs_inode *ei = kzalloc(sizeof(*ei), GFP_KERNEL); + + if (!ei) + return NULL; + + ei->name = kstrdup_const(name, GFP_KERNEL); + if (!ei->name) { + kfree(ei); + return NULL; + } + kref_init(&ei->kref); + return ei; } /** - * eventfs_set_ei_status_free - remove the dentry reference from an eventfs_inode - * @ti: the tracefs_inode of the dentry + * eventfs_d_release - dentry is going away * @dentry: dentry which has the reference to remove. * * Remove the association between a dentry from an eventfs_inode. */ -void eventfs_set_ei_status_free(struct tracefs_inode *ti, struct dentry *dentry) +void eventfs_d_release(struct dentry *dentry) { - struct eventfs_inode *ei; - int i; - - mutex_lock(&eventfs_mutex); - - ei = dentry->d_fsdata; - if (!ei) - goto out; - - /* 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); + put_ei(dentry->d_fsdata); } /** - * create_file_dentry - create a dentry for a file of an eventfs_inode + * lookup_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 + * @idx: the index into the entry_attrs[] 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. + * address located at @e_dentry. */ 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) +lookup_file_dentry(struct dentry *dentry, + struct eventfs_inode *ei, int idx, + umode_t mode, void *data, + const struct file_operations *fops) { struct eventfs_attr *attr = NULL; - struct dentry **e_dentry = &ei->d_children[idx]; - struct dentry *dentry; - - WARN_ON_ONCE(!inode_is_locked(parent->d_inode)); - 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; - } - - /* ei->entry_attrs are protected by SRCU */ if (ei->entry_attrs) attr = &ei->entry_attrs[idx]; - mutex_unlock(&eventfs_mutex); - - dentry = create_file(name, mode, attr, parent, data, fops); - - mutex_lock(&eventfs_mutex); - - 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. - * - * If ei->is_freed is set, the e_dentry is currently on its - * way to being freed, don't return it. If e_dentry is NULL - * it means it was already freed. - */ - if (ei->is_freed) - dentry = NULL; - else - dentry = *e_dentry; - /* 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); - dentry = NULL; - } - mutex_unlock(&eventfs_mutex); - - if (lookup) - dput(dentry); - - return dentry; -} - -/** - * eventfs_post_create_dir - post create dir routine - * @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_inode *ei) -{ - 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(ei_child, &ei->children, list, - srcu_read_lock_held(&eventfs_srcu)) { - ei_child->d_parent = ei->dentry; - } - - ti = get_tracefs(ei->dentry->d_inode); - ti->private = ei; -} - -/** - * 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 - * - * This creates and attaches a directory dentry to the eventfs_inode @ei. - */ -static struct dentry * -create_dir_dentry(struct eventfs_inode *pei, struct eventfs_inode *ei, - struct dentry *parent, bool lookup) -{ - struct dentry *dentry = NULL; - - WARN_ON_ONCE(!inode_is_locked(parent->d_inode)); - - mutex_lock(&eventfs_mutex); - if (pei->is_freed || ei->is_freed) { - mutex_unlock(&eventfs_mutex); - return NULL; - } - 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); - return dentry; - } - mutex_unlock(&eventfs_mutex); - - dentry = create_dir(ei, parent); - - mutex_lock(&eventfs_mutex); - - 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. - * - * If ei->is_freed is set, the e_dentry is currently on its - * way to being freed. - */ - dentry = ei->dentry; - if (dentry && !lookup) - dget(dentry); - mutex_unlock(&eventfs_mutex); - return dentry; - } - - if (!ei->dentry && !ei->is_freed) { - ei->dentry = dentry; - eventfs_post_create_dir(ei); - 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); - dentry = NULL; - } - mutex_unlock(&eventfs_mutex); - - if (lookup) - dput(dentry); - - return dentry; + return lookup_file(ei, dentry, mode, attr, data, fops); } /** @@ -504,246 +476,153 @@ 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 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; + struct dentry *result = NULL; ti = get_tracefs(dir); if (!(ti->flags & TRACEFS_EVENT_INODE)) - return NULL; - - /* Grab srcu to prevent the ei from going away */ - idx = srcu_read_lock(&eventfs_srcu); + return ERR_PTR(-EIO); - /* - * 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) + ei = ti->private; + if (!ei || ei->is_freed) goto out; - data = ei->data; - - list_for_each_entry_srcu(ei_child, &ei->children, list, - srcu_read_lock_held(&eventfs_srcu)) { + list_for_each_entry(ei_child, &ei->children, list) { if (strcmp(ei_child->name, name) != 0) continue; - ret = simple_lookup(dir, dentry, flags); - create_dir_dentry(ei, ei_child, ei_dentry, true); - created = true; - break; - } - - if (created) + if (ei_child->is_freed) + goto out; + result = lookup_dir_entry(dentry, ei, ei_child); 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; -} -struct dentry_list { - void *cursor; - struct dentry **dentries; -}; - -/** - * eventfs_release - called to release eventfs file/dir - * @inode: inode to be released - * @file: file to be released (not used) - */ -static int eventfs_release(struct inode *inode, struct file *file) -{ - struct tracefs_inode *ti; - struct dentry_list *dlist = file->private_data; - void *cursor; - int i; + for (int i = 0; i < ei->nr_entries; i++) { + void *data; + umode_t mode; + const struct file_operations *fops; + const struct eventfs_entry *entry = &ei->entries[i]; - ti = get_tracefs(inode); - if (!(ti->flags & TRACEFS_EVENT_INODE)) - return -EINVAL; + if (strcmp(name, entry->name) != 0) + continue; - if (WARN_ON_ONCE(!dlist)) - return -EINVAL; + data = ei->data; + if (entry->callback(name, &mode, &data, &fops) <= 0) + goto out; - for (i = 0; dlist->dentries && dlist->dentries[i]; i++) { - dput(dlist->dentries[i]); + result = lookup_file_dentry(dentry, ei, i, mode, data, fops); + goto out; } - - cursor = dlist->cursor; - kfree(dlist->dentries); - kfree(dlist); - file->private_data = cursor; - 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_NOFS); - if (!tmp) - return -1; - tmp[cnt] = d; - tmp[cnt + 1] = NULL; - *dentries = tmp; - return 0; + out: + mutex_unlock(&eventfs_mutex); + return result; } -/** - * dcache_dir_open_wrapper - eventfs open wrapper - * @inode: not used - * @file: dir to be opened (to create it's children) - * - * Used to dynamic create file/dir with-in @file, all the - * file/dir will be created. If already created then references - * will be increased +/* + * Walk the children of a eventfs_inode to fill in getdents(). */ -static int dcache_dir_open_wrapper(struct inode *inode, struct file *file) +static int eventfs_iterate(struct file *file, struct dir_context *ctx) { const struct file_operations *fops; + struct inode *f_inode = file_inode(file); const struct eventfs_entry *entry; struct eventfs_inode *ei_child; struct tracefs_inode *ti; struct eventfs_inode *ei; - struct dentry_list *dlist; - struct dentry **dentries = NULL; - struct dentry *parent = file_dentry(file); - struct dentry *d; - struct inode *f_inode = file_inode(file); - const char *name = parent->d_name.name; + const char *name; umode_t mode; - void *data; - int cnt = 0; int idx; - int ret; - int i; - int r; + int ret = -EINVAL; + int ino; + int i, r, c; + + if (!dir_emit_dots(file, ctx)) + return 0; ti = get_tracefs(f_inode); if (!(ti->flags & TRACEFS_EVENT_INODE)) return -EINVAL; - if (WARN_ON_ONCE(file->private_data)) - return -EINVAL; + c = ctx->pos - 2; idx = srcu_read_lock(&eventfs_srcu); mutex_lock(&eventfs_mutex); ei = READ_ONCE(ti->private); + if (ei && ei->is_freed) + ei = NULL; mutex_unlock(&eventfs_mutex); - if (!ei) { - srcu_read_unlock(&eventfs_srcu, idx); - return -EINVAL; - } - - - data = ei->data; + if (!ei) + goto out; - dlist = kmalloc(sizeof(*dlist), GFP_KERNEL); - if (!dlist) { - srcu_read_unlock(&eventfs_srcu, idx); - return -ENOMEM; - } + /* + * Need to create the dentries and inodes to have a consistent + * inode number. + */ + ret = 0; - inode_lock(parent->d_inode); - list_for_each_entry_srcu(ei_child, &ei->children, list, - srcu_read_lock_held(&eventfs_srcu)) { - d = create_dir_dentry(ei, ei_child, parent, false); - if (d) { - ret = add_dentries(&dentries, d, cnt); - if (ret < 0) - break; - cnt++; - } - } + /* Start at 'c' to jump over already read entries */ + for (i = c; i < ei->nr_entries; i++, ctx->pos++) { + void *cdata = ei->data; - 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; + /* If ei->is_freed then just bail here, nothing more to do */ + if (ei->is_freed) { + mutex_unlock(&eventfs_mutex); + goto out; + } + r = entry->callback(name, &mode, &cdata, &fops); 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; - cnt++; + + ino = EVENTFS_FILE_INODE_INO; + + if (!dir_emit(ctx, name, strlen(name), ino, DT_REG)) + goto out; + } + + /* Subtract the skipped entries above */ + c -= min((unsigned int)c, (unsigned int)ei->nr_entries); + + list_for_each_entry_srcu(ei_child, &ei->children, list, + srcu_read_lock_held(&eventfs_srcu)) { + + if (c > 0) { + c--; + continue; } + + ctx->pos++; + + if (ei_child->is_freed) + continue; + + name = ei_child->name; + + ino = eventfs_dir_ino(ei_child); + + if (!dir_emit(ctx, name, strlen(name), ino, DT_DIR)) + goto out_dec; } - inode_unlock(parent->d_inode); + ret = 1; + out: srcu_read_unlock(&eventfs_srcu, idx); - ret = dcache_dir_open(inode, file); - /* - * dcache_dir_open() sets file->private_data to a dentry cursor. - * Need to save that but also save all the dentries that were - * opened by this function. - */ - dlist->cursor = file->private_data; - dlist->dentries = dentries; - file->private_data = dlist; return ret; -} - -/* - * This just sets the file->private_data back to the cursor and back. - */ -static int dcache_readdir_wrapper(struct file *file, struct dir_context *ctx) -{ - struct dentry_list *dlist = file->private_data; - int ret; - file->private_data = dlist->cursor; - ret = dcache_readdir(file, ctx); - dlist->cursor = file->private_data; - file->private_data = dlist; - return ret; + out_dec: + /* Incremented ctx->pos without adding something, reset it */ + ctx->pos--; + goto out; } /** @@ -790,25 +669,10 @@ struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode if (!parent) return ERR_PTR(-EINVAL); - ei = kzalloc(sizeof(*ei), GFP_KERNEL); + ei = alloc_ei(name); if (!ei) return ERR_PTR(-ENOMEM); - ei->name = kstrdup_const(name, GFP_KERNEL); - if (!ei->name) { - kfree(ei); - return ERR_PTR(-ENOMEM); - } - - 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); - } - } - ei->entries = entries; ei->nr_entries = size; ei->data = data; @@ -816,10 +680,8 @@ struct eventfs_inode *eventfs_create_dir(const char *name, struct eventfs_inode INIT_LIST_HEAD(&ei->list); mutex_lock(&eventfs_mutex); - if (!parent->is_freed) { + if (!parent->is_freed) list_add_tail(&ei->list, &parent->children); - ei->d_parent = parent->dentry; - } mutex_unlock(&eventfs_mutex); /* Was the parent freed? */ @@ -850,6 +712,8 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry struct eventfs_inode *ei; struct tracefs_inode *ti; struct inode *inode; + kuid_t uid; + kgid_t gid; if (security_locked_down(LOCKDOWN_TRACEFS)) return NULL; @@ -857,27 +721,36 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry if (IS_ERR(dentry)) return ERR_CAST(dentry); - ei = kzalloc(sizeof(*ei), GFP_KERNEL); + ei = alloc_ei(name); if (!ei) - goto fail_ei; + goto fail; inode = tracefs_get_inode(dentry->d_sb); if (unlikely(!inode)) goto fail; - if (size) { - ei->d_children = kzalloc(sizeof(*ei->d_children) * size, GFP_KERNEL); - if (!ei->d_children) - goto fail; - } - - ei->dentry = dentry; + // Note: we have a ref to the dentry from tracefs_start_creating() + ei->events_dir = dentry; ei->entries = entries; ei->nr_entries = size; + ei->is_events = 1; ei->data = data; - ei->name = kstrdup_const(name, GFP_KERNEL); - if (!ei->name) - goto fail; + + /* Save the ownership of this directory */ + uid = d_inode(dentry->d_parent)->i_uid; + gid = d_inode(dentry->d_parent)->i_gid; + + /* + * If the events directory is of the top instance, then parent + * is NULL. Set the attr.mode to reflect this and its permissions will + * default to the tracefs root dentry. + */ + if (!parent) + ei->attr.mode = EVENTFS_TOPLEVEL; + + /* This is used as the default ownership of the files and directories */ + ei->attr.uid = uid; + ei->attr.gid = gid; INIT_LIST_HEAD(&ei->children); INIT_LIST_HEAD(&ei->list); @@ -887,14 +760,24 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry ti->private = ei; inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; + inode->i_uid = uid; + inode->i_gid = gid; inode->i_op = &eventfs_root_dir_inode_operations; inode->i_fop = &eventfs_file_operations; - dentry->d_fsdata = ei; + dentry->d_fsdata = get_ei(ei); - /* directory inodes start off with i_nlink == 2 (for "." entry) */ - inc_nlink(inode); + /* + * Keep all eventfs directories with i_nlink == 1. + * Due to the dynamic nature of the dentry creations and not + * wanting to add a pointer to the parent eventfs_inode in the + * eventfs_inode structure, keeping the i_nlink in sync with the + * number of directories would cause too much complexity for + * something not worth much. Keeping directory links at 1 + * tells userspace not to trust the link number. + */ d_instantiate(dentry, inode); + /* The dentry of the "events" parent does keep track though */ inc_nlink(dentry->d_parent->d_inode); fsnotify_mkdir(dentry->d_parent->d_inode, dentry); tracefs_end_creating(dentry); @@ -902,72 +785,11 @@ struct eventfs_inode *eventfs_create_events_dir(const char *name, struct dentry return ei; fail: - kfree(ei->d_children); - kfree(ei); - fail_ei: + free_ei(ei); tracefs_failed_creating(dentry); return ERR_PTR(-ENOMEM); } -static LLIST_HEAD(free_list); - -static void eventfs_workfn(struct work_struct *work) -{ - 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); - } -} - -static DECLARE_WORK(eventfs_work, eventfs_workfn); - -static void free_rcu_ei(struct rcu_head *head) -{ - struct eventfs_inode *ei = container_of(head, struct eventfs_inode, rcu); - - 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; - } - - /* 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]); - } - - free_ei(ei); -} - -static void unhook_dentry(struct dentry *dentry) -{ - 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); - - /* - * 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 * @ei: eventfs_inode to be removed. @@ -980,8 +802,6 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, int level) { struct eventfs_inode *ei_child; - if (!ei) - return; /* * Check recursion depth. It should never be greater than 3: * 0 - events/ @@ -993,28 +813,11 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, int level) return; /* 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); + list_for_each_entry(ei_child, &ei->children, list) 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]); - } - } - - unhook_dentry(ei->dentry); - - list_del_rcu(&ei->list); - call_srcu(&eventfs_srcu, &ei->rcu, free_rcu_ei); + list_del(&ei->list); + free_ei(ei); } /** @@ -1025,22 +828,12 @@ static void eventfs_remove_rec(struct eventfs_inode *ei, int level) */ void eventfs_remove_dir(struct eventfs_inode *ei) { - struct dentry *dentry; - if (!ei) return; mutex_lock(&eventfs_mutex); - dentry = ei->dentry; eventfs_remove_rec(ei, 0); mutex_unlock(&eventfs_mutex); - - /* - * If any of the ei children has a dentry, then the ei itself - * must have a dentry. - */ - if (dentry) - simple_recursive_removal(dentry, NULL); } /** @@ -1053,7 +846,11 @@ void eventfs_remove_events_dir(struct eventfs_inode *ei) { struct dentry *dentry; - dentry = ei->dentry; + dentry = ei->events_dir; + if (!dentry) + return; + + ei->events_dir = NULL; eventfs_remove_dir(ei); /* @@ -1063,5 +860,6 @@ void eventfs_remove_events_dir(struct eventfs_inode *ei) * sticks around while the other ei->dentry are created * and destroyed dynamically. */ + d_invalidate(dentry); dput(dentry); } |