From: "Steven Rostedt (Google)" rostedt@goodmis.org
The eventfs creates dynamically allocated dentries and inodes. Using the dcache_readdir() logic for its own directory lookups requires hiding the cursor of the dcache logic and playing games to allow the dcache_readdir() to still have access to the cursor while the eventfs saved what it created and what it needs to release.
Instead, just have eventfs have its own iterate_shared callback function that will fill in the dent entries. This simplifies the code quite a bit.
Link: https://lore.kernel.org/linux-trace-kernel/20240104015435.682218477@goodmis....
Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: Mathieu Desnoyers mathieu.desnoyers@efficios.com Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Ajay Kaher akaher@vmware.com Cc: Al Viro viro@ZenIV.linux.org.uk Cc: Christian Brauner brauner@kernel.org Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org (cherry picked from commit 493ec81a8fb8e4ada6f223b8b73791a1280d4774) --- fs/tracefs/event_inode.c | 194 +++++++++++++-------------------------- 1 file changed, 64 insertions(+), 130 deletions(-)
diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index c360300fb866..41af56f44f0a 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -52,9 +52,7 @@ enum { 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) { @@ -148,11 +146,9 @@ 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, };
/* Return the evenfs_inode of the "events" directory */ @@ -643,128 +639,87 @@ static struct dentry *eventfs_root_lookup(struct inode *dir, 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; - - ti = get_tracefs(inode); - if (!(ti->flags & TRACEFS_EVENT_INODE)) - return -EINVAL; - - if (WARN_ON_ONCE(!dlist)) - return -EINVAL; - - for (i = 0; dlist->dentries && dlist->dentries[i]; i++) { - dput(dlist->dentries[i]); - } - - 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; -} - -/** - * 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; + struct dentry *ei_dentry = NULL; + struct dentry *dentry; + 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_dentry = READ_ONCE(ei->dentry); mutex_unlock(&eventfs_mutex);
- if (!ei) { - srcu_read_unlock(&eventfs_srcu, idx); - return -EINVAL; - } - - - data = ei->data; + if (!ei || !ei_dentry) + goto out;
- dlist = kmalloc(sizeof(*dlist), GFP_KERNEL); - if (!dlist) { - srcu_read_unlock(&eventfs_srcu, idx); - return -ENOMEM; - } + ret = 0;
- inode_lock(parent->d_inode); + /* + * Need to create the dentries and inodes to have a consistent + * inode number. + */ list_for_each_entry_srcu(ei_child, &ei->children, list, srcu_read_lock_held(&eventfs_srcu)) { - d = create_dir_dentry(ei, ei_child, parent); - if (d) { - ret = add_dentries(&dentries, d, cnt); - dput(d); - if (ret < 0) - break; - cnt++; + + if (c > 0) { + c--; + continue; } + + if (ei_child->is_freed) + continue; + + name = ei_child->name; + + dentry = create_dir_dentry(ei, ei_child, ei_dentry); + if (!dentry) + goto out; + ino = dentry->d_inode->i_ino; + dput(dentry); + + if (!dir_emit(ctx, name, strlen(name), ino, DT_DIR)) + goto out; + ctx->pos++; }
for (i = 0; i < ei->nr_entries; i++) { - void *cdata = data; + void *cdata = ei->data; + + if (c > 0) { + c--; + continue; + } + 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) @@ -774,42 +729,21 @@ static int dcache_dir_open_wrapper(struct inode *inode, struct file *file) mutex_unlock(&eventfs_mutex); if (r <= 0) continue; - d = create_file_dentry(ei, i, parent, name, mode, cdata, fops); - if (d) { - ret = add_dentries(&dentries, d, cnt); - dput(d); - if (ret < 0) - break; - cnt++; - } - } - inode_unlock(parent->d_inode); - 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; -} + dentry = create_file_dentry(ei, i, ei_dentry, name, mode, cdata, fops); + if (!dentry) + goto out; + ino = dentry->d_inode->i_ino; + dput(dentry);
-/* - * 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; + if (!dir_emit(ctx, name, strlen(name), ino, DT_REG)) + goto out; + ctx->pos++; + } + ret = 1; + out: + srcu_read_unlock(&eventfs_srcu, idx);
- file->private_data = dlist->cursor; - ret = dcache_readdir(file, ctx); - dlist->cursor = file->private_data; - file->private_data = dlist; return ret; }