From: "Steven Rostedt (Google)" rostedt@goodmis.org
As the ei->entries array is fixed for the duration of the eventfs_inode, it can be used to skip over already read entries in eventfs_iterate().
That is, if ctx->pos is greater than zero, there's no reason in doing the loop across the ei->entries array for the entries less than ctx->pos. Instead, start the lookup of the entries at the current ctx->pos.
Link: https://lore.kernel.org/all/CAHk-=wiKwDUDv3+jCsv-uacDcHDVTYsXtBR9=6sGM5mqX+D... Link: https://lore.kernel.org/linux-trace-kernel/20240104220048.494956957@goodmis....
Cc: Masami Hiramatsu mhiramat@kernel.org Cc: Mark Rutland mark.rutland@arm.com Cc: Mathieu Desnoyers mathieu.desnoyers@efficios.com Cc: Andrew Morton akpm@linux-foundation.org Cc: Al Viro viro@zeniv.linux.org.uk Cc: Christian Brauner brauner@kernel.org Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Suggested-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org (cherry picked from commit 1de94b52d5e8d8b32f0252f14fad1f1edc2e71f1) --- fs/tracefs/event_inode.c | 23 ++++++++++------------- 1 file changed, 10 insertions(+), 13 deletions(-)
diff --git a/fs/tracefs/event_inode.c b/fs/tracefs/event_inode.c index a1934e0eea3b..fdff53d5a1f8 100644 --- a/fs/tracefs/event_inode.c +++ b/fs/tracefs/event_inode.c @@ -746,21 +746,15 @@ static int eventfs_iterate(struct file *file, struct dir_context *ctx) if (!ei || !ei_dentry) goto out;
- ret = 0; - /* * Need to create the dentries and inodes to have a consistent * inode number. */ - for (i = 0; i < ei->nr_entries; i++) { - void *cdata = ei->data; - - if (c > 0) { - c--; - continue; - } + ret = 0;
- ctx->pos++; + /* Start at 'c' to jump over already read entries */ + for (i = c; i < ei->nr_entries; i++, ctx->pos++) { + void *cdata = ei->data;
entry = &ei->entries[i]; name = entry->name; @@ -769,7 +763,7 @@ static int eventfs_iterate(struct file *file, struct dir_context *ctx) /* If ei->is_freed then just bail here, nothing more to do */ if (ei->is_freed) { mutex_unlock(&eventfs_mutex); - goto out_dec; + goto out; } r = entry->callback(name, &mode, &cdata, &fops); mutex_unlock(&eventfs_mutex); @@ -778,14 +772,17 @@ static int eventfs_iterate(struct file *file, struct dir_context *ctx)
dentry = create_file_dentry(ei, i, ei_dentry, name, mode, cdata, fops); if (!dentry) - goto out_dec; + goto out; ino = dentry->d_inode->i_ino; dput(dentry);
if (!dir_emit(ctx, name, strlen(name), ino, DT_REG)) - goto out_dec; + 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)) {