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eventfs: Shortcut eventfs_iterate() by skipping entries already read

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commit 1de94b52d5 upstream.

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+DhOg@mail.gmail.com/
Link: https://lore.kernel.org/linux-trace-kernel/20240104220048.494956957@goodmis.org

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Steven Rostedt (Google) 2024-02-06 07:09:46 -05:00 committed by Greg Kroah-Hartman
parent f3f41f444b
commit e638899f99
1 changed files with 10 additions and 13 deletions
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23
fs/tracefs/event_inode.c
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@ -746,22 +746,16 @@ 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++) {
ret = 0;
/* Start at 'c' to jump over already read entries */
for (i = c; i < ei->nr_entries; i++, ctx->pos++) {
void *cdata = ei->data;
if (c > 0) {
c--;
continue;
}
ctx->pos++;
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)) {