From: Stas Sergeev
> Sent: 22 April 2024 09:45
I seem to have 5 copies of this patch.....
> This patch moves the call to alloc_empty_file() below the call to
> path_init(). That changes is needed for the next patch, which adds
> a cred override for alloc_empty_file(). The needed cred info is only
> available after the call to path_init().
>
> No functional changes are intended by that patch.
...
> ---
> fs/namei.c | 26 +++++++++++++++++---------
> 1 file changed, 17 insertions(+), 9 deletions(-)
>
> diff --git a/fs/namei.c b/fs/namei.c
> index c5b2a25be7d0..2fde2c320ae9 100644
> --- a/fs/namei.c
> +++ b/fs/namei.c
> @@ -3782,22 +3782,30 @@ static struct file *path_openat(struct nameidata *nd,
> struct file *file;
> int error;
>
> - file = alloc_empty_file(op->open_flag, current_cred());
> - if (IS_ERR(file))
> - return file;
> -
> - if (unlikely(file->f_flags & __O_TMPFILE)) {
> + if (unlikely(op->open_flag & __O_TMPFILE)) {
> + file = alloc_empty_file(op->open_flag, current_cred());
> + if (IS_ERR(file))
> + return file;
> error = do_tmpfile(nd, flags, op, file);
> - } else if (unlikely(file->f_flags & O_PATH)) {
> + } else if (unlikely(op->open_flag & O_PATH)) {
> + file = alloc_empty_file(op->open_flag, current_cred());
> + if (IS_ERR(file))
> + return file;
> error = do_o_path(nd, flags, file);
You probably ought to merge the two 'unlikely' tests.
Otherwise there'll be two conditionals in the 'hot path'.
(There probably always were.)
So something like:
if (unlikely(op->open_flag & (__O_TMPFILE | O_PATH))) {
file = alloc_empty_file(op->open_flag, current_cred());
if (IS_ERR(file))
return file;
if (op->open_flag & __O_TMFILE)
error = do_tmpfile(nd, flags, op, file);
else
error = do_o_path(nd, flags, file);
} else {
Copying op->open_flag to a local may also generate better code.
David
> } else {
> const char *s = path_init(nd, flags);
> - while (!(error = link_path_walk(s, nd)) &&
> - (s = open_last_lookups(nd, file, op)) != NULL)
> - ;
> + file = alloc_empty_file(op->open_flag, current_cred());
> + error = PTR_ERR_OR_ZERO(file);
> + if (!error) {
> + while (!(error = link_path_walk(s, nd)) &&
> + (s = open_last_lookups(nd, file, op)) != NULL)
> + ;
> + }
> if (!error)
> error = do_open(nd, file, op);
> terminate_walk(nd);
> + if (IS_ERR(file))
> + return file;
> }
> if (likely(!error)) {
> if (likely(file->f_mode & FMODE_OPENED))
> --
> 2.44.0
>
-
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