On Mon 02-11-26 15:21:46, Christian Brauner wrote:
> proc_sys_readdir() counts the entries of a directory and resumes a
> listing at the number getdents64() stopped at. The entries are sorted
> by name, so one that is registered or unregistered in between shifts
> everything behind it by one. Listing /proc/sys/net/ipv4/conf with a
> buffer that holds ".", ".." and "all" and registering a device whose
> name sorts before "all" makes the next call return "all" a second time.
> Unregistering one that sorted before the position makes it skip an
> entry instead. So a listing that takes more than one call shows a name
> twice, or not at all. Even the 64k buffer of ls needs a second call to
> find the end of the directory, so a device that comes up right then
> repeats the last entry.
>
> So remember the name of the last entry a call emitted in the file and
> resume at the first usable entry after it, like kernfs resumes after
> the node it stopped at. The entry itself can't be pinned across calls,
> unregistering waits for that. If the position was moved by a seek in
> between the listing counts from the start like before, seeking to an
> arbitrary position has never been better than that.
>
> That also takes one walk down the tree to resume instead of a walk over
> every entry in front of the position with a round trip through
> sysctl_lock for each of them.
>
> Fixes: 77b14db502cb ("[PATCH] sysctl: reimplement the sysctl proc support")
> Cc: [email protected]
> Signed-off-by: Christian Brauner (Amutable) <[email protected]>
Just one coding style nit below. Otherwise feel free to add:
Reviewed-by: Jan Kara <[email protected]>
> + if (!name) {
> + after = rb_first(&dir->root);
> + } else for (node = dir->root.rb_node; node;) {
This indentation looks too inventive to me :) I'd just use
} else {
for (...) {
Honza
--
Jan Kara <[email protected]>
SUSE Labs, CR
