Skip to content
Commit d2fa4a84 authored by Mikhail Efremov's avatar Mikhail Efremov Committed by Al Viro
Browse files

vfs: Don't exchange "short" filenames unconditionally.

Only exchange source and destination filenames
if flags contain RENAME_EXCHANGE.
In case if executable file was running and replaced by
other file /proc/PID/exe should still show correct file name,
not the old name of the file by which it was replaced.

The scenario when this bug manifests itself was like this:
* ALT Linux uses rpm and start-stop-daemon;
* during a package upgrade rpm creates a temporary file
  for an executable to rename it upon successful unpacking;
* start-stop-daemon is run subsequently and it obtains
  the (nonexistant) temporary filename via /proc/PID/exe
  thus failing to identify the running process.

Note that "long" filenames (> DNAiME_INLINE_LEN) are still
exchanged without RENAME_EXCHANGE and this behaviour exists
long enough (should be fixed too apparently).
So this patch is just an interim workaround that restores
behavior for "short" names as it was before changes
introduced by commit da1ce067 ("vfs: add cross-rename").

See https://lkml.org/lkml/2014/9/7/6

 for details.

AV: the comments about being more careful with ->d_name.hash
than with ->d_name.name are from back in 2.3.40s; they
became obsolete by 2.3.60s, when we started to unhash the
target instead of swapping hash chain positions followed
by d_delete() as we used to do when dcache was first
introduced.

Acked-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: da1ce067 "vfs: add cross-rename"
Signed-off-by: default avatarMikhail Efremov <sem@altlinux.org>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent a28ddb87
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment