Here is a series of patches which introduce in total 13 new system calls
which take a file descriptor/filename pair instead of a single file
name. These functions, openat etc, have been discussed on numerous
occasions. They are needed to implement race-free filesystem traversal,
they are necessary to implement a virtual per-thread current working
directory (think multi-threaded backup software), etc.
We have in glibc today implementations of the interfaces which use the
/proc/self/fd magic. But this code is rather expensive. Here are some
results (similar to what Jim Meyering posted before).
The test creates a deep directory hierarchy on a tmpfs filesystem. Then
rm -fr is used to remove all directories. Without syscall support I get
this:
real 0m31.921s
user 0m0.688s
sys 0m31.234s
With syscall support the results are much better:
real 0m20.699s
user 0m0.536s
sys 0m20.149s
The interfaces are for obvious reasons currently not much used. But they'll
be used. coreutils (and Jeff's posixutils) are already using them.
Furthermore, code like ftw/fts in libc (maybe even glob) will also start using
them. I expect a patch to make follow soon. Every program which is walking
the filesystem tree will benefit.
Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@ftp.linux.org.uk>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Michael Kerrisk <mtk-manpages@gmx.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
With the new fdtable locking rules, you have to protect fdtable with either
->file_lock or rcu_read_lock/unlock(). There are some places where we
aren't doing either. This patch fixes those places.
Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Use schedule_timeout_interruptible() instead of
set_current_state()/schedule_timeout() to reduce kernel size.
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Richard Henderson <rth@twiddle.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
In order for the RCU to work, the file table array, sets and their sizes must
be updated atomically. Instead of ensuring this through too many memory
barriers, we put the arrays and their sizes in a separate structure. This
patch takes the first step of putting the file table elements in a separate
structure fdtable that is embedded withing files_struct. It also changes all
the users to refer to the file table using files_fdtable() macro. Subsequent
applciation of RCU becomes easier after this.
Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com>
Signed-Off-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Use helper functions to convert between timeval structure and jiffies
rather than custom logic.
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Domen Puncer <domen@coderock.org>
Acked-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
