diff options
author | Dipankar Sarma <dipankar@in.ibm.com> | 2005-09-10 00:04:13 +0400 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-09-10 00:57:55 +0400 |
commit | ab2af1f5005069321c5d130f09cce577b03f43ef (patch) | |
tree | 73a70ba486f522cd9eeeef376ede2b5a1c1b473b /fs/aio.c | |
parent | 6e72ad2c581de121cc7e772469e2a8f6b1fd4379 (diff) | |
download | linux-ab2af1f5005069321c5d130f09cce577b03f43ef.tar.xz |
[PATCH] files: files struct with RCU
Patch to eliminate struct files_struct.file_lock spinlock on the reader side
and use rcu refcounting rcuref_xxx api for the f_count refcounter. The
updates to the fdtable are done by allocating a new fdtable structure and
setting files->fdt to point to the new structure. The fdtable structure is
protected by RCU thereby allowing lock-free lookup. For fd arrays/sets that
are vmalloced, we use keventd to free them since RCU callbacks can't sleep. A
global list of fdtable to be freed is not scalable, so we use a per-cpu list.
If keventd is already handling the current cpu's work, we use a timer to defer
queueing of that work.
Since the last publication, this patch has been re-written to avoid using
explicit memory barriers and use rcu_assign_pointer(), rcu_dereference()
premitives instead. This required that the fd information is kept in a
separate structure (fdtable) and updated atomically.
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>
Diffstat (limited to 'fs/aio.c')
-rw-r--r-- | fs/aio.c | 3 |
1 files changed, 2 insertions, 1 deletions
@@ -29,6 +29,7 @@ #include <linux/highmem.h> #include <linux/workqueue.h> #include <linux/security.h> +#include <linux/rcuref.h> #include <asm/kmap_types.h> #include <asm/uaccess.h> @@ -499,7 +500,7 @@ static int __aio_put_req(struct kioctx *ctx, struct kiocb *req) /* Must be done under the lock to serialise against cancellation. * Call this aio_fput as it duplicates fput via the fput_work. */ - if (unlikely(atomic_dec_and_test(&req->ki_filp->f_count))) { + if (unlikely(rcuref_dec_and_test(&req->ki_filp->f_count))) { get_ioctx(ctx); spin_lock(&fput_lock); list_add(&req->ki_list, &fput_head); |