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author | 2005-09-09 13:04:13 -0700 | |
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committer | 2005-09-09 13:57:55 -0700 | |
commit | ab2af1f5005069321c5d130f09cce577b03f43ef (patch) | |
tree | 73a70ba486f522cd9eeeef376ede2b5a1c1b473b /fs/open.c | |
parent | [PATCH] files-sparc64-fix 2 (diff) | |
download | linux-ab2af1f5005069321c5d130f09cce577b03f43ef.tar.gz linux-ab2af1f5005069321c5d130f09cce577b03f43ef.tar.bz2 linux-ab2af1f5005069321c5d130f09cce577b03f43ef.zip |
[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/open.c')
-rw-r--r-- | fs/open.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/fs/open.c b/fs/open.c index b6542516a0ca..2fac58c51910 100644 --- a/fs/open.c +++ b/fs/open.c @@ -24,6 +24,7 @@ #include <linux/personality.h> #include <linux/pagemap.h> #include <linux/syscalls.h> +#include <linux/rcupdate.h> #include <asm/unistd.h> @@ -930,9 +931,8 @@ void fastcall fd_install(unsigned int fd, struct file * file) struct fdtable *fdt; spin_lock(&files->file_lock); fdt = files_fdtable(files); - if (unlikely(fdt->fd[fd] != NULL)) - BUG(); - fdt->fd[fd] = file; + BUG_ON(fdt->fd[fd] != NULL); + rcu_assign_pointer(fdt->fd[fd], file); spin_unlock(&files->file_lock); } @@ -1024,7 +1024,7 @@ asmlinkage long sys_close(unsigned int fd) filp = fdt->fd[fd]; if (!filp) goto out_unlock; - fdt->fd[fd] = NULL; + rcu_assign_pointer(fdt->fd[fd], NULL); FD_CLR(fd, fdt->close_on_exec); __put_unused_fd(files, fd); spin_unlock(&files->file_lock); |