diff options
author | Dipankar Sarma <dipankar@in.ibm.com> | 2005-09-09 16:04:13 -0400 |
---|---|---|
committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-09-09 16:57:55 -0400 |
commit | ab2af1f5005069321c5d130f09cce577b03f43ef (patch) | |
tree | 73a70ba486f522cd9eeeef376ede2b5a1c1b473b /include/linux/fs.h | |
parent | 6e72ad2c581de121cc7e772469e2a8f6b1fd4379 (diff) |
[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 'include/linux/fs.h')
-rw-r--r-- | include/linux/fs.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index fd93ab7da90..7f61227827d 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h | |||
@@ -9,6 +9,7 @@ | |||
9 | #include <linux/config.h> | 9 | #include <linux/config.h> |
10 | #include <linux/limits.h> | 10 | #include <linux/limits.h> |
11 | #include <linux/ioctl.h> | 11 | #include <linux/ioctl.h> |
12 | #include <linux/rcuref.h> | ||
12 | 13 | ||
13 | /* | 14 | /* |
14 | * It's silly to have NR_OPEN bigger than NR_FILE, but you can change | 15 | * It's silly to have NR_OPEN bigger than NR_FILE, but you can change |
@@ -597,12 +598,13 @@ struct file { | |||
597 | spinlock_t f_ep_lock; | 598 | spinlock_t f_ep_lock; |
598 | #endif /* #ifdef CONFIG_EPOLL */ | 599 | #endif /* #ifdef CONFIG_EPOLL */ |
599 | struct address_space *f_mapping; | 600 | struct address_space *f_mapping; |
601 | struct rcu_head f_rcuhead; | ||
600 | }; | 602 | }; |
601 | extern spinlock_t files_lock; | 603 | extern spinlock_t files_lock; |
602 | #define file_list_lock() spin_lock(&files_lock); | 604 | #define file_list_lock() spin_lock(&files_lock); |
603 | #define file_list_unlock() spin_unlock(&files_lock); | 605 | #define file_list_unlock() spin_unlock(&files_lock); |
604 | 606 | ||
605 | #define get_file(x) atomic_inc(&(x)->f_count) | 607 | #define get_file(x) rcuref_inc(&(x)->f_count) |
606 | #define file_count(x) atomic_read(&(x)->f_count) | 608 | #define file_count(x) atomic_read(&(x)->f_count) |
607 | 609 | ||
608 | #define MAX_NON_LFS ((1UL<<31) - 1) | 610 | #define MAX_NON_LFS ((1UL<<31) - 1) |