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authorDipankar Sarma <dipankar@in.ibm.com>2005-09-10 00:04:14 +0400
committerLinus Torvalds <torvalds@g5.osdl.org>2005-09-10 00:57:55 +0400
commitb835996f628eadb55c5fb222ba46fe9395bf73c7 (patch)
treed63d80585d197e1ffc299af4a0034049790fb197 /fs
parentab2af1f5005069321c5d130f09cce577b03f43ef (diff)
downloadlinux-b835996f628eadb55c5fb222ba46fe9395bf73c7.tar.xz
[PATCH] files: lock-free fd look-up
With the use of RCU in files structure, the look-up of files using fds can now be lock-free. The lookup is protected by rcu_read_lock()/rcu_read_unlock(). This patch changes the readers to use lock-free lookup. Signed-off-by: Maneesh Soni <maneesh@in.ibm.com> Signed-off-by: Ravikiran Thirumalai <kiran_th@gmail.com> 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')
-rw-r--r--fs/fcntl.c4
-rw-r--r--fs/proc/base.c29
-rw-r--r--fs/select.c13
3 files changed, 27 insertions, 19 deletions
diff --git a/fs/fcntl.c b/fs/fcntl.c
index d2f3ed8acd93..863b46e0d78a 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -40,10 +40,10 @@ static inline int get_close_on_exec(unsigned int fd)
struct files_struct *files = current->files;
struct fdtable *fdt;
int res;
- spin_lock(&files->file_lock);
+ rcu_read_lock();
fdt = files_fdtable(files);
res = FD_ISSET(fd, fdt->close_on_exec);
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
return res;
}
diff --git a/fs/proc/base.c b/fs/proc/base.c
index d0087a0b024b..23db452ab428 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -62,6 +62,7 @@
#include <linux/namespace.h>
#include <linux/mm.h>
#include <linux/smp_lock.h>
+#include <linux/rcupdate.h>
#include <linux/kallsyms.h>
#include <linux/mount.h>
#include <linux/security.h>
@@ -283,16 +284,16 @@ static int proc_fd_link(struct inode *inode, struct dentry **dentry, struct vfsm
files = get_files_struct(task);
if (files) {
- spin_lock(&files->file_lock);
+ rcu_read_lock();
file = fcheck_files(files, fd);
if (file) {
*mnt = mntget(file->f_vfsmnt);
*dentry = dget(file->f_dentry);
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
put_files_struct(files);
return 0;
}
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
put_files_struct(files);
}
return -ENOENT;
@@ -1062,7 +1063,7 @@ static int proc_readfd(struct file * filp, void * dirent, filldir_t filldir)
files = get_files_struct(p);
if (!files)
goto out;
- spin_lock(&files->file_lock);
+ rcu_read_lock();
fdt = files_fdtable(files);
for (fd = filp->f_pos-2;
fd < fdt->max_fds;
@@ -1071,7 +1072,7 @@ static int proc_readfd(struct file * filp, void * dirent, filldir_t filldir)
if (!fcheck_files(files, fd))
continue;
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
j = NUMBUF;
i = fd;
@@ -1083,12 +1084,12 @@ static int proc_readfd(struct file * filp, void * dirent, filldir_t filldir)
ino = fake_ino(tid, PROC_TID_FD_DIR + fd);
if (filldir(dirent, buf+j, NUMBUF-j, fd+2, ino, DT_LNK) < 0) {
- spin_lock(&files->file_lock);
+ rcu_read_lock();
break;
}
- spin_lock(&files->file_lock);
+ rcu_read_lock();
}
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
put_files_struct(files);
}
out:
@@ -1263,9 +1264,9 @@ static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)
files = get_files_struct(task);
if (files) {
- spin_lock(&files->file_lock);
+ rcu_read_lock();
if (fcheck_files(files, fd)) {
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
put_files_struct(files);
if (task_dumpable(task)) {
inode->i_uid = task->euid;
@@ -1277,7 +1278,7 @@ static int tid_fd_revalidate(struct dentry *dentry, struct nameidata *nd)
security_task_to_inode(task, inode);
return 1;
}
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
put_files_struct(files);
}
d_drop(dentry);
@@ -1369,7 +1370,7 @@ static struct dentry *proc_lookupfd(struct inode * dir, struct dentry * dentry,
if (!files)
goto out_unlock;
inode->i_mode = S_IFLNK;
- spin_lock(&files->file_lock);
+ rcu_read_lock();
file = fcheck_files(files, fd);
if (!file)
goto out_unlock2;
@@ -1377,7 +1378,7 @@ static struct dentry *proc_lookupfd(struct inode * dir, struct dentry * dentry,
inode->i_mode |= S_IRUSR | S_IXUSR;
if (file->f_mode & 2)
inode->i_mode |= S_IWUSR | S_IXUSR;
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
put_files_struct(files);
inode->i_op = &proc_pid_link_inode_operations;
inode->i_size = 64;
@@ -1387,7 +1388,7 @@ static struct dentry *proc_lookupfd(struct inode * dir, struct dentry * dentry,
return NULL;
out_unlock2:
- spin_unlock(&files->file_lock);
+ rcu_read_unlock();
put_files_struct(files);
out_unlock:
iput(inode);
diff --git a/fs/select.c b/fs/select.c
index 2e56325c73c4..f10a10317d54 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -22,6 +22,7 @@
#include <linux/personality.h> /* for STICKY_TIMEOUTS */
#include <linux/file.h>
#include <linux/fs.h>
+#include <linux/rcupdate.h>
#include <asm/uaccess.h>
@@ -185,9 +186,9 @@ int do_select(int n, fd_set_bits *fds, long *timeout)
int retval, i;
long __timeout = *timeout;
- spin_lock(&current->files->file_lock);
+ rcu_read_lock();
retval = max_select_fd(n, fds);
- spin_unlock(&current->files->file_lock);
+ rcu_read_unlock();
if (retval < 0)
return retval;
@@ -329,8 +330,10 @@ sys_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp, s
goto out_nofds;
/* max_fdset can increase, so grab it once to avoid race */
+ rcu_read_lock();
fdt = files_fdtable(current->files);
max_fdset = fdt->max_fdset;
+ rcu_read_unlock();
if (n > max_fdset)
n = max_fdset;
@@ -469,10 +472,14 @@ asmlinkage long sys_poll(struct pollfd __user * ufds, unsigned int nfds, long ti
struct poll_list *head;
struct poll_list *walk;
struct fdtable *fdt;
+ int max_fdset;
/* Do a sanity check on nfds ... */
+ rcu_read_lock();
fdt = files_fdtable(current->files);
- if (nfds > fdt->max_fdset && nfds > OPEN_MAX)
+ max_fdset = fdt->max_fdset;
+ rcu_read_unlock();
+ if (nfds > max_fdset && nfds > OPEN_MAX)
return -EINVAL;
if (timeout) {