[PATCH] files: break up files struct
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>
diff --git a/fs/exec.c b/fs/exec.c
index 222ab1c..14dd039 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -798,6 +798,7 @@
static inline void flush_old_files(struct files_struct * files)
{
long j = -1;
+ struct fdtable *fdt;
spin_lock(&files->file_lock);
for (;;) {
@@ -805,12 +806,13 @@
j++;
i = j * __NFDBITS;
- if (i >= files->max_fds || i >= files->max_fdset)
+ fdt = files_fdtable(files);
+ if (i >= fdt->max_fds || i >= fdt->max_fdset)
break;
- set = files->close_on_exec->fds_bits[j];
+ set = fdt->close_on_exec->fds_bits[j];
if (!set)
continue;
- files->close_on_exec->fds_bits[j] = 0;
+ fdt->close_on_exec->fds_bits[j] = 0;
spin_unlock(&files->file_lock);
for ( ; set ; i++,set >>= 1) {
if (set & 1) {
diff --git a/fs/fcntl.c b/fs/fcntl.c
index 6fbc9d8..bfecc62 100644
--- a/fs/fcntl.c
+++ b/fs/fcntl.c
@@ -24,20 +24,24 @@
void fastcall set_close_on_exec(unsigned int fd, int flag)
{
struct files_struct *files = current->files;
+ struct fdtable *fdt;
spin_lock(&files->file_lock);
+ fdt = files_fdtable(files);
if (flag)
- FD_SET(fd, files->close_on_exec);
+ FD_SET(fd, fdt->close_on_exec);
else
- FD_CLR(fd, files->close_on_exec);
+ FD_CLR(fd, fdt->close_on_exec);
spin_unlock(&files->file_lock);
}
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);
- res = FD_ISSET(fd, files->close_on_exec);
+ fdt = files_fdtable(files);
+ res = FD_ISSET(fd, fdt->close_on_exec);
spin_unlock(&files->file_lock);
return res;
}
@@ -54,24 +58,26 @@
unsigned int newfd;
unsigned int start;
int error;
+ struct fdtable *fdt;
error = -EINVAL;
if (orig_start >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
goto out;
+ fdt = files_fdtable(files);
repeat:
/*
* Someone might have closed fd's in the range
- * orig_start..files->next_fd
+ * orig_start..fdt->next_fd
*/
start = orig_start;
- if (start < files->next_fd)
- start = files->next_fd;
+ if (start < fdt->next_fd)
+ start = fdt->next_fd;
newfd = start;
- if (start < files->max_fdset) {
- newfd = find_next_zero_bit(files->open_fds->fds_bits,
- files->max_fdset, start);
+ if (start < fdt->max_fdset) {
+ newfd = find_next_zero_bit(fdt->open_fds->fds_bits,
+ fdt->max_fdset, start);
}
error = -EMFILE;
@@ -89,8 +95,8 @@
if (error)
goto repeat;
- if (start <= files->next_fd)
- files->next_fd = newfd + 1;
+ if (start <= fdt->next_fd)
+ fdt->next_fd = newfd + 1;
error = newfd;
@@ -101,13 +107,16 @@
static int dupfd(struct file *file, unsigned int start)
{
struct files_struct * files = current->files;
+ struct fdtable *fdt;
int fd;
spin_lock(&files->file_lock);
fd = locate_fd(files, file, start);
if (fd >= 0) {
- FD_SET(fd, files->open_fds);
- FD_CLR(fd, files->close_on_exec);
+ /* locate_fd() may have expanded fdtable, load the ptr */
+ fdt = files_fdtable(files);
+ FD_SET(fd, fdt->open_fds);
+ FD_CLR(fd, fdt->close_on_exec);
spin_unlock(&files->file_lock);
fd_install(fd, file);
} else {
@@ -123,6 +132,7 @@
int err = -EBADF;
struct file * file, *tofree;
struct files_struct * files = current->files;
+ struct fdtable *fdt;
spin_lock(&files->file_lock);
if (!(file = fcheck(oldfd)))
@@ -148,13 +158,14 @@
/* Yes. It's a race. In user space. Nothing sane to do */
err = -EBUSY;
- tofree = files->fd[newfd];
- if (!tofree && FD_ISSET(newfd, files->open_fds))
+ fdt = files_fdtable(files);
+ tofree = fdt->fd[newfd];
+ if (!tofree && FD_ISSET(newfd, fdt->open_fds))
goto out_fput;
- files->fd[newfd] = file;
- FD_SET(newfd, files->open_fds);
- FD_CLR(newfd, files->close_on_exec);
+ fdt->fd[newfd] = file;
+ FD_SET(newfd, fdt->open_fds);
+ FD_CLR(newfd, fdt->close_on_exec);
spin_unlock(&files->file_lock);
if (tofree)
diff --git a/fs/file.c b/fs/file.c
index 92b5f25..f5926ce 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -59,13 +59,15 @@
{
struct file **new_fds;
int error, nfds;
+ struct fdtable *fdt;
error = -EMFILE;
- if (files->max_fds >= NR_OPEN || nr >= NR_OPEN)
+ fdt = files_fdtable(files);
+ if (fdt->max_fds >= NR_OPEN || nr >= NR_OPEN)
goto out;
- nfds = files->max_fds;
+ nfds = fdt->max_fds;
spin_unlock(&files->file_lock);
/*
@@ -95,13 +97,14 @@
goto out;
/* Copy the existing array and install the new pointer */
+ fdt = files_fdtable(files);
- if (nfds > files->max_fds) {
+ if (nfds > fdt->max_fds) {
struct file **old_fds;
int i;
- old_fds = xchg(&files->fd, new_fds);
- i = xchg(&files->max_fds, nfds);
+ old_fds = xchg(&fdt->fd, new_fds);
+ i = xchg(&fdt->max_fds, nfds);
/* Don't copy/clear the array if we are creating a new
fd array for fork() */
@@ -164,12 +167,14 @@
{
fd_set *new_openset = NULL, *new_execset = NULL;
int error, nfds = 0;
+ struct fdtable *fdt;
error = -EMFILE;
- if (files->max_fdset >= NR_OPEN || nr >= NR_OPEN)
+ fdt = files_fdtable(files);
+ if (fdt->max_fdset >= NR_OPEN || nr >= NR_OPEN)
goto out;
- nfds = files->max_fdset;
+ nfds = fdt->max_fdset;
spin_unlock(&files->file_lock);
/* Expand to the max in easy steps */
@@ -193,24 +198,25 @@
error = 0;
/* Copy the existing tables and install the new pointers */
- if (nfds > files->max_fdset) {
- int i = files->max_fdset / (sizeof(unsigned long) * 8);
- int count = (nfds - files->max_fdset) / 8;
+ fdt = files_fdtable(files);
+ if (nfds > fdt->max_fdset) {
+ int i = fdt->max_fdset / (sizeof(unsigned long) * 8);
+ int count = (nfds - fdt->max_fdset) / 8;
/*
* Don't copy the entire array if the current fdset is
* not yet initialised.
*/
if (i) {
- memcpy (new_openset, files->open_fds, files->max_fdset/8);
- memcpy (new_execset, files->close_on_exec, files->max_fdset/8);
+ memcpy (new_openset, fdt->open_fds, fdt->max_fdset/8);
+ memcpy (new_execset, fdt->close_on_exec, fdt->max_fdset/8);
memset (&new_openset->fds_bits[i], 0, count);
memset (&new_execset->fds_bits[i], 0, count);
}
- nfds = xchg(&files->max_fdset, nfds);
- new_openset = xchg(&files->open_fds, new_openset);
- new_execset = xchg(&files->close_on_exec, new_execset);
+ nfds = xchg(&fdt->max_fdset, nfds);
+ new_openset = xchg(&fdt->open_fds, new_openset);
+ new_execset = xchg(&fdt->close_on_exec, new_execset);
spin_unlock(&files->file_lock);
free_fdset (new_openset, nfds);
free_fdset (new_execset, nfds);
@@ -237,13 +243,15 @@
int expand_files(struct files_struct *files, int nr)
{
int err, expand = 0;
+ struct fdtable *fdt;
- if (nr >= files->max_fdset) {
+ fdt = files_fdtable(files);
+ if (nr >= fdt->max_fdset) {
expand = 1;
if ((err = expand_fdset(files, nr)))
goto out;
}
- if (nr >= files->max_fds) {
+ if (nr >= fdt->max_fds) {
expand = 1;
if ((err = expand_fd_array(files, nr)))
goto out;
diff --git a/fs/locks.c b/fs/locks.c
index 11956b6..c2c09b4 100644
--- a/fs/locks.c
+++ b/fs/locks.c
@@ -2198,21 +2198,23 @@
{
struct files_struct *files = current->files;
int i, j;
+ struct fdtable *fdt;
if (from == files)
return;
lock_kernel();
j = 0;
+ fdt = files_fdtable(files);
for (;;) {
unsigned long set;
i = j * __NFDBITS;
- if (i >= files->max_fdset || i >= files->max_fds)
+ if (i >= fdt->max_fdset || i >= fdt->max_fds)
break;
- set = files->open_fds->fds_bits[j++];
+ set = fdt->open_fds->fds_bits[j++];
while (set) {
if (set & 1) {
- struct file *file = files->fd[i];
+ struct file *file = fdt->fd[i];
if (file)
__steal_locks(file, from);
}
diff --git a/fs/open.c b/fs/open.c
index 4ee2dcc..b654251 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -842,14 +842,16 @@
{
struct files_struct * files = current->files;
int fd, error;
+ struct fdtable *fdt;
error = -EMFILE;
spin_lock(&files->file_lock);
repeat:
- fd = find_next_zero_bit(files->open_fds->fds_bits,
- files->max_fdset,
- files->next_fd);
+ fdt = files_fdtable(files);
+ fd = find_next_zero_bit(fdt->open_fds->fds_bits,
+ fdt->max_fdset,
+ fdt->next_fd);
/*
* N.B. For clone tasks sharing a files structure, this test
@@ -872,14 +874,14 @@
goto repeat;
}
- FD_SET(fd, files->open_fds);
- FD_CLR(fd, files->close_on_exec);
- files->next_fd = fd + 1;
+ FD_SET(fd, fdt->open_fds);
+ FD_CLR(fd, fdt->close_on_exec);
+ fdt->next_fd = fd + 1;
#if 1
/* Sanity check */
- if (files->fd[fd] != NULL) {
+ if (fdt->fd[fd] != NULL) {
printk(KERN_WARNING "get_unused_fd: slot %d not NULL!\n", fd);
- files->fd[fd] = NULL;
+ fdt->fd[fd] = NULL;
}
#endif
error = fd;
@@ -893,9 +895,10 @@
static inline void __put_unused_fd(struct files_struct *files, unsigned int fd)
{
- __FD_CLR(fd, files->open_fds);
- if (fd < files->next_fd)
- files->next_fd = fd;
+ struct fdtable *fdt = files_fdtable(files);
+ __FD_CLR(fd, fdt->open_fds);
+ if (fd < fdt->next_fd)
+ fdt->next_fd = fd;
}
void fastcall put_unused_fd(unsigned int fd)
@@ -924,10 +927,12 @@
void fastcall fd_install(unsigned int fd, struct file * file)
{
struct files_struct *files = current->files;
+ struct fdtable *fdt;
spin_lock(&files->file_lock);
- if (unlikely(files->fd[fd] != NULL))
+ fdt = files_fdtable(files);
+ if (unlikely(fdt->fd[fd] != NULL))
BUG();
- files->fd[fd] = file;
+ fdt->fd[fd] = file;
spin_unlock(&files->file_lock);
}
@@ -1010,15 +1015,17 @@
{
struct file * filp;
struct files_struct *files = current->files;
+ struct fdtable *fdt;
spin_lock(&files->file_lock);
- if (fd >= files->max_fds)
+ fdt = files_fdtable(files);
+ if (fd >= fdt->max_fds)
goto out_unlock;
- filp = files->fd[fd];
+ filp = fdt->fd[fd];
if (!filp)
goto out_unlock;
- files->fd[fd] = NULL;
- FD_CLR(fd, files->close_on_exec);
+ fdt->fd[fd] = NULL;
+ FD_CLR(fd, fdt->close_on_exec);
__put_unused_fd(files, fd);
spin_unlock(&files->file_lock);
return filp_close(filp, files);
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 37668fe..d88d518 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -159,6 +159,7 @@
{
struct group_info *group_info;
int g;
+ struct fdtable *fdt = NULL;
read_lock(&tasklist_lock);
buffer += sprintf(buffer,
@@ -179,10 +180,12 @@
p->gid, p->egid, p->sgid, p->fsgid);
read_unlock(&tasklist_lock);
task_lock(p);
+ if (p->files)
+ fdt = files_fdtable(p->files);
buffer += sprintf(buffer,
"FDSize:\t%d\n"
"Groups:\t",
- p->files ? p->files->max_fds : 0);
+ fdt ? fdt->max_fds : 0);
group_info = p->group_info;
get_group_info(group_info);
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 84751f3..d0087a0 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1039,6 +1039,7 @@
int retval;
char buf[NUMBUF];
struct files_struct * files;
+ struct fdtable *fdt;
retval = -ENOENT;
if (!pid_alive(p))
@@ -1062,8 +1063,9 @@
if (!files)
goto out;
spin_lock(&files->file_lock);
+ fdt = files_fdtable(files);
for (fd = filp->f_pos-2;
- fd < files->max_fds;
+ fd < fdt->max_fds;
fd++, filp->f_pos++) {
unsigned int i,j;
diff --git a/fs/select.c b/fs/select.c
index b80e7eb..2e56325 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -132,11 +132,13 @@
unsigned long *open_fds;
unsigned long set;
int max;
+ struct fdtable *fdt;
/* handle last in-complete long-word first */
set = ~(~0UL << (n & (__NFDBITS-1)));
n /= __NFDBITS;
- open_fds = current->files->open_fds->fds_bits+n;
+ fdt = files_fdtable(current->files);
+ open_fds = fdt->open_fds->fds_bits+n;
max = 0;
if (set) {
set &= BITS(fds, n);
@@ -299,6 +301,7 @@
char *bits;
long timeout;
int ret, size, max_fdset;
+ struct fdtable *fdt;
timeout = MAX_SCHEDULE_TIMEOUT;
if (tvp) {
@@ -326,7 +329,8 @@
goto out_nofds;
/* max_fdset can increase, so grab it once to avoid race */
- max_fdset = current->files->max_fdset;
+ fdt = files_fdtable(current->files);
+ max_fdset = fdt->max_fdset;
if (n > max_fdset)
n = max_fdset;
@@ -464,9 +468,11 @@
unsigned int i;
struct poll_list *head;
struct poll_list *walk;
+ struct fdtable *fdt;
/* Do a sanity check on nfds ... */
- if (nfds > current->files->max_fdset && nfds > OPEN_MAX)
+ fdt = files_fdtable(current->files);
+ if (nfds > fdt->max_fdset && nfds > OPEN_MAX)
return -EINVAL;
if (timeout) {