[PATCH -mm 7/7][AIO] - Add listio syscall support

Sébastien Dugué
2007-02-01T09:40:14Z

From: Bharata B Rao <bharata@in.ibm.com>

This patch provides POSIX listio support by means of a new system call.

long lio_submit(aio_context_t ctx_id, int mode, long nr,
struct iocb __user * __user *iocbpp, struct sigevent __user *event)

This system call is similar to the io_submit() system call, but takes
two more arguments.

'mode' argument can be LIO_WAIT or LIO_NOWAIT.

'event' argument specifies the signal notification mechanism.

This patch is built on support provided by the aio signal notification
patch by Sebastien. The following two structures together provide
the support for grouping iocbs belonging to a list (lio).

struct aio_notify {
struct task_struct *target;
__u16 signo;
__u16 notify;
sigval_t value;
struct sigqueue *sigq;
};

struct lio_event {
atomic_t lio_users;
struct aio_notify lio_notify;
};

A single lio_event struct is maintained for the list of iocbs.
lio_users holds the number of requests attached to this lio and lio_notify
has the necessary information for generating completion notification
signal.

If the mode is LIO_WAIT, the event argument is ignored and the system
call waits until all the requests of the lio are completed.

If the mode is LIO_NOWAIT, the system call returns immediately after
submitting the io requests and may optionally notify the process on
list io completion depending on the event argument.

Signed-off-by: Sébastien Dugué <sebastien.dugue@bull.net>
Signed-off-by: Laurent Vivier <laurent.vivier@bull.net>
Signed-off-by: Bharata B Rao <bharata@in.ibm.com>
---

arch/i386/kernel/syscall_table.S | 1
arch/x86_64/ia32/ia32entry.S | 5 -
fs/aio.c | 193 ++++++++++++++++++++++++++++++++++-----
fs/compat.c | 125 +++++++++++++++++++++----
include/asm-i386/unistd.h | 3
include/asm-x86_64/unistd.h | 4
include/linux/aio.h | 14 ++
include/linux/aio_abi.h | 5 +
include/linux/syscalls.h | 2
9 files changed, 307 insertions(+), 45 deletions(-)

Index: linux-2.6.20-rc6-mm3/arch/i386/kernel/syscall_table.S
===================================================================
--- linux-2.6.20-rc6-mm3.orig/arch/i386/kernel/syscall_table.S 2007-01-31 15:31:59.000000000 +0100
+++ linux-2.6.20-rc6-mm3/arch/i386/kernel/syscall_table.S 2007-01-31 15:58:55.000000000 +0100
@@ -320,3 +320,4 @@ ENTRY(sys_call_table)
.long sys_getcpu
.long sys_epoll_pwait
.long sys_lutimesat /* 320 */
+ .long sys_lio_submit
Index: linux-2.6.20-rc6-mm3/arch/x86_64/ia32/ia32entry.S
===================================================================
--- linux-2.6.20-rc6-mm3.orig/arch/x86_64/ia32/ia32entry.S 2007-01-31 15:31:59.000000000 +0100
+++ linux-2.6.20-rc6-mm3/arch/x86_64/ia32/ia32entry.S 2007-01-31 15:58:55.000000000 +0100
@@ -714,8 +714,11 @@ ia32_sys_call_table:
.quad compat_sys_get_robust_list
.quad sys_splice
.quad sys_sync_file_range
- .quad sys_tee
+ .quad sys_tee /* 315 */
.quad compat_sys_vmsplice
.quad compat_sys_move_pages
.quad sys_getcpu
+ .quad quiet_ni_syscall /* sys_epoll_wait */
+ .quad quiet_ni_syscall /* 320: sys_lutimesat */
+ .quad compat_sys_lio_submit
ia32_syscall_end:
Index: linux-2.6.20-rc6-mm3/fs/aio.c
===================================================================
--- linux-2.6.20-rc6-mm3.orig/fs/aio.c 2007-01-31 15:31:59.000000000 +0100
+++ linux-2.6.20-rc6-mm3/fs/aio.c 2007-01-31 16:00:57.000000000 +0100
@@ -416,6 +416,7 @@ static struct kiocb fastcall *__aio_get_
req->ki_ctx = ctx;
req->ki_cancel = NULL;
req->ki_retry = NULL;
+ req->ki_lio = NULL;
req->ki_dtor = NULL;
req->private = NULL;
req->ki_iovec = NULL;
@@ -995,6 +996,72 @@ out_unlock:
return -EINVAL;
}

+/*
+ * lio_notify
+ * When all iocbs belonging to an lio are complete, this initiates
+ * the completion notification for the lio.
+ *
+ * NOTE: lio is freed here after the last iocb completes, but only
+ * for LIO_NOWAIT case. In case of LIO_WAIT, the submitting thread
+ * waits for iocbs to complete and later frees the lio.
+ */
+void lio_notify(struct lio_event *lio)
+{
+ int ret;
+
+ ret = atomic_dec_and_test(&lio->lio_users);
+
+ if (unlikely(ret) && lio->lio_notify.notify != SIGEV_NONE) {
+ /* last one -> notify process */
+ if (aio_send_signal(&lio->lio_notify))
+ __sigqueue_free(lio->lio_notify.sigq);
+ kfree(lio);
+ }
+}
+
+/*
+ * lio_create
+ * Allocates a lio_event structure which groups the iocbs belonging
+ * to the lio and sets up the completion notification.
+ *
+ * Case 1: LIO_NOWAIT and NULL sigevent - No need to group the iocbs
+ * and hence lio_event is not created.
+ * Case 2: LIO_NOWAIT and sigvent - lio_event is created and notification
+ * mechanism is setup.
+ * Case 3: LIO_WAIT - lio_event is created and sigevent is ignored.
+ */
+struct lio_event *lio_create(struct sigevent __user *user_event,
+ int mode)
+{
+ int ret = 0;
+ struct lio_event *lio = NULL;
+
+ if (unlikely((mode == LIO_NOWAIT) && !user_event))
+ return lio;
+
+ lio = kzalloc(sizeof(*lio), GFP_KERNEL);
+
+ if (!lio)
+ return ERR_PTR(-EAGAIN);
+
+ /*
+ * Grab an initial ref on the lio to avoid races between
+ * submission and completion.
+ */
+ atomic_set(&lio->lio_users, 1);
+
+ lio->lio_notify.notify = SIGEV_NONE;
+
+ if (user_event && (mode == LIO_NOWAIT)) {
+ ret = aio_setup_sigevent(&lio->lio_notify, user_event);
+ if (ret) {
+ kfree(lio);
+ return ERR_PTR(ret);
+ }
+ }
+ return lio;
+}
+
/* aio_complete
* Called when the io request on the given iocb is complete.
* Returns true if this is the last user of the request. The
@@ -1043,6 +1110,9 @@ int fastcall aio_complete(struct kiocb *
* when the event got cancelled.
*/
if (kiocbIsCancelled(iocb)) {
+ if (iocb->ki_lio)
+ lio_notify(iocb->ki_lio);
+
if (iocb->ki_notify.sigq)
__sigqueue_free(iocb->ki_notify.sigq);
goto put_rq;
@@ -1085,6 +1155,8 @@ int fastcall aio_complete(struct kiocb *
__sigqueue_free(iocb->ki_notify.sigq);
}

+ if (iocb->ki_lio)
+ lio_notify(iocb->ki_lio);
put_rq:
/* everything turned out well, dispose of the aiocb. */
ret = __aio_put_req(ctx, iocb);
@@ -1629,7 +1701,7 @@ static int aio_wake_function(wait_queue_
}

int fastcall io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
- struct iocb *iocb)
+ struct iocb *iocb, struct lio_event *lio)
{
struct kiocb *req;
struct file *file;
@@ -1690,6 +1762,9 @@ int fastcall io_submit_one(struct kioctx
goto out_put_req;
}

+ /* Attach this iocb to its lio */
+ req->ki_lio = lio;
+
ret = aio_setup_iocb(req);

if (ret)
@@ -1717,6 +1792,48 @@ out_put_req:
return ret;
}

+static int io_submit_group(struct kioctx *ctx, long nr,
+ struct iocb __user * __user *iocbpp, struct lio_event *lio)
+{
+ int i;
+ long ret = 0;
+
+ /*
+ * AKPM: should this return a partial result if some of the IOs were
+ * successfully submitted?
+ */
+ for (i = 0; i < nr; i++) {
+ struct iocb __user *user_iocb;
+ struct iocb tmp;
+
+ if (unlikely(__get_user(user_iocb, iocbpp + i))) {
+ ret = -EFAULT;
+ break;
+ }
+
+ if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
+ ret = -EFAULT;
+ break;
+ }
+
+ if (lio)
+ atomic_inc(&lio->lio_users);
+
+ ret = io_submit_one(ctx, user_iocb, &tmp, lio);
+ if (ret) {
+ if (lio) {
+ /*
+ * In case of listio, continue with
+ * the subsequent requests
+ */
+ atomic_dec(&lio->lio_users);
+ } else
+ break;
+ }
+ }
+ return i ? i : ret;
+}
+
/* sys_io_submit:
* Queue the nr iocbs pointed to by iocbpp for processing. Returns
* the number of iocbs queued. May return -EINVAL if the aio_context
@@ -1734,7 +1851,6 @@ asmlinkage long sys_io_submit(aio_contex
{
struct kioctx *ctx;
long ret = 0;
- int i;

if (unlikely((nr*sizeof(*iocbpp)) < 0))
return -EINVAL;
@@ -1748,31 +1864,61 @@ asmlinkage long sys_io_submit(aio_contex
return -EINVAL;
}

- /*
- * AKPM: should this return a partial result if some of the IOs were
- * successfully submitted?
- */
- for (i=0; i<nr; i++) {
- struct iocb __user *user_iocb;
- struct iocb tmp;
+ ret = io_submit_group(ctx, nr, iocbpp, NULL);

- if (unlikely(__get_user(user_iocb, iocbpp + i))) {
- ret = -EFAULT;
- break;
- }
+ put_ioctx(ctx);
+ return ret;
+}

- if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
- ret = -EFAULT;
- break;
- }
+asmlinkage long sys_lio_submit(aio_context_t ctx_id, int mode, long nr,
+ struct iocb __user * __user *iocbpp, struct sigevent __user *event)
+{
+ struct kioctx *ctx;
+ struct lio_event *lio = NULL;
+ long ret = 0;

- ret = io_submit_one(ctx, user_iocb, &tmp);
- if (ret)
- break;
+ if (unlikely((nr*sizeof(*iocbpp)) < 0))
+ return -EINVAL;
+
+ if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp)))))
+ return -EFAULT;
+
+ ctx = lookup_ioctx(ctx_id);
+ if (unlikely(!ctx)) {
+ pr_debug("EINVAL: lio_submit: invalid context id\n");
+ return -EINVAL;
+ }
+
+ lio = lio_create(event, mode);
+
+ ret = PTR_ERR(lio);
+ if (IS_ERR(lio))
+ goto out_put_ctx;
+
+ ret = io_submit_group(ctx, nr, iocbpp, lio);
+
+ /* If we failed to submit even one request just return */
+ if (ret < 0 ) {
+ if (lio)
+ kfree(lio);
+ goto out_put_ctx;
+ }
+
+ /*
+ * Drop extra ref on the lio now that we're done submitting requests.
+ */
+ if (lio)
+ lio_notify(lio);
+
+ if (mode == LIO_WAIT) {
+ wait_event(ctx->wait, atomic_read(&lio->lio_users) == 0);
+ kfree(lio);
}

+out_put_ctx:
put_ioctx(ctx);
- return i ? i : ret;
+
+ return ret;
}

/* lookup_kiocb
Index: linux-2.6.20-rc6-mm3/fs/compat.c
===================================================================
--- linux-2.6.20-rc6-mm3.orig/fs/compat.c 2007-01-31 15:31:59.000000000 +0100
+++ linux-2.6.20-rc6-mm3/fs/compat.c 2007-01-31 16:03:02.000000000 +0100
@@ -644,24 +644,13 @@ out:
return ret;
}

-asmlinkage long
-compat_sys_io_submit(aio_context_t ctx_id, int nr, u32 __user *iocb)
+static int compat_io_submit_group(struct kioctx *ctx, long nr,
+ u32 __user *iocb, struct lio_event *lio)
{
- struct kioctx *ctx;
- long ret = 0;
int i;
+ long ret = 0;

- if (unlikely((nr * sizeof(u32)) < 0))
- return -EINVAL;
-
- if (unlikely(!access_ok(VERIFY_READ, iocb, (nr * sizeof(u32)))))
- return -EFAULT;
-
- ctx = lookup_ioctx(ctx_id);
- if (unlikely(!ctx))
- return -EINVAL;
-
- for (i=0; i<nr; i++) {
+ for (i = 0; i < nr; i++) {
compat_uptr_t uptr;
struct iocb __user *user_iocb;
struct iocb tmp;
@@ -696,13 +685,105 @@ compat_sys_io_submit(aio_context_t ctx_i
tmp.aio_sigeventp = (__u64)event;
}

- ret = io_submit_one(ctx, user_iocb, &tmp);
- if (ret)
- break;
+ if (lio)
+ atomic_inc(&lio->lio_users);
+
+ ret = io_submit_one(ctx, user_iocb, &tmp, lio);
+ if (ret) {
+ if (lio) {
+ /*
+ * In case of listio, continue with
+ * the subsequent requests
+ */
+ atomic_dec(&lio->lio_users);
+ } else
+ break;
+ }
+
+
}
+ return i ? i : ret;
+}

+asmlinkage long
+compat_sys_io_submit(aio_context_t ctx_id, int nr, u32 __user *iocb)
+{
+ struct kioctx *ctx;
+ long ret = 0;
+
+ if (unlikely((nr*sizeof(u32)) < 0))
+ return -EINVAL;
+
+ if (unlikely(!access_ok(VERIFY_READ, iocb, (nr * sizeof(u32)))))
+ return -EFAULT;
+
+ ctx = lookup_ioctx(ctx_id);
+ if (unlikely(!ctx))
+ return -EINVAL;
+
+ ret = compat_io_submit_group(ctx, nr, iocb, NULL);
put_ioctx(ctx);
- return i ? i: ret;
+ return ret;
+}
+
+asmlinkage long
+compat_sys_lio_submit(aio_context_t ctx_id, int mode, int nr, u32 __user *iocb,
+ struct compat_sigevent __user *sig_user)
+{
+ struct kioctx *ctx;
+ struct lio_event *lio = NULL;
+ struct sigevent __user *event = NULL;
+ long ret = 0;
+
+ if (unlikely((nr*sizeof(u32)) < 0))
+ return -EINVAL;
+
+ if (unlikely(!access_ok(VERIFY_READ, iocb, (nr * sizeof(u32)))))
+ return -EFAULT;
+
+ ctx = lookup_ioctx(ctx_id);
+ if (unlikely(!ctx))
+ return -EINVAL;
+
+ if (sig_user) {
+ struct sigevent kevent;
+ event = compat_alloc_user_space(sizeof(struct sigevent));
+ if (get_compat_sigevent(&kevent, sig_user) ||
+ copy_to_user(event, &kevent, sizeof(struct sigevent))) {
+ ret = -EFAULT;
+ goto out_put_ctx;
+ }
+ }
+
+ lio = lio_create(event, mode);
+
+ ret = PTR_ERR(lio);
+ if (IS_ERR(lio))
+ goto out_put_ctx;
+
+ ret = compat_io_submit_group(ctx, nr, iocb, lio);
+
+ /* If we failed to submit even one request just return */
+ if (ret < 0) {
+ if (lio)
+ kfree(lio);
+ goto out_put_ctx;
+ }
+
+ /*
+ * Drop extra ref on the lio now that we're done submitting requests.
+ */
+ if (lio)
+ lio_notify(lio);
+
+ if (mode == LIO_WAIT) {
+ wait_event(ctx->wait, atomic_read(&lio->lio_users) == 0);
+ kfree(lio);
+ }
+
+out_put_ctx:
+ put_ioctx(ctx);
+ return ret;
}

struct compat_ncp_mount_data {
Index: linux-2.6.20-rc6-mm3/include/asm-i386/unistd.h
===================================================================
--- linux-2.6.20-rc6-mm3.orig/include/asm-i386/unistd.h 2007-01-31 15:31:59.000000000 +0100
+++ linux-2.6.20-rc6-mm3/include/asm-i386/unistd.h 2007-01-31 15:58:55.000000000 +0100
@@ -326,10 +326,11 @@
#define __NR_getcpu 318
#define __NR_epoll_pwait 319
#define __NR_lutimesat 320
+#define __NR_lio_submit 321

#ifdef __KERNEL__

-#define NR_syscalls 321
+#define NR_syscalls 322

#define __ARCH_WANT_IPC_PARSE_VERSION
#define __ARCH_WANT_OLD_READDIR
Index: linux-2.6.20-rc6-mm3/include/asm-x86_64/unistd.h
===================================================================
--- linux-2.6.20-rc6-mm3.orig/include/asm-x86_64/unistd.h 2007-01-31 15:31:59.000000000 +0100
+++ linux-2.6.20-rc6-mm3/include/asm-x86_64/unistd.h 2007-01-31 15:58:55.000000000 +0100
@@ -619,8 +619,10 @@ __SYSCALL(__NR_sync_file_range, sys_sync
__SYSCALL(__NR_vmsplice, sys_vmsplice)
#define __NR_move_pages 279
__SYSCALL(__NR_move_pages, sys_move_pages)
+#define __NR_lio_submit 280
+__SYSCALL(__NR_lio_submit, sys_lio_submit)

-#define __NR_syscall_max __NR_move_pages
+#define __NR_syscall_max __NR_lio_submit

#ifndef __NO_STUBS
#define __ARCH_WANT_OLD_READDIR
Index: linux-2.6.20-rc6-mm3/include/linux/aio_abi.h
===================================================================
--- linux-2.6.20-rc6-mm3.orig/include/linux/aio_abi.h 2007-01-31 15:31:59.000000000 +0100
+++ linux-2.6.20-rc6-mm3/include/linux/aio_abi.h 2007-01-31 15:58:55.000000000 +0100
@@ -45,6 +45,11 @@ enum {
IOCB_CMD_PWRITEV = 8,
};

+enum {
+ LIO_WAIT = 0,
+ LIO_NOWAIT = 1,
+};
+
/* read() from /dev/aio returns these structures. */
struct io_event {
__u64 data; /* the data field from the iocb */
Index: linux-2.6.20-rc6-mm3/include/linux/aio.h
===================================================================
--- linux-2.6.20-rc6-mm3.orig/include/linux/aio.h 2007-01-31 15:31:59.000000000 +0100
+++ linux-2.6.20-rc6-mm3/include/linux/aio.h 2007-01-31 15:58:55.000000000 +0100
@@ -63,6 +63,11 @@ struct aio_notify {
struct sigqueue *sigq;
};

+struct lio_event {
+ atomic_t lio_users;
+ struct aio_notify lio_notify;
+};
+
/* is there a better place to document function pointer methods? */
/**
* ki_retry - iocb forward progress callback
@@ -117,6 +122,8 @@ struct kiocb {
__u64 ki_user_data; /* user's data for completion */
struct wait_bit_queue ki_wait;
loff_t ki_pos;
+ /* lio this iocb might be attached to */
+ struct lio_event *ki_lio;

atomic_t ki_bio_count; /* num bio used for this iocb */
void *private;
@@ -225,12 +232,15 @@ struct mm_struct;
extern void FASTCALL(exit_aio(struct mm_struct *mm));
extern struct kioctx *lookup_ioctx(unsigned long ctx_id);
extern int FASTCALL(io_submit_one(struct kioctx *ctx,
- struct iocb __user *user_iocb, struct iocb *iocb));
+ struct iocb __user *user_iocb, struct iocb *iocb,
+ struct lio_event *lio));
+struct lio_event *lio_create(struct sigevent __user *user_event, int mode);
+void lio_notify(struct lio_event *lio);

/* semi private, but used by the 32bit emulations: */
struct kioctx *lookup_ioctx(unsigned long ctx_id);
int FASTCALL(io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
- struct iocb *iocb));
+ struct iocb *iocb, struct lio_event *lio));

#define get_ioctx(kioctx) do { \
BUG_ON(atomic_read(&(kioctx)->users) <= 0); \
Index: linux-2.6.20-rc6-mm3/include/linux/syscalls.h
===================================================================
--- linux-2.6.20-rc6-mm3.orig/include/linux/syscalls.h 2007-01-31 15:31:59.000000000 +0100
+++ linux-2.6.20-rc6-mm3/include/linux/syscalls.h 2007-01-31 15:58:55.000000000 +0100
@@ -317,6 +317,8 @@ asmlinkage long sys_io_getevents(aio_con
struct timespec __user *timeout);
asmlinkage long sys_io_submit(aio_context_t, long,
struct iocb __user * __user *);
+asmlinkage long sys_lio_submit(aio_context_t, int, long,
+ struct iocb __user * __user *, struct sigevent __user *);
asmlinkage long sys_io_cancel(aio_context_t ctx_id, struct iocb __user *iocb,
struct io_event __user *result);
asmlinkage ssize_t sys_sendfile(int out_fd, int in_fd,