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io_pgetevents & aio fsync V3

PATCH In review Christoph Hellwig 2 participants 10 messages Apr 15, 2018 – Apr 26, 2018

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#0 lore raw

Hi all,

this patch adds workqueue based fsync offload. Version of this patch have been floating around for a couple years, but we now have a user with seastar used by ScyllaDB (who sponsored this work) that really wants this in addition to the aio poll support. More details are in the patch itself.

Because the iocb types have been defined sine day one (and probably were supported by RHEL3) libaio already supports these calls as-is.

This also pulls in the aio cleanups and io_pgetevents support previously submitted and review as part of the aio poll series. The aio poll series will be resubmitted on top of this series

A git tree is available here:

git://git.infradead.org/users/hch/vfs.git aio-fsync.3

Gitweb:

http://git.infradead.org/users/hch/vfs.git/shortlog/refs/heads/aio-fsync.3

Changes since V2:
- don't introduce a use after free for lockdep sb release tracking
- set up list for cancellation before I/O submission

Changes since V1:
- remove a BUG_ON_ONE(is_sync_kiocb(kiocb));
- moved cancellation patches to the poll series
- improve a list_empty check

#1 lore raw

PATCH 1/7 aio: don't print the page size at boot time

The page size is in no way related to the aio code, and printing it in the (debug) dmesg at every boot serves no purpose.

---
 fs/aio.c | 3 ---
 1 file changed, 3 deletions(-)
fs/aio.c +0 -3
index 88d7927ffbc6..add46b06be86 100644
@@ -264,9 +264,6 @@ static int __init aio_setup(void)
 
 	kiocb_cachep = KMEM_CACHE(aio_kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC);
 	kioctx_cachep = KMEM_CACHE(kioctx,SLAB_HWCACHE_ALIGN|SLAB_PANIC);
-
-	pr_debug("sizeof(struct page) = %zu\n", sizeof(struct page));
-
 	return 0;
 }
 __initcall(aio_setup);
Signature · 1 line
2.17.0
#2 lore raw

PATCH 2/7 aio: remove an outdated BUG_ON and comment in aio_complete

In reply to Christoph Hellwig

These days we don't treat sync iocbs special in the aio completion code as they never use it. Remove the old comment and BUG_ON given that the current definition of is_sync_kiocb makes it impossible to hit.

---
 fs/aio.c | 9 ---------
 1 file changed, 9 deletions(-)
fs/aio.c +0 -9
index add46b06be86..7c1855afd723 100644
@@ -1107,15 +1107,6 @@ static void aio_complete(struct kiocb *kiocb, long res, long res2)
 		file_end_write(file);
 	}
 
-	/*
-	 * Special case handling for sync iocbs:
-	 *  - events go directly into the iocb for fast handling
-	 *  - the sync task with the iocb in its stack holds the single iocb
-	 *    ref, no other paths have a way to get another ref
-	 *  - the sync task helpfully left a reference to itself in the iocb
-	 */
-	BUG_ON(is_sync_kiocb(kiocb));
-
 	if (iocb->ki_list.next) {
 		unsigned long flags;
 
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Reviewed-by on v1 2/7
#3 lore raw

Re: [PATCH 2/7] aio: remove an outdated BUG_ON and comment in aio_complete

Quoted 5 lines · Christoph Hellwig

These days we don't treat sync iocbs special in the aio completion code as they never use it. Remove the old comment and BUG_ON given that the current definition of is_sync_kiocb makes it impossible to hit.

Looks ok,

--D

Quoted 27 lines
---
 fs/aio.c | 9 ---------
 1 file changed, 9 deletions(-)
fs/aio.c +0 -9
index add46b06be86..7c1855afd723 100644
@@ -1107,15 +1107,6 @@ static void aio_complete(struct kiocb *kiocb, long res, long res2)
 		file_end_write(file);
 	}
 
-	/*
-	 * Special case handling for sync iocbs:
-	 *  - events go directly into the iocb for fast handling
-	 *  - the sync task with the iocb in its stack holds the single iocb
-	 *    ref, no other paths have a way to get another ref
-	 *  - the sync task helpfully left a reference to itself in the iocb
-	 */
-	BUG_ON(is_sync_kiocb(kiocb));
-
 	if (iocb->ki_list.next) {
 		unsigned long flags;
 
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#4 lore raw

PATCH 3/7 aio: sanitize ki_list handling

In reply to Christoph Hellwig

Instead of handcoded non-null checks always initialize ki_list to an empty list and use list_empty / list_empty_careful on it. While we're at it also error out on a double call to kiocb_set_cancel_fn instead of ignoring it.

---
 fs/aio.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)
fs/aio.c +6 -7
index 7c1855afd723..18507743757a 100644
@@ -553,13 +553,12 @@ void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
 	struct kioctx *ctx = req->ki_ctx;
 	unsigned long flags;
 
-	spin_lock_irqsave(&ctx->ctx_lock, flags);
-
-	if (!req->ki_list.next)
-		list_add(&req->ki_list, &ctx->active_reqs);
+	if (WARN_ON_ONCE(!list_empty(&req->ki_list)))
+		return;
 
+	spin_lock_irqsave(&ctx->ctx_lock, flags);
+	list_add_tail(&req->ki_list, &ctx->active_reqs);
 	req->ki_cancel = cancel;
-
 	spin_unlock_irqrestore(&ctx->ctx_lock, flags);
 }
 EXPORT_SYMBOL(kiocb_set_cancel_fn);
@@ -1039,7 +1038,7 @@ static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
 		goto out_put;
 
 	percpu_ref_get(&ctx->reqs);
-
+	INIT_LIST_HEAD(&req->ki_list);
 	req->ki_ctx = ctx;
 	return req;
 out_put:
@@ -1107,7 +1106,7 @@ static void aio_complete(struct kiocb *kiocb, long res, long res2)
 		file_end_write(file);
 	}
 
-	if (iocb->ki_list.next) {
+	if (!list_empty_careful(&iocb->ki_list)) {
 		unsigned long flags;
 
 		spin_lock_irqsave(&ctx->ctx_lock, flags);
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#5 lore raw

PATCH 4/7 aio: remove the extra get_file/fput pair in io_submit_one

In reply to Christoph Hellwig

If we release the lockdep write protection token before calling into ->write_iter and thus never access the file pointer after an -EIOCBQUEUED return from ->write_iter or ->read_iter we don't need this extra reference.

---
 fs/aio.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)
fs/aio.c +5 -6
index 18507743757a..d7be32cdd1db 100644
@@ -1515,16 +1515,17 @@ static ssize_t aio_write(struct kiocb *req, struct iocb *iocb, bool vectored,
 		return ret;
 	ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
 	if (!ret) {
-		req->ki_flags |= IOCB_WRITE;
-		file_start_write(file);
-		ret = aio_ret(req, call_write_iter(file, req, &iter));
 		/*
 		 * We release freeze protection in aio_complete().  Fool lockdep
 		 * by telling it the lock got released so that it doesn't
 		 * complain about held lock when we return to userspace.
 		 */
-		if (S_ISREG(file_inode(file)->i_mode))
+		if (S_ISREG(file_inode(file)->i_mode)) {
+			__sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true);
 			__sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
+		}
+		req->ki_flags |= IOCB_WRITE;
+		ret = aio_ret(req, call_write_iter(file, req, &iter));
 	}
 	kfree(iovec);
 	return ret;
@@ -1599,7 +1600,6 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 	req->ki_user_iocb = user_iocb;
 	req->ki_user_data = iocb->aio_data;
 
-	get_file(file);
 	switch (iocb->aio_lio_opcode) {
 	case IOCB_CMD_PREAD:
 		ret = aio_read(&req->common, iocb, false, compat);
@@ -1618,7 +1618,6 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 		ret = -EINVAL;
 		break;
 	}
-	fput(file);
 
 	if (ret && ret != -EIOCBQUEUED)
 		goto out_put_req;
Signature · 1 line
2.17.0
#6 lore raw

Re: [PATCH 4/7] aio: remove the extra get_file/fput pair in io_submit_one

Quoted 4 lines · Christoph Hellwig

If we release the lockdep write protection token before calling into ->write_iter and thus never access the file pointer after an -EIOCBQUEUED return from ->write_iter or ->read_iter we don't need this extra reference.

Hmm, subtleties lurk to this unfamiliar reader...

Quoted 14 lines
---
 fs/aio.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)
fs/aio.c +0 -1
index 18507743757a..d7be32cdd1db 100644
@@ -1515,16 +1515,17 @@ static ssize_t aio_write(struct kiocb *req, struct iocb *iocb, bool vectored,
 		return ret;
 	ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
 	if (!ret) {
-		req->ki_flags |= IOCB_WRITE;

fs/aio.c static ssize_t aio_write(struct kiocb *req, struct iocb *iocb, bool vectored, · line 1524

Quoted 10 lines
fs/aio.c +2 -3
-		file_start_write(file);
-		ret = aio_ret(req, call_write_iter(file, req, &iter));
 		/*
 		 * We release freeze protection in aio_complete().  Fool lockdep
 		 * by telling it the lock got released so that it doesn't
 		 * complain about held lock when we return to userspace.
 		 */
-		if (S_ISREG(file_inode(file)->i_mode))
+		if (S_ISREG(file_inode(file)->i_mode)) {
+			__sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true);

It took me a while to figure out that this ^^^ is the same as the file_start_write call that you remove above, can you please update the comment to note that we take freeze protection for the file before screwing with lockdep? e.g.,

/*
* Open-code file_start_write here to grab freeze protection, which will
* be released by another thread in aio_complete(). Fool lockdep by
* telling it the lock got released so that it doesn't complain about
* held lock when we return to userspace.
*/

fs/aio.c static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, · line 1602

Quoted 12 lines
fs/aio.c +3 -1
 			__sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
+		}
+		req->ki_flags |= IOCB_WRITE;
+		ret = aio_ret(req, call_write_iter(file, req, &iter));
 	}
 	kfree(iovec);
 	return ret;
@@ -1599,7 +1600,6 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 	req->ki_user_iocb = user_iocb;
 	req->ki_user_data = iocb->aio_data;
 
-	get_file(file);

Here we have a reference to *file, but...

fs/aio.c static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, · line 1621

Quoted 8 lines
fs/aio.c +0 -1
 	switch (iocb->aio_lio_opcode) {
 	case IOCB_CMD_PREAD:
 		ret = aio_read(&req->common, iocb, false, compat);
@@ -1618,7 +1618,6 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 		ret = -EINVAL;
 		break;
 	}
-	fput(file);

...by the time we get to here the reference may have gone away, but you'd have to dig through aio_{read,write} -> call_{r,w}_iter -> {r,w}_iter in order to figure out that the reference isn't valid anymore on a EIOCBQUEUED return.

That's a little subtle, can you add a comment about that?

/*
* If ret is EIOCBQUEUED here, the ->read_iter/->write_iter dropped the
* reference on *file. We don't ourselves ensure a reference to the
* file, so we must be careful about that here and in the subfunctions. */

--D

Quoted 6 lines
fs/aio.c +0 -0
 	if (ret && ret != -EIOCBQUEUED)
 		goto out_put_req;
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#7 lore raw

PATCH 5/7 aio: refactor read/write iocb setup

In reply to Christoph Hellwig

Don't reference the kiocb structure from the common aio code, and move any use of it into helper specific to the read/write path. This is in preparation for aio_poll support that wants to use the space for different fields.

---
 fs/aio.c | 159 +++++++++++++++++++++++++++++++------------------------
 1 file changed, 91 insertions(+), 68 deletions(-)
fs/aio.c +91 -68
index d7be32cdd1db..d4dd002712c8 100644
@@ -170,7 +170,9 @@ struct kioctx {
 #define KIOCB_CANCELLED		((void *) (~0ULL))
 
 struct aio_kiocb {
-	struct kiocb		common;
+	union {
+		struct kiocb		rw;
+	};
 
 	struct kioctx		*ki_ctx;
 	kiocb_cancel_fn		*ki_cancel;
@@ -549,7 +551,7 @@ static int aio_setup_ring(struct kioctx *ctx, unsigned int nr_events)
 
 void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel)
 {
-	struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, common);
+	struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, rw);
 	struct kioctx *ctx = req->ki_ctx;
 	unsigned long flags;
 
@@ -581,7 +583,7 @@ static int kiocb_cancel(struct aio_kiocb *kiocb)
 		cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED);
 	} while (cancel != old);
 
-	return cancel(&kiocb->common);
+	return cancel(&kiocb->rw);
 }
 
 /*
@@ -1046,15 +1048,6 @@ static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx)
 	return NULL;
 }
 
-static void kiocb_free(struct aio_kiocb *req)
-{
-	if (req->common.ki_filp)
-		fput(req->common.ki_filp);
-	if (req->ki_eventfd != NULL)
-		eventfd_ctx_put(req->ki_eventfd);
-	kmem_cache_free(kiocb_cachep, req);
-}
-
 static struct kioctx *lookup_ioctx(unsigned long ctx_id)
 {
 	struct aio_ring __user *ring  = (void __user *)ctx_id;
@@ -1085,27 +1078,14 @@ static struct kioctx *lookup_ioctx(unsigned long ctx_id)
 /* aio_complete
  *	Called when the io request on the given iocb is complete.
  */
-static void aio_complete(struct kiocb *kiocb, long res, long res2)
+static void aio_complete(struct aio_kiocb *iocb, long res, long res2)
 {
-	struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, common);
 	struct kioctx	*ctx = iocb->ki_ctx;
 	struct aio_ring	*ring;
 	struct io_event	*ev_page, *event;
 	unsigned tail, pos, head;
 	unsigned long	flags;
 
-	if (kiocb->ki_flags & IOCB_WRITE) {
-		struct file *file = kiocb->ki_filp;
-
-		/*
-		 * Tell lockdep we inherited freeze protection from submission
-		 * thread.
-		 */
-		if (S_ISREG(file_inode(file)->i_mode))
-			__sb_writers_acquired(file_inode(file)->i_sb, SB_FREEZE_WRITE);
-		file_end_write(file);
-	}
-
 	if (!list_empty_careful(&iocb->ki_list)) {
 		unsigned long flags;
 
@@ -1167,11 +1147,12 @@ static void aio_complete(struct kiocb *kiocb, long res, long res2)
 	 * eventfd. The eventfd_signal() function is safe to be called
 	 * from IRQ context.
 	 */
-	if (iocb->ki_eventfd != NULL)
+	if (iocb->ki_eventfd) {
 		eventfd_signal(iocb->ki_eventfd, 1);
+		eventfd_ctx_put(iocb->ki_eventfd);
+	}
 
-	/* everything turned out well, dispose of the aiocb. */
-	kiocb_free(iocb);
+	kmem_cache_free(kiocb_cachep, iocb);
 
 	/*
 	 * We have to order our ring_info tail store above and test
@@ -1434,6 +1415,45 @@ SYSCALL_DEFINE1(io_destroy, aio_context_t, ctx)
 	return -EINVAL;
 }
 
+static void aio_complete_rw(struct kiocb *kiocb, long res, long res2)
+{
+	struct aio_kiocb *iocb = container_of(kiocb, struct aio_kiocb, rw);
+
+	if (kiocb->ki_flags & IOCB_WRITE) {
+		struct inode *inode = file_inode(kiocb->ki_filp);
+
+		/*
+		 * Tell lockdep we inherited freeze protection from submission
+		 * thread.
+		 */
+		if (S_ISREG(inode->i_mode))
+			__sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
+		file_end_write(kiocb->ki_filp);
+	}
+
+	fput(kiocb->ki_filp);
+	aio_complete(iocb, res, res2);
+}
+
+static int aio_prep_rw(struct kiocb *req, struct iocb *iocb)
+{
+	int ret;
+
+	req->ki_filp = fget(iocb->aio_fildes);
+	if (unlikely(!req->ki_filp))
+		return -EBADF;
+	req->ki_complete = aio_complete_rw;
+	req->ki_pos = iocb->aio_offset;
+	req->ki_flags = iocb_flags(req->ki_filp);
+	if (iocb->aio_flags & IOCB_FLAG_RESFD)
+		req->ki_flags |= IOCB_EVENTFD;
+	req->ki_hint = file_write_hint(req->ki_filp);
+	ret = kiocb_set_rw_flags(req, iocb->aio_rw_flags);
+	if (unlikely(ret))
+		fput(req->ki_filp);
+	return ret;
+}
+
 static int aio_setup_rw(int rw, struct iocb *iocb, struct iovec **iovec,
 		bool vectored, bool compat, struct iov_iter *iter)
 {
@@ -1453,7 +1473,7 @@ static int aio_setup_rw(int rw, struct iocb *iocb, struct iovec **iovec,
 	return import_iovec(rw, buf, len, UIO_FASTIOV, iovec, iter);
 }
 
-static inline ssize_t aio_ret(struct kiocb *req, ssize_t ret)
+static inline ssize_t aio_rw_ret(struct kiocb *req, ssize_t ret)
 {
 	switch (ret) {
 	case -EIOCBQUEUED:
@@ -1469,7 +1489,7 @@ static inline ssize_t aio_ret(struct kiocb *req, ssize_t ret)
 		ret = -EINTR;
 		/*FALLTHRU*/
 	default:
-		aio_complete(req, ret, 0);
+		aio_complete_rw(req, ret, 0);
 		return 0;
 	}
 }
@@ -1477,57 +1497,77 @@ static inline ssize_t aio_ret(struct kiocb *req, ssize_t ret)
 static ssize_t aio_read(struct kiocb *req, struct iocb *iocb, bool vectored,
 		bool compat)
 {
-	struct file *file = req->ki_filp;
 	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
 	struct iov_iter iter;
+	struct file *file;
 	ssize_t ret;
 
+	ret = aio_prep_rw(req, iocb);
+	if (ret)
+		return ret;
+	file = req->ki_filp;
+
+	ret = -EBADF;
 	if (unlikely(!(file->f_mode & FMODE_READ)))
-		return -EBADF;
+		goto out_fput;
+	ret = -EINVAL;
 	if (unlikely(!file->f_op->read_iter))
-		return -EINVAL;
+		goto out_fput;
 
 	ret = aio_setup_rw(READ, iocb, &iovec, vectored, compat, &iter);
 	if (ret)
-		return ret;
+		goto out_fput;
 	ret = rw_verify_area(READ, file, &req->ki_pos, iov_iter_count(&iter));
 	if (!ret)
-		ret = aio_ret(req, call_read_iter(file, req, &iter));
+		ret = aio_rw_ret(req, call_read_iter(file, req, &iter));
 	kfree(iovec);
+out_fput:
+	if (unlikely(ret && ret != -EIOCBQUEUED))
+		fput(file);
 	return ret;
 }
 
 static ssize_t aio_write(struct kiocb *req, struct iocb *iocb, bool vectored,
 		bool compat)
 {
-	struct file *file = req->ki_filp;
 	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
 	struct iov_iter iter;
+	struct file *file;
 	ssize_t ret;
 
+	ret = aio_prep_rw(req, iocb);
+	if (ret)
+		return ret;
+	file = req->ki_filp;
+
+	ret = -EBADF;
 	if (unlikely(!(file->f_mode & FMODE_WRITE)))
-		return -EBADF;
+		goto out_fput;
+	ret = -EINVAL;
 	if (unlikely(!file->f_op->write_iter))
-		return -EINVAL;
+		goto out_fput;
 
 	ret = aio_setup_rw(WRITE, iocb, &iovec, vectored, compat, &iter);
 	if (ret)
-		return ret;
+		goto out_fput;
 	ret = rw_verify_area(WRITE, file, &req->ki_pos, iov_iter_count(&iter));
 	if (!ret) {
 		/*
-		 * We release freeze protection in aio_complete().  Fool lockdep
-		 * by telling it the lock got released so that it doesn't
-		 * complain about held lock when we return to userspace.
+		 * We release freeze protection in aio_complete_rw().  Fool
+		 * lockdep by telling it the lock got released so that it
+		 * doesn't complain about held lock when we return to userspace.
 		 */
 		if (S_ISREG(file_inode(file)->i_mode)) {
 			__sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true);
 			__sb_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
 		}
 		req->ki_flags |= IOCB_WRITE;
-		ret = aio_ret(req, call_write_iter(file, req, &iter));
+		ret = aio_rw_ret(req, call_write_iter(file, req, &iter));
 	}
 	kfree(iovec);
+out_fput:
+	if (unlikely(ret && ret != -EIOCBQUEUED))
+		fput(file);
 	return ret;
 }
 
@@ -1535,7 +1575,6 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 			 struct iocb *iocb, bool compat)
 {
 	struct aio_kiocb *req;
-	struct file *file;
 	ssize_t ret;
 
 	/* enforce forwards compatibility on users */
@@ -1558,16 +1597,6 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 	if (unlikely(!req))
 		return -EAGAIN;
 
-	req->common.ki_filp = file = fget(iocb->aio_fildes);
-	if (unlikely(!req->common.ki_filp)) {
-		ret = -EBADF;
-		goto out_put_req;
-	}
-	req->common.ki_pos = iocb->aio_offset;
-	req->common.ki_complete = aio_complete;
-	req->common.ki_flags = iocb_flags(req->common.ki_filp);
-	req->common.ki_hint = file_write_hint(file);
-
 	if (iocb->aio_flags & IOCB_FLAG_RESFD) {
 		/*
 		 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
@@ -1581,14 +1610,6 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 			req->ki_eventfd = NULL;
 			goto out_put_req;
 		}
-
-		req->common.ki_flags |= IOCB_EVENTFD;
-	}
-
-	ret = kiocb_set_rw_flags(&req->common, iocb->aio_rw_flags);
-	if (unlikely(ret)) {
-		pr_debug("EINVAL: aio_rw_flags\n");
-		goto out_put_req;
 	}
 
 	ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
@@ -1602,16 +1623,16 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 
 	switch (iocb->aio_lio_opcode) {
 	case IOCB_CMD_PREAD:
-		ret = aio_read(&req->common, iocb, false, compat);
+		ret = aio_read(&req->rw, iocb, false, compat);
 		break;
 	case IOCB_CMD_PWRITE:
-		ret = aio_write(&req->common, iocb, false, compat);
+		ret = aio_write(&req->rw, iocb, false, compat);
 		break;
 	case IOCB_CMD_PREADV:
-		ret = aio_read(&req->common, iocb, true, compat);
+		ret = aio_read(&req->rw, iocb, true, compat);
 		break;
 	case IOCB_CMD_PWRITEV:
-		ret = aio_write(&req->common, iocb, true, compat);
+		ret = aio_write(&req->rw, iocb, true, compat);
 		break;
 	default:
 		pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
@@ -1625,7 +1646,9 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 out_put_req:
 	put_reqs_available(ctx, 1);
 	percpu_ref_put(&ctx->reqs);
-	kiocb_free(req);
+	if (req->ki_eventfd)
+		eventfd_ctx_put(req->ki_eventfd);
+	kmem_cache_free(kiocb_cachep, req);
 	return ret;
 }
 
Signature · 7 lines
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#8 lore raw

PATCH 6/7 aio: implement IOCB_CMD_FSYNC and IOCB_CMD_FDSYNC

In reply to Christoph Hellwig

Simple workqueue offload for now, but prepared for adding a real aio_fsync method if the need arises. Based on an earlier patch from Dave Chinner.

---
 fs/aio.c | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)
fs/aio.c +43 -0
index d4dd002712c8..de56496ba86c 100644
@@ -156,6 +156,12 @@ struct kioctx {
 	unsigned		id;
 };
 
+struct fsync_iocb {
+	struct work_struct	work;
+	struct file		*file;
+	bool			datasync;
+};
+
 /*
  * We use ki_cancel == KIOCB_CANCELLED to indicate that a kiocb has been either
  * cancelled or completed (this makes a certain amount of sense because
@@ -172,6 +178,7 @@ struct kioctx {
 struct aio_kiocb {
 	union {
 		struct kiocb		rw;
+		struct fsync_iocb	fsync;
 	};
 
 	struct kioctx		*ki_ctx;
@@ -1571,6 +1578,36 @@ static ssize_t aio_write(struct kiocb *req, struct iocb *iocb, bool vectored,
 	return ret;
 }
 
+static void aio_fsync_work(struct work_struct *work)
+{
+	struct fsync_iocb *req = container_of(work, struct fsync_iocb, work);
+	int ret;
+
+	ret = vfs_fsync(req->file, req->datasync);
+	fput(req->file);
+	aio_complete(container_of(req, struct aio_kiocb, fsync), ret, 0);
+}
+
+static int aio_fsync(struct fsync_iocb *req, struct iocb *iocb, bool datasync)
+{
+	if (unlikely(iocb->aio_buf || iocb->aio_offset || iocb->aio_nbytes ||
+			iocb->aio_rw_flags))
+		return -EINVAL;
+
+	req->file = fget(iocb->aio_fildes);
+	if (unlikely(!req->file))
+		return -EBADF;
+	if (unlikely(!req->file->f_op->fsync)) {
+		fput(req->file);
+		return -EINVAL;
+	}
+
+	req->datasync = datasync;
+	INIT_WORK(&req->work, aio_fsync_work);
+	schedule_work(&req->work);
+	return -EIOCBQUEUED;
+}
+
 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 			 struct iocb *iocb, bool compat)
 {
@@ -1634,6 +1671,12 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 	case IOCB_CMD_PWRITEV:
 		ret = aio_write(&req->rw, iocb, true, compat);
 		break;
+	case IOCB_CMD_FSYNC:
+		ret = aio_fsync(&req->fsync, iocb, false);
+		break;
+	case IOCB_CMD_FDSYNC:
+		ret = aio_fsync(&req->fsync, iocb, true);
+		break;
 	default:
 		pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
 		ret = -EINVAL;
Signature · 7 lines
2.17.0

--
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the body to [email protected].  For more info on Linux AIO,
see: http://www.kvack.org/aio/
Don't email: <a href=mailto:"[email protected]">[email protected]</a>
#9 lore raw

PATCH 7/7 aio: implement io_pgetevents

In reply to Christoph Hellwig

This is the io_getevents equivalent of ppoll/pselect and allows to properly mix signals and aio completions (especially with IOCB_CMD_POLL) and atomically executes the following sequence:

	sigset_t origmask;

	pthread_sigmask(SIG_SETMASK, &sigmask, &origmask);
	ret = io_getevents(ctx, min_nr, nr, events, timeout);
	pthread_sigmask(SIG_SETMASK, &origmask, NULL);

Note that unlike many other signal related calls we do not pass a sigmask size, as that would get us to 7 arguments, which aren't easily supported by the syscall infrastructure. It seems a lot less painful to just add a new syscall variant in the unlikely case we're going to increase the sigset size.

---
 arch/x86/entry/syscalls/syscall_32.tbl |   1 +
 arch/x86/entry/syscalls/syscall_64.tbl |   1 +
 fs/aio.c                               | 114 ++++++++++++++++++++++---
 include/linux/compat.h                 |   7 ++
 include/linux/syscalls.h               |   6 ++
 include/uapi/asm-generic/unistd.h      |   4 +-
 include/uapi/linux/aio_abi.h           |   6 ++
 kernel/sys_ni.c                        |   2 +
 8 files changed, 130 insertions(+), 11 deletions(-)
arch/x86/entry/syscalls/syscall_32.tbl +1 -0
index c58f75b088c5..99b6f7a36178 100644
@@ -391,3 +391,4 @@
 382	i386	pkey_free		sys_pkey_free
 383	i386	statx			sys_statx
 384	i386	arch_prctl		sys_arch_prctl			compat_sys_arch_prctl
+385	i386	io_pgetevents		sys_io_pgetevents		compat_sys_io_pgetevents
arch/x86/entry/syscalls/syscall_64.tbl +1 -0
index 5aef183e2f85..e995cd2b4e65 100644
@@ -339,6 +339,7 @@
 330	common	pkey_alloc		sys_pkey_alloc
 331	common	pkey_free		sys_pkey_free
 332	common	statx			sys_statx
+333	common	io_pgetevents		sys_io_pgetevents
 
 #
 # x32-specific system call numbers start at 512 to avoid cache impact
fs/aio.c +104 -10

140 lines not on this page · raw message

include/linux/compat.h +7 -0
index f188eab10570..fdd068f192c1 100644
@@ -310,6 +310,7 @@ extern int put_compat_rusage(const struct rusage *,
 			     struct compat_rusage __user *);
 
 struct compat_siginfo;
+struct __compat_aio_sigset;
 
 struct compat_dirent {
 	u32		d_ino;
@@ -528,6 +529,12 @@ asmlinkage long compat_sys_io_getevents(compat_aio_context_t ctx_id,
 					compat_long_t nr,
 					struct io_event __user *events,
 					struct compat_timespec __user *timeout);
+asmlinkage long compat_sys_io_pgetevents(compat_aio_context_t ctx_id,
+					compat_long_t min_nr,
+					compat_long_t nr,
+					struct io_event __user *events,
+					struct compat_timespec __user *timeout,
+					const struct __compat_aio_sigset __user *usig);
 
 /* fs/cookies.c */
 asmlinkage long compat_sys_lookup_dcookie(u32, u32, char __user *, compat_size_t);
include/linux/syscalls.h +6 -0
index b961184f597a..c40cf5ec24c9 100644
@@ -264,6 +264,12 @@ asmlinkage long sys_io_getevents(aio_context_t ctx_id,
 				long nr,
 				struct io_event __user *events,
 				struct timespec __user *timeout);
+asmlinkage long sys_io_pgetevents(aio_context_t ctx_id,
+				long min_nr,
+				long nr,
+				struct io_event __user *events,
+				struct timespec __user *timeout,
+				const struct __aio_sigset *sig);
 
 /* fs/xattr.c */
 asmlinkage long sys_setxattr(const char __user *path, const char __user *name,
include/uapi/asm-generic/unistd.h +3 -1
index 8bcb186c6f67..42990676a55e 100644
@@ -732,9 +732,11 @@ __SYSCALL(__NR_pkey_alloc,    sys_pkey_alloc)
 __SYSCALL(__NR_pkey_free,     sys_pkey_free)
 #define __NR_statx 291
 __SYSCALL(__NR_statx,     sys_statx)
+#define __NR_io_pgetevents 292
+__SC_COMP(__NR_io_pgetevents, sys_io_pgetevents, compat_sys_io_pgetevents)
 
 #undef __NR_syscalls
-#define __NR_syscalls 292
+#define __NR_syscalls 293
 
 /*
  * 32 bit systems traditionally used different
include/uapi/linux/aio_abi.h +6 -0
index a04adbc70ddf..2c0a3415beee 100644
@@ -29,6 +29,7 @@
 
 #include <linux/types.h>
 #include <linux/fs.h>
+#include <linux/signal.h>
 #include <asm/byteorder.h>
 
 typedef __kernel_ulong_t aio_context_t;
@@ -108,5 +109,10 @@ struct iocb {
 #undef IFBIG
 #undef IFLITTLE
 
+struct __aio_sigset {
+	sigset_t __user	*sigmask;
+	size_t		sigsetsize;
+};
+
 #endif /* __LINUX__AIO_ABI_H */
 
kernel/sys_ni.c +2 -0
index 6cafc008f6db..7571cf9d7424 100644
@@ -33,7 +33,9 @@ COND_SYSCALL(io_submit);
 COND_SYSCALL_COMPAT(io_submit);
 COND_SYSCALL(io_cancel);
 COND_SYSCALL(io_getevents);
+COND_SYSCALL(io_pgetevents);
 COND_SYSCALL_COMPAT(io_getevents);
+COND_SYSCALL_COMPAT(io_pgetevents);
 
 /* fs/xattr.c */
 
Signature · 1 line
2.17.0