[PATCH 3/6] aio: refactor read/write iocb setup

Christoph Hellwig
2018-03-28T07:26:59Z

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.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
---
fs/aio.c | 167 ++++++++++++++++++++++++++++++++++++---------------------------
1 file changed, 95 insertions(+), 72 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index f536b0f249d4..50c4a0554cc6 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -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;

@@ -582,7 +584,7 @@ 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);
}

static void free_ioctx(struct work_struct *work)
@@ -1040,15 +1042,6 @@ 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;
@@ -1079,27 +1072,14 @@ 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 (iocb->ki_list.next) {
unsigned long flags;

@@ -1161,11 +1141,12 @@ 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
@@ -1428,6 +1409,45 @@ 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)
{
@@ -1447,7 +1467,7 @@ 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:
@@ -1463,7 +1483,7 @@ 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;
}
}
@@ -1471,56 +1491,78 @@ 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) {
+ struct inode *inode = file_inode(file);
+
req->ki_flags |= IOCB_WRITE;
file_start_write(file);
- ret = aio_ret(req, call_write_iter(file, req, &iter));
+ ret = aio_rw_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.
+ * 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_writers_release(file_inode(file)->i_sb, SB_FREEZE_WRITE);
+ if (S_ISREG(inode->i_mode))
+ __sb_writers_release(inode->i_sb, SB_FREEZE_WRITE);
}
kfree(iovec);
+out_fput:
+ if (unlikely(ret && ret != -EIOCBQUEUED))
+ fput(file);
return ret;
}

@@ -1528,7 +1570,6 @@ 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 */
@@ -1551,16 +1592,6 @@ 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
@@ -1574,14 +1605,6 @@ 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);
@@ -1593,26 +1616,24 @@ 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);
+ 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);
ret = -EINVAL;
break;
}
- fput(file);

if (ret && ret != -EIOCBQUEUED)
goto out_put_req;
@@ -1620,7 +1641,9 @@ 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;
}

--
2.14.2