aio: refactor read/write iocb setup

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>

diff --git a/fs/aio.c b/fs/aio.c
index e5866e2..d07c27b 100644 (file)
--- 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;
 
@@ -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 @@ out_put:
        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 @@ out:
 /* 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;
        }
 }
@@ -1477,59 +1497,79 @@ 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) {
                /*
                 * 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 the held lock when we return to
-                * userspace.
+                * which will be released by another thread in
+                * aio_complete_rw().  Fool lockdep by telling it the lock got
+                * released so that it doesn't complain about the 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;
 }
 
@@ -1537,7 +1577,6 @@ 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 */
@@ -1560,16 +1599,6 @@ 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
@@ -1583,14 +1612,6 @@ 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);
@@ -1604,16 +1625,16 @@ 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);
@@ -1633,7 +1654,9 @@ 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;
 }