From 66ee59af630fd8d5f4f56fb28162857e629aa0ab Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 11 Feb 2015 19:56:46 +0100 Subject: fs: remove ki_nbytes There is no need to pass the total request length in the kiocb, as we already get passed in through the iov_iter argument. Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro --- fs/aio.c | 34 ++++++++++++++++++---------------- 1 file changed, 18 insertions(+), 16 deletions(-) (limited to 'fs/aio.c') diff --git a/fs/aio.c b/fs/aio.c index 118a2e0088d8..667054c7c067 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -1344,12 +1344,13 @@ typedef ssize_t (rw_iter_op)(struct kiocb *, struct iov_iter *); static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb, int rw, char __user *buf, unsigned long *nr_segs, + size_t *len, struct iovec **iovec, bool compat) { ssize_t ret; - *nr_segs = kiocb->ki_nbytes; + *nr_segs = *len; #ifdef CONFIG_COMPAT if (compat) @@ -1364,21 +1365,22 @@ static ssize_t aio_setup_vectored_rw(struct kiocb *kiocb, if (ret < 0) return ret; - /* ki_nbytes now reflect bytes instead of segs */ - kiocb->ki_nbytes = ret; + /* len now reflect bytes instead of segs */ + *len = ret; return 0; } static ssize_t aio_setup_single_vector(struct kiocb *kiocb, int rw, char __user *buf, unsigned long *nr_segs, + size_t len, struct iovec *iovec) { - if (unlikely(!access_ok(!rw, buf, kiocb->ki_nbytes))) + if (unlikely(!access_ok(!rw, buf, len))) return -EFAULT; iovec->iov_base = buf; - iovec->iov_len = kiocb->ki_nbytes; + iovec->iov_len = len; *nr_segs = 1; return 0; } @@ -1388,7 +1390,7 @@ static ssize_t aio_setup_single_vector(struct kiocb *kiocb, * Performs the initial checks and io submission. */ static ssize_t aio_run_iocb(struct kiocb *req, unsigned opcode, - char __user *buf, bool compat) + char __user *buf, size_t len, bool compat) { struct file *file = req->ki_filp; ssize_t ret; @@ -1423,21 +1425,21 @@ rw_common: if (!rw_op && !iter_op) return -EINVAL; - ret = (opcode == IOCB_CMD_PREADV || - opcode == IOCB_CMD_PWRITEV) - ? aio_setup_vectored_rw(req, rw, buf, &nr_segs, - &iovec, compat) - : aio_setup_single_vector(req, rw, buf, &nr_segs, - iovec); + if (opcode == IOCB_CMD_PREADV || opcode == IOCB_CMD_PWRITEV) + ret = aio_setup_vectored_rw(req, rw, buf, &nr_segs, + &len, &iovec, compat); + else + ret = aio_setup_single_vector(req, rw, buf, &nr_segs, + len, iovec); if (!ret) - ret = rw_verify_area(rw, file, &req->ki_pos, req->ki_nbytes); + ret = rw_verify_area(rw, file, &req->ki_pos, len); if (ret < 0) { if (iovec != inline_vecs) kfree(iovec); return ret; } - req->ki_nbytes = ret; + len = ret; /* XXX: move/kill - rw_verify_area()? */ /* This matches the pread()/pwrite() logic */ @@ -1450,7 +1452,7 @@ rw_common: file_start_write(file); if (iter_op) { - iov_iter_init(&iter, rw, iovec, nr_segs, req->ki_nbytes); + iov_iter_init(&iter, rw, iovec, nr_segs, len); ret = iter_op(req, &iter); } else { ret = rw_op(req, iovec, nr_segs, req->ki_pos); @@ -1553,10 +1555,10 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, req->ki_obj.user = user_iocb; req->ki_user_data = iocb->aio_data; req->ki_pos = iocb->aio_offset; - req->ki_nbytes = iocb->aio_nbytes; ret = aio_run_iocb(req, iocb->aio_lio_opcode, (char __user *)(unsigned long)iocb->aio_buf, + iocb->aio_nbytes, compat); if (ret) goto out_put_req; -- cgit v1.2.3 From 599bd19bdc4c6b20fd91d50f2f79dececbaf80c1 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 11 Feb 2015 19:59:44 +0100 Subject: fs: don't allow to complete sync iocbs through aio_complete The AIO interface is fairly complex because it tries to allow filesystems to always work async and then wakeup a synchronous caller through aio_complete. It turns out that basically no one was doing this to avoid the complexity and context switches, and we've already fixed up the remaining users and can now get rid of this case. Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro --- fs/aio.c | 24 +----------------------- 1 file changed, 1 insertion(+), 23 deletions(-) (limited to 'fs/aio.c') diff --git a/fs/aio.c b/fs/aio.c index 667054c7c067..8ca8df1c3550 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -778,22 +778,6 @@ static int kill_ioctx(struct mm_struct *mm, struct kioctx *ctx, return 0; } -/* wait_on_sync_kiocb: - * Waits on the given sync kiocb to complete. - */ -ssize_t wait_on_sync_kiocb(struct kiocb *req) -{ - while (!req->ki_ctx) { - set_current_state(TASK_UNINTERRUPTIBLE); - if (req->ki_ctx) - break; - io_schedule(); - } - __set_current_state(TASK_RUNNING); - return req->ki_user_data; -} -EXPORT_SYMBOL(wait_on_sync_kiocb); - /* * exit_aio: called when the last user of mm goes away. At this point, there is * no way for any new requests to be submited or any of the io_* syscalls to be @@ -1025,13 +1009,7 @@ void aio_complete(struct kiocb *iocb, long res, long res2) * ref, no other paths have a way to get another ref * - the sync task helpfully left a reference to itself in the iocb */ - if (is_sync_kiocb(iocb)) { - iocb->ki_user_data = res; - smp_wmb(); - iocb->ki_ctx = ERR_PTR(-EXDEV); - wake_up_process(iocb->ki_obj.tsk); - return; - } + BUG_ON(is_sync_kiocb(iocb)); if (iocb->ki_list.next) { unsigned long flags; -- cgit v1.2.3 From 04b2fa9f8f36ec6fb6fd1c9dc9df6fff0cd27323 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Mon, 2 Feb 2015 14:49:06 +0100 Subject: fs: split generic and aio kiocb Most callers in the kernel want to perform synchronous file I/O, but still have to bloat the stack with a full struct kiocb. Split out the parts needed in filesystem code from those in the aio code, and only allocate those needed to pass down argument on the stack. The aio code embedds the generic iocb in the one it allocates and can easily get back to it by using container_of. Also add a ->ki_complete method to struct kiocb, this is used to call into the aio code and thus removes the dependency on aio for filesystems impementing asynchronous operations. It will also allow other callers to substitute their own completion callback. We also add a new ->ki_flags field to work around the nasty layering violation recently introduced in commit 5e33f6 ("usb: gadget: ffs: add eventfd notification about ffs events"). Signed-off-by: Christoph Hellwig Signed-off-by: Al Viro --- fs/aio.c | 94 ++++++++++++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 65 insertions(+), 29 deletions(-) (limited to 'fs/aio.c') diff --git a/fs/aio.c b/fs/aio.c index 8ca8df1c3550..958286536a10 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -151,6 +151,38 @@ struct kioctx { unsigned id; }; +/* + * 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 + * successful cancellation - io_cancel() - does deliver the completion to + * userspace). + * + * And since most things don't implement kiocb cancellation and we'd really like + * kiocb completion to be lockless when possible, we use ki_cancel to + * synchronize cancellation and completion - we only set it to KIOCB_CANCELLED + * with xchg() or cmpxchg(), see batch_complete_aio() and kiocb_cancel(). + */ +#define KIOCB_CANCELLED ((void *) (~0ULL)) + +struct aio_kiocb { + struct kiocb common; + + struct kioctx *ki_ctx; + kiocb_cancel_fn *ki_cancel; + + struct iocb __user *ki_user_iocb; /* user's aiocb */ + __u64 ki_user_data; /* user's data for completion */ + + struct list_head ki_list; /* the aio core uses this + * for cancellation */ + + /* + * If the aio_resfd field of the userspace iocb is not zero, + * this is the underlying eventfd context to deliver events to. + */ + struct eventfd_ctx *ki_eventfd; +}; + /*------ sysctl variables----*/ static DEFINE_SPINLOCK(aio_nr_lock); unsigned long aio_nr; /* current system wide number of aio requests */ @@ -220,7 +252,7 @@ static int __init aio_setup(void) if (IS_ERR(aio_mnt)) panic("Failed to create aio fs mount."); - kiocb_cachep = KMEM_CACHE(kiocb, SLAB_HWCACHE_ALIGN|SLAB_PANIC); + 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)); @@ -480,8 +512,9 @@ static int aio_setup_ring(struct kioctx *ctx) #define AIO_EVENTS_FIRST_PAGE ((PAGE_SIZE - sizeof(struct aio_ring)) / sizeof(struct io_event)) #define AIO_EVENTS_OFFSET (AIO_EVENTS_PER_PAGE - AIO_EVENTS_FIRST_PAGE) -void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel) +void kiocb_set_cancel_fn(struct kiocb *iocb, kiocb_cancel_fn *cancel) { + struct aio_kiocb *req = container_of(iocb, struct aio_kiocb, common); struct kioctx *ctx = req->ki_ctx; unsigned long flags; @@ -496,7 +529,7 @@ void kiocb_set_cancel_fn(struct kiocb *req, kiocb_cancel_fn *cancel) } EXPORT_SYMBOL(kiocb_set_cancel_fn); -static int kiocb_cancel(struct kiocb *kiocb) +static int kiocb_cancel(struct aio_kiocb *kiocb) { kiocb_cancel_fn *old, *cancel; @@ -514,7 +547,7 @@ static int kiocb_cancel(struct kiocb *kiocb) cancel = cmpxchg(&kiocb->ki_cancel, old, KIOCB_CANCELLED); } while (cancel != old); - return cancel(kiocb); + return cancel(&kiocb->common); } static void free_ioctx(struct work_struct *work) @@ -550,13 +583,13 @@ static void free_ioctx_reqs(struct percpu_ref *ref) static void free_ioctx_users(struct percpu_ref *ref) { struct kioctx *ctx = container_of(ref, struct kioctx, users); - struct kiocb *req; + struct aio_kiocb *req; spin_lock_irq(&ctx->ctx_lock); while (!list_empty(&ctx->active_reqs)) { req = list_first_entry(&ctx->active_reqs, - struct kiocb, ki_list); + struct aio_kiocb, ki_list); list_del_init(&req->ki_list); kiocb_cancel(req); @@ -932,9 +965,9 @@ static void user_refill_reqs_available(struct kioctx *ctx) * Allocate a slot for an aio request. * Returns NULL if no requests are free. */ -static inline struct kiocb *aio_get_req(struct kioctx *ctx) +static inline struct aio_kiocb *aio_get_req(struct kioctx *ctx) { - struct kiocb *req; + struct aio_kiocb *req; if (!get_reqs_available(ctx)) { user_refill_reqs_available(ctx); @@ -955,10 +988,10 @@ out_put: return NULL; } -static void kiocb_free(struct kiocb *req) +static void kiocb_free(struct aio_kiocb *req) { - if (req->ki_filp) - fput(req->ki_filp); + 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); @@ -994,8 +1027,9 @@ out: /* aio_complete * Called when the io request on the given iocb is complete. */ -void aio_complete(struct kiocb *iocb, long res, long res2) +static void aio_complete(struct kiocb *kiocb, 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; @@ -1009,7 +1043,7 @@ void aio_complete(struct kiocb *iocb, long res, long res2) * 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(iocb)); + BUG_ON(is_sync_kiocb(kiocb)); if (iocb->ki_list.next) { unsigned long flags; @@ -1035,7 +1069,7 @@ void aio_complete(struct kiocb *iocb, long res, long res2) ev_page = kmap_atomic(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]); event = ev_page + pos % AIO_EVENTS_PER_PAGE; - event->obj = (u64)(unsigned long)iocb->ki_obj.user; + event->obj = (u64)(unsigned long)iocb->ki_user_iocb; event->data = iocb->ki_user_data; event->res = res; event->res2 = res2; @@ -1044,7 +1078,7 @@ void aio_complete(struct kiocb *iocb, long res, long res2) flush_dcache_page(ctx->ring_pages[pos / AIO_EVENTS_PER_PAGE]); pr_debug("%p[%u]: %p: %p %Lx %lx %lx\n", - ctx, tail, iocb, iocb->ki_obj.user, iocb->ki_user_data, + ctx, tail, iocb, iocb->ki_user_iocb, iocb->ki_user_data, res, res2); /* after flagging the request as done, we @@ -1091,7 +1125,6 @@ void aio_complete(struct kiocb *iocb, long res, long res2) percpu_ref_put(&ctx->reqs); } -EXPORT_SYMBOL(aio_complete); /* aio_read_events_ring * Pull an event off of the ioctx's event ring. Returns the number of @@ -1480,7 +1513,7 @@ rw_common: static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, struct iocb *iocb, bool compat) { - struct kiocb *req; + struct aio_kiocb *req; ssize_t ret; /* enforce forwards compatibility on users */ @@ -1503,11 +1536,14 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, if (unlikely(!req)) return -EAGAIN; - req->ki_filp = fget(iocb->aio_fildes); - if (unlikely(!req->ki_filp)) { + req->common.ki_filp = 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 = 0; if (iocb->aio_flags & IOCB_FLAG_RESFD) { /* @@ -1522,6 +1558,8 @@ 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 = put_user(KIOCB_KEY, &user_iocb->aio_key); @@ -1530,11 +1568,10 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb, goto out_put_req; } - req->ki_obj.user = user_iocb; + req->ki_user_iocb = user_iocb; req->ki_user_data = iocb->aio_data; - req->ki_pos = iocb->aio_offset; - ret = aio_run_iocb(req, iocb->aio_lio_opcode, + ret = aio_run_iocb(&req->common, iocb->aio_lio_opcode, (char __user *)(unsigned long)iocb->aio_buf, iocb->aio_nbytes, compat); @@ -1623,10 +1660,10 @@ SYSCALL_DEFINE3(io_submit, aio_context_t, ctx_id, long, nr, /* lookup_kiocb * Finds a given iocb for cancellation. */ -static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, - u32 key) +static struct aio_kiocb * +lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, u32 key) { - struct list_head *pos; + struct aio_kiocb *kiocb; assert_spin_locked(&ctx->ctx_lock); @@ -1634,9 +1671,8 @@ static struct kiocb *lookup_kiocb(struct kioctx *ctx, struct iocb __user *iocb, return NULL; /* TODO: use a hash or array, this sucks. */ - list_for_each(pos, &ctx->active_reqs) { - struct kiocb *kiocb = list_kiocb(pos); - if (kiocb->ki_obj.user == iocb) + list_for_each_entry(kiocb, &ctx->active_reqs, ki_list) { + if (kiocb->ki_user_iocb == iocb) return kiocb; } return NULL; @@ -1656,7 +1692,7 @@ SYSCALL_DEFINE3(io_cancel, aio_context_t, ctx_id, struct iocb __user *, iocb, struct io_event __user *, result) { struct kioctx *ctx; - struct kiocb *kiocb; + struct aio_kiocb *kiocb; u32 key; int ret; -- cgit v1.2.3