From 5da0fb1ab34ccfe6d49210b4f5a739c59fcbf25e Mon Sep 17 00:00:00 2001 From: yangerkun Date: Tue, 15 Oct 2019 21:59:29 +0800 Subject: io_uring: consider the overflow of sequence for timeout req Now we recalculate the sequence of timeout with 'req->sequence = ctx->cached_sq_head + count - 1', judge the right place to insert for timeout_list by compare the number of request we still expected for completion. But we have not consider about the situation of overflow: 1. ctx->cached_sq_head + count - 1 may overflow. And a bigger count for the new timeout req can have a small req->sequence. 2. cached_sq_head of now may overflow compare with before req. And it will lead the timeout req with small req->sequence. This overflow will lead to the misorder of timeout_list, which can lead to the wrong order of the completion of timeout_list. Fix it by reuse req->submit.sequence to store the count, and change the logic of inserting sort in io_timeout. Signed-off-by: yangerkun Signed-off-by: Jens Axboe --- fs/io_uring.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-) (limited to 'fs') diff --git a/fs/io_uring.c b/fs/io_uring.c index 38d274fc0f25..d2cb277da2f4 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1884,7 +1884,7 @@ static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer) static int io_timeout(struct io_kiocb *req, const struct io_uring_sqe *sqe) { - unsigned count, req_dist, tail_index; + unsigned count; struct io_ring_ctx *ctx = req->ctx; struct list_head *entry; struct timespec64 ts; @@ -1907,21 +1907,36 @@ static int io_timeout(struct io_kiocb *req, const struct io_uring_sqe *sqe) count = 1; req->sequence = ctx->cached_sq_head + count - 1; + /* reuse it to store the count */ + req->submit.sequence = count; req->flags |= REQ_F_TIMEOUT; /* * Insertion sort, ensuring the first entry in the list is always * the one we need first. */ - tail_index = ctx->cached_cq_tail - ctx->rings->sq_dropped; - req_dist = req->sequence - tail_index; spin_lock_irq(&ctx->completion_lock); list_for_each_prev(entry, &ctx->timeout_list) { struct io_kiocb *nxt = list_entry(entry, struct io_kiocb, list); - unsigned dist; + unsigned nxt_sq_head; + long long tmp, tmp_nxt; - dist = nxt->sequence - tail_index; - if (req_dist >= dist) + /* + * Since cached_sq_head + count - 1 can overflow, use type long + * long to store it. + */ + tmp = (long long)ctx->cached_sq_head + count - 1; + nxt_sq_head = nxt->sequence - nxt->submit.sequence + 1; + tmp_nxt = (long long)nxt_sq_head + nxt->submit.sequence - 1; + + /* + * cached_sq_head may overflow, and it will never overflow twice + * once there is some timeout req still be valid. + */ + if (ctx->cached_sq_head < nxt_sq_head) + tmp_nxt += UINT_MAX; + + if (tmp >= tmp_nxt) break; } list_add(&req->list, entry); -- cgit v1.2.3 From 491381ce07ca57f68c49c79a8a43da5b60749e32 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Thu, 17 Oct 2019 09:20:46 -0600 Subject: io_uring: fix up O_NONBLOCK handling for sockets We've got two issues with the non-regular file handling for non-blocking IO: 1) We don't want to re-do a short read in full for a non-regular file, as we can't just read the data again. 2) For non-regular files that don't support non-blocking IO attempts, we need to punt to async context even if the file is opened as non-blocking. Otherwise the caller always gets -EAGAIN. Add two new request flags to handle these cases. One is just a cache of the inode S_ISREG() status, the other tells io_uring that we always need to punt this request to async context, even if REQ_F_NOWAIT is set. Cc: stable@vger.kernel.org Reported-by: Hrvoje Zeba Tested-by: Hrvoje Zeba Signed-off-by: Jens Axboe --- fs/io_uring.c | 57 +++++++++++++++++++++++++++++++++++++++------------------ 1 file changed, 39 insertions(+), 18 deletions(-) (limited to 'fs') diff --git a/fs/io_uring.c b/fs/io_uring.c index d2cb277da2f4..b7d4085d6ffd 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -322,6 +322,8 @@ struct io_kiocb { #define REQ_F_FAIL_LINK 256 /* fail rest of links */ #define REQ_F_SHADOW_DRAIN 512 /* link-drain shadow req */ #define REQ_F_TIMEOUT 1024 /* timeout request */ +#define REQ_F_ISREG 2048 /* regular file */ +#define REQ_F_MUST_PUNT 4096 /* must be punted even for NONBLOCK */ u64 user_data; u32 result; u32 sequence; @@ -914,26 +916,26 @@ static int io_iopoll_check(struct io_ring_ctx *ctx, unsigned *nr_events, return ret; } -static void kiocb_end_write(struct kiocb *kiocb) +static void kiocb_end_write(struct io_kiocb *req) { - if (kiocb->ki_flags & IOCB_WRITE) { - struct inode *inode = file_inode(kiocb->ki_filp); + /* + * Tell lockdep we inherited freeze protection from submission + * thread. + */ + if (req->flags & REQ_F_ISREG) { + struct inode *inode = file_inode(req->file); - /* - * 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); + __sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE); } + file_end_write(req->file); } static void io_complete_rw(struct kiocb *kiocb, long res, long res2) { struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw); - kiocb_end_write(kiocb); + if (kiocb->ki_flags & IOCB_WRITE) + kiocb_end_write(req); if ((req->flags & REQ_F_LINK) && res != req->result) req->flags |= REQ_F_FAIL_LINK; @@ -945,7 +947,8 @@ static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2) { struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw); - kiocb_end_write(kiocb); + if (kiocb->ki_flags & IOCB_WRITE) + kiocb_end_write(req); if ((req->flags & REQ_F_LINK) && res != req->result) req->flags |= REQ_F_FAIL_LINK; @@ -1059,8 +1062,17 @@ static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s, if (!req->file) return -EBADF; - if (force_nonblock && !io_file_supports_async(req->file)) - force_nonblock = false; + if (S_ISREG(file_inode(req->file)->i_mode)) + req->flags |= REQ_F_ISREG; + + /* + * If the file doesn't support async, mark it as REQ_F_MUST_PUNT so + * we know to async punt it even if it was opened O_NONBLOCK + */ + if (force_nonblock && !io_file_supports_async(req->file)) { + req->flags |= REQ_F_MUST_PUNT; + return -EAGAIN; + } kiocb->ki_pos = READ_ONCE(sqe->off); kiocb->ki_flags = iocb_flags(kiocb->ki_filp); @@ -1081,7 +1093,8 @@ static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s, return ret; /* don't allow async punt if RWF_NOWAIT was requested */ - if (kiocb->ki_flags & IOCB_NOWAIT) + if ((kiocb->ki_flags & IOCB_NOWAIT) || + (req->file->f_flags & O_NONBLOCK)) req->flags |= REQ_F_NOWAIT; if (force_nonblock) @@ -1382,7 +1395,9 @@ static int io_read(struct io_kiocb *req, const struct sqe_submit *s, * need async punt anyway, so it's more efficient to do it * here. */ - if (force_nonblock && ret2 > 0 && ret2 < read_size) + if (force_nonblock && !(req->flags & REQ_F_NOWAIT) && + (req->flags & REQ_F_ISREG) && + ret2 > 0 && ret2 < read_size) ret2 = -EAGAIN; /* Catch -EAGAIN return for forced non-blocking submission */ if (!force_nonblock || ret2 != -EAGAIN) { @@ -1447,7 +1462,7 @@ static int io_write(struct io_kiocb *req, const struct sqe_submit *s, * released so that it doesn't complain about the held lock when * we return to userspace. */ - if (S_ISREG(file_inode(file)->i_mode)) { + if (req->flags & REQ_F_ISREG) { __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true); __sb_writers_release(file_inode(file)->i_sb, @@ -2282,7 +2297,13 @@ static int __io_queue_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req, int ret; ret = __io_submit_sqe(ctx, req, s, force_nonblock); - if (ret == -EAGAIN && !(req->flags & REQ_F_NOWAIT)) { + + /* + * We async punt it if the file wasn't marked NOWAIT, or if the file + * doesn't support non-blocking read/write attempts + */ + if (ret == -EAGAIN && (!(req->flags & REQ_F_NOWAIT) || + (req->flags & REQ_F_MUST_PUNT))) { struct io_uring_sqe *sqe_copy; sqe_copy = kmemdup(s->sqe, sizeof(*sqe_copy), GFP_KERNEL); -- cgit v1.2.3 From 8b07a65ad30e5612d9590fb50468ff4fa314cfc7 Mon Sep 17 00:00:00 2001 From: yangerkun Date: Thu, 17 Oct 2019 12:12:35 +0800 Subject: io_uring: fix logic error in io_timeout If ctx->cached_sq_head < nxt_sq_head, we should add UINT_MAX to tmp, not tmp_nxt. Fixes: 5da0fb1ab34c ("io_uring: consider the overflow of sequence for timeout req") Signed-off-by: yangerkun Signed-off-by: Jens Axboe --- fs/io_uring.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/io_uring.c b/fs/io_uring.c index b7d4085d6ffd..1d03afd74368 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1949,7 +1949,7 @@ static int io_timeout(struct io_kiocb *req, const struct io_uring_sqe *sqe) * once there is some timeout req still be valid. */ if (ctx->cached_sq_head < nxt_sq_head) - tmp_nxt += UINT_MAX; + tmp += UINT_MAX; if (tmp >= tmp_nxt) break; -- cgit v1.2.3