io_uring: grab ->fs as part of async offload
[ Upstream commits5.4-rM2-2.2.x-imx-squashed9392a27d88
andff002b3018
] Ensure that the async work grabs ->fs from the queueing task if the punted commands needs to do lookups. We don't have these two commits in 5.4-stable:ff002b3018
9392a27d88
because they don't apply with the rework that was done in how io_uring handles offload. Since there's no io-wq in 5.4, it doesn't make sense to do two patches. I'm attaching my port of the two for 5.4-stable, it's been tested. Please queue it up for the next 5.4-stable, thanks! Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org>
parent
bfe3046eca
commit
cac68d12c5
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@ -71,6 +71,7 @@
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#include <linux/sizes.h>
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#include <linux/hugetlb.h>
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#include <linux/highmem.h>
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#include <linux/fs_struct.h>
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#include <uapi/linux/io_uring.h>
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@ -334,6 +335,8 @@ struct io_kiocb {
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u32 result;
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u32 sequence;
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struct fs_struct *fs;
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struct work_struct work;
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};
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@ -651,6 +654,7 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
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/* one is dropped after submission, the other at completion */
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refcount_set(&req->refs, 2);
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req->result = 0;
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req->fs = NULL;
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return req;
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out:
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percpu_ref_put(&ctx->refs);
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@ -1663,6 +1667,16 @@ static int io_send_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
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ret = -EINTR;
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}
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if (req->fs) {
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struct fs_struct *fs = req->fs;
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spin_lock(&req->fs->lock);
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if (--fs->users)
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fs = NULL;
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spin_unlock(&req->fs->lock);
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if (fs)
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free_fs_struct(fs);
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}
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io_cqring_add_event(req->ctx, sqe->user_data, ret);
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io_put_req(req);
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return 0;
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@ -2159,6 +2173,7 @@ static inline bool io_sqe_needs_user(const struct io_uring_sqe *sqe)
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static void io_sq_wq_submit_work(struct work_struct *work)
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{
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struct io_kiocb *req = container_of(work, struct io_kiocb, work);
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struct fs_struct *old_fs_struct = current->fs;
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struct io_ring_ctx *ctx = req->ctx;
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struct mm_struct *cur_mm = NULL;
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struct async_list *async_list;
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@ -2178,6 +2193,15 @@ restart:
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/* Ensure we clear previously set non-block flag */
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req->rw.ki_flags &= ~IOCB_NOWAIT;
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if (req->fs != current->fs && current->fs != old_fs_struct) {
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task_lock(current);
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if (req->fs)
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current->fs = req->fs;
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else
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current->fs = old_fs_struct;
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task_unlock(current);
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}
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ret = 0;
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if (io_sqe_needs_user(sqe) && !cur_mm) {
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if (!mmget_not_zero(ctx->sqo_mm)) {
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@ -2276,6 +2300,11 @@ out:
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mmput(cur_mm);
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}
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revert_creds(old_cred);
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if (old_fs_struct) {
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task_lock(current);
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current->fs = old_fs_struct;
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task_unlock(current);
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}
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}
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/*
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@ -2503,6 +2532,23 @@ err:
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req->user_data = s->sqe->user_data;
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#if defined(CONFIG_NET)
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switch (READ_ONCE(s->sqe->opcode)) {
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case IORING_OP_SENDMSG:
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case IORING_OP_RECVMSG:
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spin_lock(¤t->fs->lock);
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if (!current->fs->in_exec) {
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req->fs = current->fs;
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req->fs->users++;
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}
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spin_unlock(¤t->fs->lock);
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if (!req->fs) {
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ret = -EAGAIN;
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goto err_req;
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}
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}
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#endif
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/*
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* If we already have a head request, queue this one for async
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* submittal once the head completes. If we don't have a head but
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