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io_uring: grab ->fs as part of async offload 

[ Upstream commits 9392a27d88 and ff002b3018 ]

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>
5.4-rM2-2.2.x-imx-squashed
Jens Axboe 2020-02-28 15:20:18 -07:00 committed by Greg Kroah-Hartman
parent bfe3046eca
commit cac68d12c5
1 changed files with 46 additions and 0 deletions
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46
fs/io_uring.c
View File

@ -71,6 +71,7 @@
#include <linux/sizes.h>
#include <linux/hugetlb.h>
#include <linux/highmem.h>
#include <linux/fs_struct.h>
#include <uapi/linux/io_uring.h>
@ -334,6 +335,8 @@ struct io_kiocb {
u32 result;
u32 sequence;
struct fs_struct *fs;
struct work_struct work;
};
@ -651,6 +654,7 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
/* one is dropped after submission, the other at completion */
refcount_set(&req->refs, 2);
req->result = 0;
req->fs = NULL;
return req;
out:
percpu_ref_put(&ctx->refs);
@ -1663,6 +1667,16 @@ static int io_send_recvmsg(struct io_kiocb *req, const struct io_uring_sqe *sqe,
ret = -EINTR;
}
if (req->fs) {
struct fs_struct *fs = req->fs;
spin_lock(&req->fs->lock);
if (--fs->users)
fs = NULL;
spin_unlock(&req->fs->lock);
if (fs)
free_fs_struct(fs);
}
io_cqring_add_event(req->ctx, sqe->user_data, ret);
io_put_req(req);
return 0;
@ -2159,6 +2173,7 @@ static inline bool io_sqe_needs_user(const struct io_uring_sqe *sqe)
static void io_sq_wq_submit_work(struct work_struct *work)
{
struct io_kiocb *req = container_of(work, struct io_kiocb, work);
struct fs_struct *old_fs_struct = current->fs;
struct io_ring_ctx *ctx = req->ctx;
struct mm_struct *cur_mm = NULL;
struct async_list *async_list;
@ -2178,6 +2193,15 @@ restart:
/* Ensure we clear previously set non-block flag */
req->rw.ki_flags &= ~IOCB_NOWAIT;
if (req->fs != current->fs && current->fs != old_fs_struct) {
task_lock(current);
if (req->fs)
current->fs = req->fs;
else
current->fs = old_fs_struct;
task_unlock(current);
}
ret = 0;
if (io_sqe_needs_user(sqe) && !cur_mm) {
if (!mmget_not_zero(ctx->sqo_mm)) {
@ -2276,6 +2300,11 @@ out:
mmput(cur_mm);
}
revert_creds(old_cred);
if (old_fs_struct) {
task_lock(current);
current->fs = old_fs_struct;
task_unlock(current);
}
}
/*
@ -2503,6 +2532,23 @@ err:
req->user_data = s->sqe->user_data;
#if defined(CONFIG_NET)
switch (READ_ONCE(s->sqe->opcode)) {
case IORING_OP_SENDMSG:
case IORING_OP_RECVMSG:
spin_lock(&current->fs->lock);
if (!current->fs->in_exec) {
req->fs = current->fs;
req->fs->users++;
}
spin_unlock(&current->fs->lock);
if (!req->fs) {
ret = -EAGAIN;
goto err_req;
}
}
#endif
/*
* If we already have a head request, queue this one for async
* submittal once the head completes. If we don't have a head but