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authorIngo Molnar <mingo@kernel.org>2019-09-16 14:04:28 +0200
committerIngo Molnar <mingo@kernel.org>2019-09-16 14:05:04 +0200
commit563c4f85f9f0d63b712081d5b4522152cdcb8b6b (patch)
tree92351ab2d60d5fd7ce5745d21c9a60ce6d46c5dd /fs/io_uring.c
parent4adcdcea717cb2d8436bef00dd689aa5bc76f11b (diff)
parent09c7e8b21d67c3c78ab9701dbc0fb1e9f14a0ba5 (diff)
Merge branch 'sched/rt' into sched/core, to pick up -rt changes
Pick up the first couple of patches working towards PREEMPT_RT. Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'fs/io_uring.c')
-rw-r--r--fs/io_uring.c81
1 files changed, 64 insertions, 17 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index e2a66e12fbc6..012bc0efb9d3 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -202,7 +202,7 @@ struct async_list {
struct file *file;
off_t io_end;
- size_t io_pages;
+ size_t io_len;
};
struct io_ring_ctx {
@@ -333,7 +333,8 @@ struct io_kiocb {
#define REQ_F_IO_DRAIN 16 /* drain existing IO first */
#define REQ_F_IO_DRAINED 32 /* drain done */
#define REQ_F_LINK 64 /* linked sqes */
-#define REQ_F_FAIL_LINK 128 /* fail rest of links */
+#define REQ_F_LINK_DONE 128 /* linked sqes done */
+#define REQ_F_FAIL_LINK 256 /* fail rest of links */
u64 user_data;
u32 result;
u32 sequence;
@@ -429,7 +430,7 @@ static inline bool io_sequence_defer(struct io_ring_ctx *ctx,
if ((req->flags & (REQ_F_IO_DRAIN|REQ_F_IO_DRAINED)) != REQ_F_IO_DRAIN)
return false;
- return req->sequence > ctx->cached_cq_tail + ctx->sq_ring->dropped;
+ return req->sequence != ctx->cached_cq_tail + ctx->sq_ring->dropped;
}
static struct io_kiocb *io_get_deferred_req(struct io_ring_ctx *ctx)
@@ -632,6 +633,7 @@ static void io_req_link_next(struct io_kiocb *req)
nxt->flags |= REQ_F_LINK;
}
+ nxt->flags |= REQ_F_LINK_DONE;
INIT_WORK(&nxt->work, io_sq_wq_submit_work);
queue_work(req->ctx->sqo_wq, &nxt->work);
}
@@ -1064,8 +1066,44 @@ static int io_import_fixed(struct io_ring_ctx *ctx, int rw,
*/
offset = buf_addr - imu->ubuf;
iov_iter_bvec(iter, rw, imu->bvec, imu->nr_bvecs, offset + len);
- if (offset)
- iov_iter_advance(iter, offset);
+
+ if (offset) {
+ /*
+ * Don't use iov_iter_advance() here, as it's really slow for
+ * using the latter parts of a big fixed buffer - it iterates
+ * over each segment manually. We can cheat a bit here, because
+ * we know that:
+ *
+ * 1) it's a BVEC iter, we set it up
+ * 2) all bvecs are PAGE_SIZE in size, except potentially the
+ * first and last bvec
+ *
+ * So just find our index, and adjust the iterator afterwards.
+ * If the offset is within the first bvec (or the whole first
+ * bvec, just use iov_iter_advance(). This makes it easier
+ * since we can just skip the first segment, which may not
+ * be PAGE_SIZE aligned.
+ */
+ const struct bio_vec *bvec = imu->bvec;
+
+ if (offset <= bvec->bv_len) {
+ iov_iter_advance(iter, offset);
+ } else {
+ unsigned long seg_skip;
+
+ /* skip first vec */
+ offset -= bvec->bv_len;
+ seg_skip = 1 + (offset >> PAGE_SHIFT);
+
+ iter->bvec = bvec + seg_skip;
+ iter->nr_segs -= seg_skip;
+ iter->count -= (seg_skip << PAGE_SHIFT);
+ iter->iov_offset = offset & ~PAGE_MASK;
+ if (iter->iov_offset)
+ iter->count -= iter->iov_offset;
+ }
+ }
+
return 0;
}
@@ -1120,28 +1158,26 @@ static void io_async_list_note(int rw, struct io_kiocb *req, size_t len)
off_t io_end = kiocb->ki_pos + len;
if (filp == async_list->file && kiocb->ki_pos == async_list->io_end) {
- unsigned long max_pages;
+ unsigned long max_bytes;
/* Use 8x RA size as a decent limiter for both reads/writes */
- max_pages = filp->f_ra.ra_pages;
- if (!max_pages)
- max_pages = VM_READAHEAD_PAGES;
- max_pages *= 8;
-
- /* If max pages are exceeded, reset the state */
- len >>= PAGE_SHIFT;
- if (async_list->io_pages + len <= max_pages) {
+ max_bytes = filp->f_ra.ra_pages << (PAGE_SHIFT + 3);
+ if (!max_bytes)
+ max_bytes = VM_READAHEAD_PAGES << (PAGE_SHIFT + 3);
+
+ /* If max len are exceeded, reset the state */
+ if (async_list->io_len + len <= max_bytes) {
req->flags |= REQ_F_SEQ_PREV;
- async_list->io_pages += len;
+ async_list->io_len += len;
} else {
io_end = 0;
- async_list->io_pages = 0;
+ async_list->io_len = 0;
}
}
/* New file? Reset state. */
if (async_list->file != filp) {
- async_list->io_pages = 0;
+ async_list->io_len = 0;
async_list->file = filp;
}
async_list->io_end = io_end;
@@ -1630,6 +1666,8 @@ static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe)
INIT_LIST_HEAD(&poll->wait.entry);
init_waitqueue_func_entry(&poll->wait, io_poll_wake);
+ INIT_LIST_HEAD(&req->list);
+
mask = vfs_poll(poll->file, &ipt.pt) & poll->events;
spin_lock_irq(&ctx->completion_lock);
@@ -1844,6 +1882,10 @@ restart:
/* async context always use a copy of the sqe */
kfree(sqe);
+ /* req from defer and link list needn't decrease async cnt */
+ if (req->flags & (REQ_F_IO_DRAINED | REQ_F_LINK_DONE))
+ goto out;
+
if (!async_list)
break;
if (!list_empty(&req_list)) {
@@ -1891,6 +1933,7 @@ restart:
}
}
+out:
if (cur_mm) {
set_fs(old_fs);
unuse_mm(cur_mm);
@@ -1917,6 +1960,10 @@ static bool io_add_to_prev_work(struct async_list *list, struct io_kiocb *req)
ret = true;
spin_lock(&list->lock);
list_add_tail(&req->list, &list->list);
+ /*
+ * Ensure we see a simultaneous modification from io_sq_wq_submit_work()
+ */
+ smp_mb();
if (!atomic_read(&list->cnt)) {
list_del_init(&req->list);
ret = false;