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Message-ID: <160596813488.154728.6654456287509529880.stgit@warthog.procyon.org.uk>
Date: Sat, 21 Nov 2020 14:15:34 +0000
From: David Howells <dhowells@...hat.com>
To: Pavel Begunkov <asml.silence@...il.com>,
Matthew Wilcox <willy@...radead.org>,
Jens Axboe <axboe@...nel.dk>,
Alexander Viro <viro@...iv.linux.org.uk>
Cc: dhowells@...hat.com,
Linus Torvalds <torvalds@...ux-foundation.org>,
linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 17/29] iov_iter: Split iov_iter_revert()
Split iov_iter_revert() by type.
Signed-off-by: David Howells <dhowells@...hat.com>
---
lib/iov_iter.c | 132 ++++++++++++++++++++++++++++++++++----------------------
1 file changed, 79 insertions(+), 53 deletions(-)
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 9859b4b8a116..b8e3da20547e 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1319,71 +1319,97 @@ static void discard_advance(struct iov_iter *i, size_t size)
i->count -= size;
}
-static void xxx_revert(struct iov_iter *i, size_t unroll)
+static void iovec_kvec_revert(struct iov_iter *i, size_t unroll)
{
+ const struct iovec *iov = i->iov;
if (!unroll)
return;
if (WARN_ON(unroll > MAX_RW_COUNT))
return;
i->count += unroll;
- if (unlikely(iov_iter_is_pipe(i))) {
- struct pipe_inode_info *pipe = i->pipe;
- unsigned int p_mask = pipe->ring_size - 1;
- unsigned int i_head = i->head;
- size_t off = i->iov_offset;
- while (1) {
- struct pipe_buffer *b = &pipe->bufs[i_head & p_mask];
- size_t n = off - b->offset;
- if (unroll < n) {
- off -= unroll;
- break;
- }
- unroll -= n;
- if (!unroll && i_head == i->start_head) {
- off = 0;
- break;
- }
- i_head--;
- b = &pipe->bufs[i_head & p_mask];
- off = b->offset + b->len;
- }
- i->iov_offset = off;
- i->head = i_head;
- pipe_truncate(i);
+ if (unroll <= i->iov_offset) {
+ i->iov_offset -= unroll;
return;
}
- if (unlikely(iov_iter_is_discard(i)))
+ unroll -= i->iov_offset;
+ while (1) {
+ size_t n = (--iov)->iov_len;
+ i->nr_segs++;
+ if (unroll <= n) {
+ i->iov = iov;
+ i->iov_offset = n - unroll;
+ return;
+ }
+ unroll -= n;
+ }
+}
+
+static void bvec_revert(struct iov_iter *i, size_t unroll)
+{
+ const struct bio_vec *bvec = i->bvec;
+
+ if (!unroll)
return;
+ if (WARN_ON(unroll > MAX_RW_COUNT))
+ return;
+ i->count += unroll;
if (unroll <= i->iov_offset) {
i->iov_offset -= unroll;
return;
}
unroll -= i->iov_offset;
- if (iov_iter_is_bvec(i)) {
- const struct bio_vec *bvec = i->bvec;
- while (1) {
- size_t n = (--bvec)->bv_len;
- i->nr_segs++;
- if (unroll <= n) {
- i->bvec = bvec;
- i->iov_offset = n - unroll;
- return;
- }
- unroll -= n;
+ while (1) {
+ size_t n = (--bvec)->bv_len;
+ i->nr_segs++;
+ if (unroll <= n) {
+ i->bvec = bvec;
+ i->iov_offset = n - unroll;
+ return;
}
- } else { /* same logics for iovec and kvec */
- const struct iovec *iov = i->iov;
- while (1) {
- size_t n = (--iov)->iov_len;
- i->nr_segs++;
- if (unroll <= n) {
- i->iov = iov;
- i->iov_offset = n - unroll;
- return;
- }
- unroll -= n;
+ unroll -= n;
+ }
+}
+
+static void pipe_revert(struct iov_iter *i, size_t unroll)
+{
+ struct pipe_inode_info *pipe = i->pipe;
+ unsigned int p_mask = pipe->ring_size - 1;
+ unsigned int i_head = i->head;
+ size_t off = i->iov_offset;
+
+ if (!unroll)
+ return;
+ if (WARN_ON(unroll > MAX_RW_COUNT))
+ return;
+
+ while (1) {
+ struct pipe_buffer *b = &pipe->bufs[i_head & p_mask];
+ size_t n = off - b->offset;
+ if (unroll < n) {
+ off -= unroll;
+ break;
+ }
+ unroll -= n;
+ if (!unroll && i_head == i->start_head) {
+ off = 0;
+ break;
}
+ i_head--;
+ b = &pipe->bufs[i_head & p_mask];
+ off = b->offset + b->len;
}
+ i->iov_offset = off;
+ i->head = i_head;
+ pipe_truncate(i);
+}
+
+static void discard_revert(struct iov_iter *i, size_t unroll)
+{
+ if (!unroll)
+ return;
+ if (WARN_ON(unroll > MAX_RW_COUNT))
+ return;
+ i->count += unroll;
}
/*
@@ -2082,7 +2108,7 @@ static const struct iov_iter_ops iovec_iter_ops = {
.type = ITER_IOVEC,
.copy_from_user_atomic = iovec_copy_from_user_atomic,
.advance = iovec_advance,
- .revert = xxx_revert,
+ .revert = iovec_kvec_revert,
.fault_in_readable = iovec_fault_in_readable,
.single_seg_count = xxx_single_seg_count,
.copy_page_to_iter = iovec_copy_page_to_iter,
@@ -2116,7 +2142,7 @@ static const struct iov_iter_ops kvec_iter_ops = {
.type = ITER_KVEC,
.copy_from_user_atomic = kvec_copy_from_user_atomic,
.advance = kvec_advance,
- .revert = xxx_revert,
+ .revert = iovec_kvec_revert,
.fault_in_readable = no_fault_in_readable,
.single_seg_count = xxx_single_seg_count,
.copy_page_to_iter = bkvec_copy_page_to_iter,
@@ -2150,7 +2176,7 @@ static const struct iov_iter_ops bvec_iter_ops = {
.type = ITER_BVEC,
.copy_from_user_atomic = bvec_copy_from_user_atomic,
.advance = bvec_iov_advance,
- .revert = xxx_revert,
+ .revert = bvec_revert,
.fault_in_readable = no_fault_in_readable,
.single_seg_count = xxx_single_seg_count,
.copy_page_to_iter = bkvec_copy_page_to_iter,
@@ -2184,7 +2210,7 @@ static const struct iov_iter_ops pipe_iter_ops = {
.type = ITER_PIPE,
.copy_from_user_atomic = no_copy_from_user_atomic,
.advance = pipe_advance,
- .revert = xxx_revert,
+ .revert = pipe_revert,
.fault_in_readable = no_fault_in_readable,
.single_seg_count = xxx_single_seg_count,
.copy_page_to_iter = pipe_copy_page_to_iter,
@@ -2218,7 +2244,7 @@ static const struct iov_iter_ops discard_iter_ops = {
.type = ITER_DISCARD,
.copy_from_user_atomic = no_copy_from_user_atomic,
.advance = discard_advance,
- .revert = xxx_revert,
+ .revert = discard_revert,
.fault_in_readable = no_fault_in_readable,
.single_seg_count = xxx_single_seg_count,
.copy_page_to_iter = discard_copy_page_to_iter,
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