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iov_iter: Kill ITER_PIPE

Browse Source 
The ITER_PIPE-type iterator was only used by generic_file_splice_read() and
that has been replaced and removed.  This leaves ITER_PIPE unused - so
remove it too.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
cc: Jens Axboe <axboe@kernel.dk>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: David Hildenbrand <david@redhat.com>
cc: John Hubbard <jhubbard@nvidia.com>
cc: linux-mm@kvack.org
cc: linux-block@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20230522135018.2742245-31-dhowells@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
David Howells 2023-05-22 14:50:17 +01:00 committed by Jens Axboe
parent c6585011bc
commit 3fc40265ae
3 changed files with 4 additions and 444 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

14
include/linux/uio.h
View File

@ -11,7 +11,6 @@
#include <uapi/linux/uio.h>
struct page;
struct pipe_inode_info;
typedef unsigned int __bitwise iov_iter_extraction_t;
@ -25,7 +24,6 @@ enum iter_type {
ITER_IOVEC,
ITER_KVEC,
ITER_BVEC,
ITER_PIPE,
ITER_XARRAY,
ITER_DISCARD,
ITER_UBUF,
@ -74,7 +72,6 @@ struct iov_iter {
const struct kvec *kvec;
const struct bio_vec *bvec;
struct xarray *xarray;
struct pipe_inode_info *pipe;
void __user *ubuf;
};
size_t count;
@ -82,10 +79,6 @@ struct iov_iter {
};
union {
unsigned long nr_segs;
struct {
unsigned int head;
unsigned int start_head;
};
loff_t xarray_start;
};
};
@ -133,11 +126,6 @@ static inline bool iov_iter_is_bvec(const struct iov_iter *i)
return iov_iter_type(i) == ITER_BVEC;
}
static inline bool iov_iter_is_pipe(const struct iov_iter *i)
{
return iov_iter_type(i) == ITER_PIPE;
}
static inline bool iov_iter_is_discard(const struct iov_iter *i)
{
return iov_iter_type(i) == ITER_DISCARD;
@ -286,8 +274,6 @@ void iov_iter_kvec(struct iov_iter *i, unsigned int direction, const struct kvec
unsigned long nr_segs, size_t count);
void iov_iter_bvec(struct iov_iter *i, unsigned int direction, const struct bio_vec *bvec,
unsigned long nr_segs, size_t count);
void iov_iter_pipe(struct iov_iter *i, unsigned int direction, struct pipe_inode_info *pipe,
size_t count);
void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count);
void iov_iter_xarray(struct iov_iter *i, unsigned int direction, struct xarray *xarray,
loff_t start, size_t count);

431
lib/iov_iter.c
View File

@ -14,8 +14,6 @@
#include <linux/scatterlist.h>
#include <linux/instrumented.h>
#define PIPE_PARANOIA /* for now */
/* covers ubuf and kbuf alike */
#define iterate_buf(i, n, base, len, off, __p, STEP) { \
size_t __maybe_unused off = 0; \
@ -198,150 +196,6 @@ static int copyin(void *to, const void __user *from, size_t n)
return res;
}
#ifdef PIPE_PARANOIA
static bool sanity(const struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
unsigned int p_head = pipe->head;
unsigned int p_tail = pipe->tail;
unsigned int p_occupancy = pipe_occupancy(p_head, p_tail);
unsigned int i_head = i->head;
unsigned int idx;
if (i->last_offset) {
struct pipe_buffer *p;
if (unlikely(p_occupancy == 0))
goto Bad; // pipe must be non-empty
if (unlikely(i_head != p_head - 1))
goto Bad; // must be at the last buffer...
p = pipe_buf(pipe, i_head);
if (unlikely(p->offset + p->len != abs(i->last_offset)))
goto Bad; // ... at the end of segment
} else {
if (i_head != p_head)
goto Bad; // must be right after the last buffer
}
return true;
Bad:
printk(KERN_ERR "idx = %d, offset = %d\n", i_head, i->last_offset);
printk(KERN_ERR "head = %d, tail = %d, buffers = %d\n",
p_head, p_tail, pipe->ring_size);
for (idx = 0; idx < pipe->ring_size; idx++)
printk(KERN_ERR "[%p %p %d %d]\n",
pipe->bufs[idx].ops,
pipe->bufs[idx].page,
pipe->bufs[idx].offset,
pipe->bufs[idx].len);
WARN_ON(1);
return false;
}
#else
#define sanity(i) true
#endif
static struct page *push_anon(struct pipe_inode_info *pipe, unsigned size)
{
struct page *page = alloc_page(GFP_USER);
if (page) {
struct pipe_buffer *buf = pipe_buf(pipe, pipe->head++);
*buf = (struct pipe_buffer) {
.ops = &default_pipe_buf_ops,
.page = page,
.offset = 0,
.len = size
};
}
return page;
}
static void push_page(struct pipe_inode_info *pipe, struct page *page,
unsigned int offset, unsigned int size)
{
struct pipe_buffer *buf = pipe_buf(pipe, pipe->head++);
*buf = (struct pipe_buffer) {
.ops = &page_cache_pipe_buf_ops,
.page = page,
.offset = offset,
.len = size
};
get_page(page);
}
static inline int last_offset(const struct pipe_buffer *buf)
{
if (buf->ops == &default_pipe_buf_ops)
return buf->len; // buf->offset is 0 for those
else
return -(buf->offset + buf->len);
}
static struct page *append_pipe(struct iov_iter *i, size_t size,
unsigned int *off)
{
struct pipe_inode_info *pipe = i->pipe;
int offset = i->last_offset;
struct pipe_buffer *buf;
struct page *page;
if (offset > 0 && offset < PAGE_SIZE) {
// some space in the last buffer; add to it
buf = pipe_buf(pipe, pipe->head - 1);
size = min_t(size_t, size, PAGE_SIZE - offset);
buf->len += size;
i->last_offset += size;
i->count -= size;
*off = offset;
return buf->page;
}
// OK, we need a new buffer
*off = 0;
size = min_t(size_t, size, PAGE_SIZE);
if (pipe_full(pipe->head, pipe->tail, pipe->max_usage))
return NULL;
page = push_anon(pipe, size);
if (!page)
return NULL;
i->head = pipe->head - 1;
i->last_offset = size;
i->count -= size;
return page;
}
static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t bytes,
struct iov_iter *i)
{
struct pipe_inode_info *pipe = i->pipe;
unsigned int head = pipe->head;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
if (!sanity(i))
return 0;
if (offset && i->last_offset == -offset) { // could we merge it?
struct pipe_buffer *buf = pipe_buf(pipe, head - 1);
if (buf->page == page) {
buf->len += bytes;
i->last_offset -= bytes;
i->count -= bytes;
return bytes;
}
}
if (pipe_full(pipe->head, pipe->tail, pipe->max_usage))
return 0;
push_page(pipe, page, offset, bytes);
i->last_offset = -(offset + bytes);
i->head = head;
i->count -= bytes;
return bytes;
}
/*
* fault_in_iov_iter_readable - fault in iov iterator for reading
* @i: iterator
@ -446,46 +300,6 @@ void iov_iter_init(struct iov_iter *i, unsigned int direction,
}
EXPORT_SYMBOL(iov_iter_init);
// returns the offset in partial buffer (if any)
static inline unsigned int pipe_npages(const struct iov_iter *i, int *npages)
{
struct pipe_inode_info *pipe = i->pipe;
int used = pipe->head - pipe->tail;
int off = i->last_offset;
*npages = max((int)pipe->max_usage - used, 0);
if (off > 0 && off < PAGE_SIZE) { // anon and not full
(*npages)++;
return off;
}
return 0;
}
static size_t copy_pipe_to_iter(const void *addr, size_t bytes,
struct iov_iter *i)
{
unsigned int off, chunk;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
if (!sanity(i))
return 0;
for (size_t n = bytes; n; n -= chunk) {
struct page *page = append_pipe(i, n, &off);
chunk = min_t(size_t, n, PAGE_SIZE - off);
if (!page)
return bytes - n;
memcpy_to_page(page, off, addr, chunk);
addr += chunk;
}
return bytes;
}
static __wsum csum_and_memcpy(void *to, const void *from, size_t len,
__wsum sum, size_t off)
{
@ -493,44 +307,10 @@ static __wsum csum_and_memcpy(void *to, const void *from, size_t len,
return csum_block_add(sum, next, off);
}
static size_t csum_and_copy_to_pipe_iter(const void *addr, size_t bytes,
struct iov_iter *i, __wsum *sump)
{
__wsum sum = *sump;
size_t off = 0;
unsigned int chunk, r;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
if (!sanity(i))
return 0;
while (bytes) {
struct page *page = append_pipe(i, bytes, &r);
char *p;
if (!page)
break;
chunk = min_t(size_t, bytes, PAGE_SIZE - r);
p = kmap_local_page(page);
sum = csum_and_memcpy(p + r, addr + off, chunk, sum, off);
kunmap_local(p);
off += chunk;
bytes -= chunk;
}
*sump = sum;
return off;
}
size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
{
if (WARN_ON_ONCE(i->data_source))
return 0;
if (unlikely(iov_iter_is_pipe(i)))
return copy_pipe_to_iter(addr, bytes, i);
if (user_backed_iter(i))
might_fault();
iterate_and_advance(i, bytes, base, len, off,
@ -552,42 +332,6 @@ static int copyout_mc(void __user *to, const void *from, size_t n)
return n;
}
static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes,
struct iov_iter *i)
{
size_t xfer = 0;
unsigned int off, chunk;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
if (!sanity(i))
return 0;
while (bytes) {
struct page *page = append_pipe(i, bytes, &off);
unsigned long rem;
char *p;
if (!page)
break;
chunk = min_t(size_t, bytes, PAGE_SIZE - off);
p = kmap_local_page(page);
rem = copy_mc_to_kernel(p + off, addr + xfer, chunk);
chunk -= rem;
kunmap_local(p);
xfer += chunk;
bytes -= chunk;
if (rem) {
iov_iter_revert(i, rem);
break;
}
}
return xfer;
}
/**
* _copy_mc_to_iter - copy to iter with source memory error exception handling
* @addr: source kernel address
@ -607,9 +351,8 @@ static size_t copy_mc_pipe_to_iter(const void *addr, size_t bytes,
* alignment and poison alignment assumptions to avoid re-triggering
* hardware exceptions.
*
* * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies.
* Compare to copy_to_iter() where only ITER_IOVEC attempts might return
* a short copy.
* * ITER_KVEC and ITER_BVEC can return short copies. Compare to
* copy_to_iter() where only ITER_IOVEC attempts might return a short copy.
*
* Return: number of bytes copied (may be %0)
*/
@ -617,8 +360,6 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
{
if (WARN_ON_ONCE(i->data_source))
return 0;
if (unlikely(iov_iter_is_pipe(i)))
return copy_mc_pipe_to_iter(addr, bytes, i);
if (user_backed_iter(i))
might_fault();
__iterate_and_advance(i, bytes, base, len, off,
@ -732,8 +473,6 @@ size_t copy_page_to_iter(struct page *page, size_t offset, size_t bytes,
return 0;
if (WARN_ON_ONCE(i->data_source))
return 0;
if (unlikely(iov_iter_is_pipe(i)))
return copy_page_to_iter_pipe(page, offset, bytes, i);
page += offset / PAGE_SIZE; // first subpage
offset %= PAGE_SIZE;
while (1) {
@ -764,8 +503,6 @@ size_t copy_page_to_iter_nofault(struct page *page, unsigned offset, size_t byte
return 0;
if (WARN_ON_ONCE(i->data_source))
return 0;
if (unlikely(iov_iter_is_pipe(i)))
return copy_page_to_iter_pipe(page, offset, bytes, i);
page += offset / PAGE_SIZE; // first subpage
offset %= PAGE_SIZE;
while (1) {
@ -818,36 +555,8 @@ size_t copy_page_from_iter(struct page *page, size_t offset, size_t bytes,
}
EXPORT_SYMBOL(copy_page_from_iter);
static size_t pipe_zero(size_t bytes, struct iov_iter *i)
{
unsigned int chunk, off;
if (unlikely(bytes > i->count))
bytes = i->count;
if (unlikely(!bytes))
return 0;
if (!sanity(i))
return 0;
for (size_t n = bytes; n; n -= chunk) {
struct page *page = append_pipe(i, n, &off);
char *p;
if (!page)
return bytes - n;
chunk = min_t(size_t, n, PAGE_SIZE - off);
p = kmap_local_page(page);
memset(p + off, 0, chunk);
kunmap_local(p);
}
return bytes;
}
size_t iov_iter_zero(size_t bytes, struct iov_iter *i)
{
if (unlikely(iov_iter_is_pipe(i)))
return pipe_zero(bytes, i);
iterate_and_advance(i, bytes, base, len, count,
clear_user(base, len),
memset(base, 0, len)
@ -878,32 +587,6 @@ size_t copy_page_from_iter_atomic(struct page *page, unsigned offset, size_t byt
}
EXPORT_SYMBOL(copy_page_from_iter_atomic);
static void pipe_advance(struct iov_iter *i, size_t size)
{
struct pipe_inode_info *pipe = i->pipe;
int off = i->last_offset;
if (!off && !size) {
pipe_discard_from(pipe, i->start_head); // discard everything
return;
}
i->count -= size;
while (1) {
struct pipe_buffer *buf = pipe_buf(pipe, i->head);
if (off) /* make it relative to the beginning of buffer */
size += abs(off) - buf->offset;
if (size <= buf->len) {
buf->len = size;
i->last_offset = last_offset(buf);
break;
}
size -= buf->len;
i->head++;
off = 0;
}
pipe_discard_from(pipe, i->head + 1); // discard everything past this one
}
static void iov_iter_bvec_advance(struct iov_iter *i, size_t size)
{
const struct bio_vec *bvec, *end;
@ -955,8 +638,6 @@ void iov_iter_advance(struct iov_iter *i, size_t size)
iov_iter_iovec_advance(i, size);
} else if (iov_iter_is_bvec(i)) {
iov_iter_bvec_advance(i, size);
} else if (iov_iter_is_pipe(i)) {
pipe_advance(i, size);
} else if (iov_iter_is_discard(i)) {
i->count -= size;
}
@ -970,26 +651,6 @@ void iov_iter_revert(struct iov_iter *i, size_t unroll)
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 head = pipe->head;
while (head > i->start_head) {
struct pipe_buffer *b = pipe_buf(pipe, --head);
if (unroll < b->len) {
b->len -= unroll;
i->last_offset = last_offset(b);
i->head = head;
return;
}
unroll -= b->len;
pipe_buf_release(pipe, b);
pipe->head--;
}
i->last_offset = 0;
i->head = head;
return;
}
if (unlikely(iov_iter_is_discard(i)))
return;
if (unroll <= i->iov_offset) {
@ -1079,24 +740,6 @@ void iov_iter_bvec(struct iov_iter *i, unsigned int direction,
}
EXPORT_SYMBOL(iov_iter_bvec);
void iov_iter_pipe(struct iov_iter *i, unsigned int direction,
struct pipe_inode_info *pipe,
size_t count)
{
BUG_ON(direction != READ);
WARN_ON(pipe_full(pipe->head, pipe->tail, pipe->ring_size));
*i = (struct iov_iter){
.iter_type = ITER_PIPE,
.data_source = false,
.pipe = pipe,
.head = pipe->head,
.start_head = pipe->head,
.last_offset = 0,
.count = count
};
}
EXPORT_SYMBOL(iov_iter_pipe);
/**
* iov_iter_xarray - Initialise an I/O iterator to use the pages in an xarray
* @i: The iterator to initialise.
@ -1224,19 +867,6 @@ bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
if (iov_iter_is_bvec(i))
return iov_iter_aligned_bvec(i, addr_mask, len_mask);
if (iov_iter_is_pipe(i)) {
size_t size = i->count;
if (size & len_mask)
return false;
if (size && i->last_offset > 0) {
if (i->last_offset & addr_mask)
return false;
}
return true;
}
if (iov_iter_is_xarray(i)) {
if (i->count & len_mask)
return false;
@ -1307,14 +937,6 @@ unsigned long iov_iter_alignment(const struct iov_iter *i)
if (iov_iter_is_bvec(i))
return iov_iter_alignment_bvec(i);
if (iov_iter_is_pipe(i)) {
size_t size = i->count;
if (size && i->last_offset > 0)
return size | i->last_offset;
return size;
}
if (iov_iter_is_xarray(i))
return (i->xarray_start + i->iov_offset) | i->count;
@ -1367,36 +989,6 @@ static int want_pages_array(struct page ***res, size_t size,
return count;
}
static ssize_t pipe_get_pages(struct iov_iter *i,
struct page ***pages, size_t maxsize, unsigned maxpages,
size_t *start)
{
unsigned int npages, count, off, chunk;
struct page **p;
size_t left;
if (!sanity(i))
return -EFAULT;
*start = off = pipe_npages(i, &npages);
if (!npages)
return -EFAULT;
count = want_pages_array(pages, maxsize, off, min(npages, maxpages));
if (!count)
return -ENOMEM;
p = *pages;
for (npages = 0, left = maxsize ; npages < count; npages++, left -= chunk) {
struct page *page = append_pipe(i, left, &off);
if (!page)
break;
chunk = min_t(size_t, left, PAGE_SIZE - off);
get_page(*p++ = page);
}
if (!npages)
return -EFAULT;
return maxsize - left;
}
static ssize_t iter_xarray_populate_pages(struct page **pages, struct xarray *xa,
pgoff_t index, unsigned int nr_pages)
{
@ -1547,8 +1139,6 @@ static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
}
return maxsize;
}
if (iov_iter_is_pipe(i))
return pipe_get_pages(i, pages, maxsize, maxpages, start);
if (iov_iter_is_xarray(i))
return iter_xarray_get_pages(i, pages, maxsize, maxpages, start);
return -EFAULT;
@ -1638,9 +1228,7 @@ size_t csum_and_copy_to_iter(const void *addr, size_t bytes, void *_csstate,
}
sum = csum_shift(csstate->csum, csstate->off);
if (unlikely(iov_iter_is_pipe(i)))
bytes = csum_and_copy_to_pipe_iter(addr, bytes, i, &sum);
else iterate_and_advance(i, bytes, base, len, off, ({
iterate_and_advance(i, bytes, base, len, off, ({
next = csum_and_copy_to_user(addr + off, base, len);
sum = csum_block_add(sum, next, off);
next ? 0 : len;
@ -1725,15 +1313,6 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages)
return iov_npages(i, maxpages);
if (iov_iter_is_bvec(i))
return bvec_npages(i, maxpages);
if (iov_iter_is_pipe(i)) {
int npages;
if (!sanity(i))
return 0;
pipe_npages(i, &npages);
return min(npages, maxpages);
}
if (iov_iter_is_xarray(i)) {
unsigned offset = (i->xarray_start + i->iov_offset) % PAGE_SIZE;
int npages = DIV_ROUND_UP(offset + i->count, PAGE_SIZE);
@ -1746,10 +1325,6 @@ EXPORT_SYMBOL(iov_iter_npages);
const void *dup_iter(struct iov_iter *new, struct iov_iter *old, gfp_t flags)
{
*new = *old;
if (unlikely(iov_iter_is_pipe(new))) {
WARN_ON(1);
return NULL;
}
if (iov_iter_is_bvec(new))
return new->bvec = kmemdup(new->bvec,
new->nr_segs * sizeof(struct bio_vec),

3
mm/filemap.c
View File

@ -2687,8 +2687,7 @@ ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter,
if (unlikely(iocb->ki_pos >= i_size_read(inode)))
break;
error = filemap_get_pages(iocb, iter->count, &fbatch,
iov_iter_is_pipe(iter));
error = filemap_get_pages(iocb, iter->count, &fbatch, false);
if (error < 0)
break;