Equivalent of single-segment iovec. Initialized by iov_iter_ubuf(),
checked for by iter_is_ubuf(), otherwise behaves like ITER_IOVEC
ones.
We are going to expose the things like ->write_iter() et.al. to those
in subsequent commits.
New predicate (user_backed_iter()) that is true for ITER_IOVEC and
ITER_UBUF; places like direct-IO handling should use that for
checking that pages we modify after getting them from iov_iter_get_pages()
would need to be dirtied.
DO NOT assume that replacing iter_is_iovec() with user_backed_iter()
will solve all problems - there's code that uses iter_is_iovec() to
decide how to poke around in iov_iter guts and for that the predicate
replacement obviously won't suffice.
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
block/fops.c | 6 +--
fs/ceph/file.c | 2 +-
fs/cifs/file.c | 2 +-
fs/direct-io.c | 2 +-
fs/fuse/dev.c | 4 +-
fs/fuse/file.c | 2 +-
fs/gfs2/file.c | 2 +-
fs/iomap/direct-io.c | 2 +-
fs/nfs/direct.c | 2 +-
include/linux/uio.h | 26 ++++++++++++
lib/iov_iter.c | 94 ++++++++++++++++++++++++++++++++++----------
mm/shmem.c | 2 +-
12 files changed, 113 insertions(+), 33 deletions(-)
diff --git a/block/fops.c b/block/fops.c
index 6e86931ab847..3e68d69e0ee3 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -69,7 +69,7 @@ static ssize_t __blkdev_direct_IO_simple(struct kiocb *iocb,
if (iov_iter_rw(iter) == READ) {
bio_init(&bio, bdev, vecs, nr_pages, REQ_OP_READ);
- if (iter_is_iovec(iter))
+ if (user_backed_iter(iter))
should_dirty = true;
} else {
bio_init(&bio, bdev, vecs, nr_pages, dio_bio_write_op(iocb));
@@ -199,7 +199,7 @@ static ssize_t __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter,
}
dio->size = 0;
- if (is_read && iter_is_iovec(iter))
+ if (is_read && user_backed_iter(iter))
dio->flags |= DIO_SHOULD_DIRTY;
blk_start_plug(&plug);
@@ -331,7 +331,7 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
dio->size = bio->bi_iter.bi_size;
if (is_read) {
- if (iter_is_iovec(iter)) {
+ if (user_backed_iter(iter)) {
dio->flags |= DIO_SHOULD_DIRTY;
bio_set_pages_dirty(bio);
}
diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index 8c8226c0feac..e132adeeaf16 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -1262,7 +1262,7 @@ ceph_direct_read_write(struct kiocb *iocb, struct iov_iter *iter,
size_t count = iov_iter_count(iter);
loff_t pos = iocb->ki_pos;
bool write = iov_iter_rw(iter) == WRITE;
- bool should_dirty = !write && iter_is_iovec(iter);
+ bool should_dirty = !write && user_backed_iter(iter);
if (write && ceph_snap(file_inode(file)) != CEPH_NOSNAP)
return -EROFS;
diff --git a/fs/cifs/file.c b/fs/cifs/file.c
index 1618e0537d58..4b4129d9a90c 100644
--- a/fs/cifs/file.c
+++ b/fs/cifs/file.c
@@ -4004,7 +4004,7 @@ static ssize_t __cifs_readv(
if (!is_sync_kiocb(iocb))
ctx->iocb = iocb;
- if (iter_is_iovec(to))
+ if (user_backed_iter(to))
ctx->should_dirty = true;
if (direct) {
diff --git a/fs/direct-io.c b/fs/direct-io.c
index 39647eb56904..72237f49ad94 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -1245,7 +1245,7 @@ ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
spin_lock_init(&dio->bio_lock);
dio->refcount = 1;
- dio->should_dirty = iter_is_iovec(iter) && iov_iter_rw(iter) == READ;
+ dio->should_dirty = user_backed_iter(iter) && iov_iter_rw(iter) == READ;
sdio.iter = iter;
sdio.final_block_in_request = end >> blkbits;
diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 0e537e580dc1..8d657c2cd6f7 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1356,7 +1356,7 @@ static ssize_t fuse_dev_read(struct kiocb *iocb, struct iov_iter *to)
if (!fud)
return -EPERM;
- if (!iter_is_iovec(to))
+ if (!user_backed_iter(to))
return -EINVAL;
fuse_copy_init(&cs, 1, to);
@@ -1949,7 +1949,7 @@ static ssize_t fuse_dev_write(struct kiocb *iocb, struct iov_iter *from)
if (!fud)
return -EPERM;
- if (!iter_is_iovec(from))
+ if (!user_backed_iter(from))
return -EINVAL;
fuse_copy_init(&cs, 0, from);
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 00fa861aeead..c982e3afe3b4 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -1465,7 +1465,7 @@ ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
inode_unlock(inode);
}
- io->should_dirty = !write && iter_is_iovec(iter);
+ io->should_dirty = !write && user_backed_iter(iter);
while (count) {
ssize_t nres;
fl_owner_t owner = current->files;
diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index 2cceb193dcd8..48e6cc74fdc1 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -780,7 +780,7 @@ static inline bool should_fault_in_pages(struct iov_iter *i,
if (!count)
return false;
- if (!iter_is_iovec(i))
+ if (!user_backed_iter(i))
return false;
size = PAGE_SIZE;
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 2be8d9e98fbc..322ac9ace23d 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -533,7 +533,7 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
iomi.flags |= IOMAP_NOWAIT;
}
- if (iter_is_iovec(iter))
+ if (user_backed_iter(iter))
dio->flags |= IOMAP_DIO_DIRTY;
} else {
iomi.flags |= IOMAP_WRITE;
diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 4eb2a8380a28..022e1ce63e62 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -478,7 +478,7 @@ ssize_t nfs_file_direct_read(struct kiocb *iocb, struct iov_iter *iter,
if (!is_sync_kiocb(iocb))
dreq->iocb = iocb;
- if (iter_is_iovec(iter))
+ if (user_backed_iter(iter))
dreq->flags = NFS_ODIRECT_SHOULD_DIRTY;
if (!swap)
diff --git a/include/linux/uio.h b/include/linux/uio.h
index 76d305f3d4c2..6ab4260c3d6c 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -26,6 +26,7 @@ enum iter_type {
ITER_PIPE,
ITER_XARRAY,
ITER_DISCARD,
+ ITER_UBUF,
};
struct iov_iter_state {
@@ -38,6 +39,7 @@ struct iov_iter {
u8 iter_type;
bool nofault;
bool data_source;
+ bool user_backed;
size_t iov_offset;
size_t count;
union {
@@ -46,6 +48,7 @@ struct iov_iter {
const struct bio_vec *bvec;
struct xarray *xarray;
struct pipe_inode_info *pipe;
+ void __user *ubuf;
};
union {
unsigned long nr_segs;
@@ -70,6 +73,11 @@ static inline void iov_iter_save_state(struct iov_iter *iter,
state->nr_segs = iter->nr_segs;
}
+static inline bool iter_is_ubuf(const struct iov_iter *i)
+{
+ return iov_iter_type(i) == ITER_UBUF;
+}
+
static inline bool iter_is_iovec(const struct iov_iter *i)
{
return iov_iter_type(i) == ITER_IOVEC;
@@ -105,6 +113,11 @@ static inline unsigned char iov_iter_rw(const struct iov_iter *i)
return i->data_source ? WRITE : READ;
}
+static inline bool user_backed_iter(const struct iov_iter *i)
+{
+ return i->user_backed;
+}
+
/*
* Total number of bytes covered by an iovec.
*
@@ -320,4 +333,17 @@ ssize_t __import_iovec(int type, const struct iovec __user *uvec,
int import_single_range(int type, void __user *buf, size_t len,
struct iovec *iov, struct iov_iter *i);
+static inline void iov_iter_ubuf(struct iov_iter *i, unsigned int direction,
+ void __user *buf, size_t count)
+{
+ WARN_ON(direction & ~(READ | WRITE));
+ *i = (struct iov_iter) {
+ .iter_type = ITER_UBUF,
+ .user_backed = true,
+ .data_source = direction,
+ .ubuf = buf,
+ .count = count
+ };
+}
+
#endif
diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 4c658a25e29c..8275b28e886b 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -16,6 +16,16 @@
#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; \
+ len = n; \
+ base = __p + i->iov_offset; \
+ len -= (STEP); \
+ i->iov_offset += len; \
+ n = len; \
+}
+
/* covers iovec and kvec alike */
#define iterate_iovec(i, n, base, len, off, __p, STEP) { \
size_t off = 0; \
@@ -110,7 +120,12 @@ __out: \
if (unlikely(i->count < n)) \
n = i->count; \
if (likely(n)) { \
- if (likely(iter_is_iovec(i))) { \
+ if (likely(iter_is_ubuf(i))) { \
+ void __user *base; \
+ size_t len; \
+ iterate_buf(i, n, base, len, off, \
+ i->ubuf, (I)) \
+ } else if (likely(iter_is_iovec(i))) { \
const struct iovec *iov = i->iov; \
void __user *base; \
size_t len; \
@@ -275,7 +290,11 @@ static size_t copy_page_to_iter_pipe(struct page *page, size_t offset, size_t by
*/
size_t fault_in_iov_iter_readable(const struct iov_iter *i, size_t size)
{
- if (iter_is_iovec(i)) {
+ if (iter_is_ubuf(i)) {
+ size_t n = min(size, iov_iter_count(i));
+ n -= fault_in_readable(i->ubuf + i->iov_offset, n);
+ return size - n;
+ } else if (iter_is_iovec(i)) {
size_t count = min(size, iov_iter_count(i));
const struct iovec *p;
size_t skip;
@@ -314,7 +333,11 @@ EXPORT_SYMBOL(fault_in_iov_iter_readable);
*/
size_t fault_in_iov_iter_writeable(const struct iov_iter *i, size_t size)
{
- if (iter_is_iovec(i)) {
+ if (iter_is_ubuf(i)) {
+ size_t n = min(size, iov_iter_count(i));
+ n -= fault_in_safe_writeable(i->ubuf + i->iov_offset, n);
+ return size - n;
+ } else if (iter_is_iovec(i)) {
size_t count = min(size, iov_iter_count(i));
const struct iovec *p;
size_t skip;
@@ -345,6 +368,7 @@ void iov_iter_init(struct iov_iter *i, unsigned int direction,
*i = (struct iov_iter) {
.iter_type = ITER_IOVEC,
.nofault = false,
+ .user_backed = true,
.data_source = direction,
.iov = iov,
.nr_segs = nr_segs,
@@ -494,7 +518,7 @@ size_t _copy_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
{
if (unlikely(iov_iter_is_pipe(i)))
return copy_pipe_to_iter(addr, bytes, i);
- if (iter_is_iovec(i))
+ if (user_backed_iter(i))
might_fault();
iterate_and_advance(i, bytes, base, len, off,
copyout(base, addr + off, len),
@@ -576,7 +600,7 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
{
if (unlikely(iov_iter_is_pipe(i)))
return copy_mc_pipe_to_iter(addr, bytes, i);
- if (iter_is_iovec(i))
+ if (user_backed_iter(i))
might_fault();
__iterate_and_advance(i, bytes, base, len, off,
copyout_mc(base, addr + off, len),
@@ -594,7 +618,7 @@ size_t _copy_from_iter(void *addr, size_t bytes, struct iov_iter *i)
WARN_ON(1);
return 0;
}
- if (iter_is_iovec(i))
+ if (user_backed_iter(i))
might_fault();
iterate_and_advance(i, bytes, base, len, off,
copyin(addr + off, base, len),
@@ -882,16 +906,16 @@ void iov_iter_advance(struct iov_iter *i, size_t size)
{
if (unlikely(i->count < size))
size = i->count;
- if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) {
+ if (likely(iter_is_ubuf(i)) || unlikely(iov_iter_is_xarray(i))) {
+ i->iov_offset += size;
+ i->count -= size;
+ } else if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i))) {
/* iovec and kvec have identical layouts */
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 (unlikely(iov_iter_is_xarray(i))) {
- i->iov_offset += size;
- i->count -= size;
} else if (iov_iter_is_discard(i)) {
i->count -= size;
}
@@ -938,7 +962,7 @@ void iov_iter_revert(struct iov_iter *i, size_t unroll)
return;
}
unroll -= i->iov_offset;
- if (iov_iter_is_xarray(i)) {
+ if (iov_iter_is_xarray(i) || iter_is_ubuf(i)) {
BUG(); /* We should never go beyond the start of the specified
* range since we might then be straying into pages that
* aren't pinned.
@@ -1129,6 +1153,13 @@ static unsigned long iov_iter_alignment_bvec(const struct iov_iter *i)
unsigned long iov_iter_alignment(const struct iov_iter *i)
{
+ if (likely(iter_is_ubuf(i))) {
+ size_t size = i->count;
+ if (size)
+ return ((unsigned long)i->ubuf + i->iov_offset) | size;
+ return 0;
+ }
+
/* iovec and kvec have identical layouts */
if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
return iov_iter_alignment_iovec(i);
@@ -1159,6 +1190,9 @@ unsigned long iov_iter_gap_alignment(const struct iov_iter *i)
size_t size = i->count;
unsigned k;
+ if (iter_is_ubuf(i))
+ return 0;
+
if (WARN_ON(!iter_is_iovec(i)))
return ~0U;
@@ -1287,7 +1321,19 @@ static ssize_t iter_xarray_get_pages(struct iov_iter *i,
return actual;
}
-/* must be done on non-empty ITER_IOVEC one */
+static unsigned long found_ubuf_segment(unsigned long addr,
+ size_t len,
+ size_t *size, size_t *start,
+ unsigned maxpages)
+{
+ len += (*start = addr % PAGE_SIZE);
+ if (len > maxpages * PAGE_SIZE)
+ len = maxpages * PAGE_SIZE;
+ *size = len;
+ return addr & PAGE_MASK;
+}
+
+/* must be done on non-empty ITER_UBUF or ITER_IOVEC one */
static unsigned long first_iovec_segment(const struct iov_iter *i,
size_t *size, size_t *start,
size_t maxsize, unsigned maxpages)
@@ -1295,6 +1341,11 @@ static unsigned long first_iovec_segment(const struct iov_iter *i,
size_t skip;
long k;
+ if (iter_is_ubuf(i)) {
+ unsigned long addr = (unsigned long)i->ubuf + i->iov_offset;
+ return found_ubuf_segment(addr, maxsize, size, start, maxpages);
+ }
+
for (k = 0, skip = i->iov_offset; k < i->nr_segs; k++, skip = 0) {
unsigned long addr = (unsigned long)i->iov[k].iov_base + skip;
size_t len = i->iov[k].iov_len - skip;
@@ -1303,11 +1354,7 @@ static unsigned long first_iovec_segment(const struct iov_iter *i,
continue;
if (len > maxsize)
len = maxsize;
- len += (*start = addr % PAGE_SIZE);
- if (len > maxpages * PAGE_SIZE)
- len = maxpages * PAGE_SIZE;
- *size = len;
- return addr & PAGE_MASK;
+ return found_ubuf_segment(addr, len, size, start, maxpages);
}
BUG(); // if it had been empty, we wouldn't get called
}
@@ -1344,7 +1391,7 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
if (!maxsize)
return 0;
- if (likely(iter_is_iovec(i))) {
+ if (likely(user_backed_iter(i))) {
unsigned int gup_flags = 0;
unsigned long addr;
@@ -1470,7 +1517,7 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
if (!maxsize)
return 0;
- if (likely(iter_is_iovec(i))) {
+ if (likely(user_backed_iter(i))) {
unsigned int gup_flags = 0;
unsigned long addr;
@@ -1624,6 +1671,11 @@ int iov_iter_npages(const struct iov_iter *i, int maxpages)
{
if (unlikely(!i->count))
return 0;
+ if (likely(iter_is_ubuf(i))) {
+ unsigned offs = offset_in_page(i->ubuf + i->iov_offset);
+ int npages = DIV_ROUND_UP(offs + i->count, PAGE_SIZE);
+ return min(npages, maxpages);
+ }
/* iovec and kvec have identical layouts */
if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
return iov_npages(i, maxpages);
@@ -1862,10 +1914,12 @@ EXPORT_SYMBOL(import_single_range);
void iov_iter_restore(struct iov_iter *i, struct iov_iter_state *state)
{
if (WARN_ON_ONCE(!iov_iter_is_bvec(i) && !iter_is_iovec(i)) &&
- !iov_iter_is_kvec(i))
+ !iov_iter_is_kvec(i) && !iter_is_ubuf(i))
return;
i->iov_offset = state->iov_offset;
i->count = state->count;
+ if (iter_is_ubuf(i))
+ return;
/*
* For the *vec iters, nr_segs + iov is constant - if we increment
* the vec, then we also decrement the nr_segs count. Hence we don't
diff --git a/mm/shmem.c b/mm/shmem.c
index a6f565308133..6b83f3971795 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2603,7 +2603,7 @@ static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
ret = copy_page_to_iter(page, offset, nr, to);
put_page(page);
- } else if (iter_is_iovec(to)) {
+ } else if (!user_backed_iter(to)) {
/*
* Copy to user tends to be so well optimized, but
* clear_user() not so much, that it is noticeably
--
2.30.2
