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author | Linus Torvalds <torvalds@linux-foundation.org> | 2023-06-26 20:52:12 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2023-06-26 20:52:12 +0200 |
commit | 3eccc0c886b1796f95a289c9d127c8ca1a254bd5 (patch) | |
tree | 021761894d246df22d53e1c64810f6cbf3ece716 /lib | |
parent | Merge tag 'for-6.5-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdav... (diff) | |
parent | splice: kdoc for filemap_splice_read() and copy_splice_read() (diff) | |
download | linux-3eccc0c886b1796f95a289c9d127c8ca1a254bd5.tar.xz linux-3eccc0c886b1796f95a289c9d127c8ca1a254bd5.zip |
Merge tag 'for-6.5/splice-2023-06-23' of git://git.kernel.dk/linux
Pull splice updates from Jens Axboe:
"This kills off ITER_PIPE to avoid a race between truncate,
iov_iter_revert() on the pipe and an as-yet incomplete DMA to a bio
with unpinned/unref'ed pages from an O_DIRECT splice read. This causes
memory corruption.
Instead, we either use (a) filemap_splice_read(), which invokes the
buffered file reading code and splices from the pagecache into the
pipe; (b) copy_splice_read(), which bulk-allocates a buffer, reads
into it and then pushes the filled pages into the pipe; or (c) handle
it in filesystem-specific code.
Summary:
- Rename direct_splice_read() to copy_splice_read()
- Simplify the calculations for the number of pages to be reclaimed
in copy_splice_read()
- Turn do_splice_to() into a helper, vfs_splice_read(), so that it
can be used by overlayfs and coda to perform the checks on the
lower fs
- Make vfs_splice_read() jump to copy_splice_read() to handle
direct-I/O and DAX
- Provide shmem with its own splice_read to handle non-existent pages
in the pagecache. We don't want a ->read_folio() as we don't want
to populate holes, but filemap_get_pages() requires it
- Provide overlayfs with its own splice_read to call down to a lower
layer as overlayfs doesn't provide ->read_folio()
- Provide coda with its own splice_read to call down to a lower layer
as coda doesn't provide ->read_folio()
- Direct ->splice_read to copy_splice_read() in tty, procfs, kernfs
and random files as they just copy to the output buffer and don't
splice pages
- Provide wrappers for afs, ceph, ecryptfs, ext4, f2fs, nfs, ntfs3,
ocfs2, orangefs, xfs and zonefs to do locking and/or revalidation
- Make cifs use filemap_splice_read()
- Replace pointers to generic_file_splice_read() with pointers to
filemap_splice_read() as DIO and DAX are handled in the caller;
filesystems can still provide their own alternate ->splice_read()
op
- Remove generic_file_splice_read()
- Remove ITER_PIPE and its paraphernalia as generic_file_splice_read
was the only user"
* tag 'for-6.5/splice-2023-06-23' of git://git.kernel.dk/linux: (31 commits)
splice: kdoc for filemap_splice_read() and copy_splice_read()
iov_iter: Kill ITER_PIPE
splice: Remove generic_file_splice_read()
splice: Use filemap_splice_read() instead of generic_file_splice_read()
cifs: Use filemap_splice_read()
trace: Convert trace/seq to use copy_splice_read()
zonefs: Provide a splice-read wrapper
xfs: Provide a splice-read wrapper
orangefs: Provide a splice-read wrapper
ocfs2: Provide a splice-read wrapper
ntfs3: Provide a splice-read wrapper
nfs: Provide a splice-read wrapper
f2fs: Provide a splice-read wrapper
ext4: Provide a splice-read wrapper
ecryptfs: Provide a splice-read wrapper
ceph: Provide a splice-read wrapper
afs: Provide a splice-read wrapper
9p: Add splice_read wrapper
net: Make sock_splice_read() use copy_splice_read() by default
tty, proc, kernfs, random: Use copy_splice_read()
...
Diffstat (limited to 'lib')
-rw-r--r-- | lib/iov_iter.c | 431 |
1 files changed, 3 insertions, 428 deletions
diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 960223ed9199..f18138e0292a 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -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), |