| Message ID | 20241105155235.460088-3-hch@lst.de (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [1/2] block: remove bio_add_hw_folio | expand |
On 05/11/24 04:52PM, Christoph Hellwig wrote: >__bio_iov_iter_get_pages currently open codes adding pages to the bio, >which duplicates a lot of code from bio_add_page. Add a lower level >bio_do_add_page helpers that passes down the same_page output argument >so that __bio_iov_iter_get_pages can reuse the code and also check >for the error return from it - while no error should happen due to >how the bvec space is used for the pin_user_space result I'd rather >be safe than sorry and actually check for these impossible errors. > >Signed-off-by: Christoph Hellwig <hch@lst.de> >--- > block/bio.c | 66 ++++++++++++++++++++++++----------------------------- > 1 file changed, 30 insertions(+), 36 deletions(-) > >diff --git a/block/bio.c b/block/bio.c >index 1f6ac44b4881..bc3bca5f0686 100644 >--- a/block/bio.c >+++ b/block/bio.c >@@ -1063,20 +1063,9 @@ void __bio_add_page(struct bio *bio, struct page *page, > } > EXPORT_SYMBOL_GPL(__bio_add_page); > >-/** >- * bio_add_page - attempt to add page(s) to bio >- * @bio: destination bio >- * @page: start page to add >- * @len: vec entry length, may cross pages >- * @offset: vec entry offset relative to @page, may cross pages >- * >- * Attempt to add page(s) to the bio_vec maplist. This will only fail >- * if either bio->bi_vcnt == bio->bi_max_vecs or it's a cloned bio. >- */ >-int bio_add_page(struct bio *bio, struct page *page, >- unsigned int len, unsigned int offset) >+static int bio_do_add_page(struct bio *bio, struct page *page, >+ unsigned int len, unsigned int offset, bool *same_page) As we are passing length within a folio, values will reach near UINT_MAX. It will be better to make len and offset as size_t, also to add a check like : if (len > UINT_MAX || offset > UINT_MAX) return 0; > { >- bool same_page = false; nit: extra line got added
On Wed, Nov 06, 2024 at 03:33:38PM +0530, Kundan Kumar wrote: >> -int bio_add_page(struct bio *bio, struct page *page, >> - unsigned int len, unsigned int offset) >> +static int bio_do_add_page(struct bio *bio, struct page *page, >> + unsigned int len, unsigned int offset, bool *same_page) > > As we are passing length within a folio, values will reach near UINT_MAX. > It will be better to make len and offset as size_t, also to add a check like : > if (len > UINT_MAX || offset > UINT_MAX) > return 0; Not sure what the point is. IFF we get folio sizes overflowing an unsigned int we'll have a massive problem as it will overflow the bv_offset and bv_len fields. So we'd need to address that first before doing anything else. >> { >> - bool same_page = false; > > nit: extra line got added Yes, the previous code was missing the empty line after the variable declaration, so this got fixed.
On 07/11/24 08:20AM, Christoph Hellwig wrote: >On Wed, Nov 06, 2024 at 03:33:38PM +0530, Kundan Kumar wrote: >>> -int bio_add_page(struct bio *bio, struct page *page, >>> - unsigned int len, unsigned int offset) >>> +static int bio_do_add_page(struct bio *bio, struct page *page, >>> + unsigned int len, unsigned int offset, bool *same_page) >> >> As we are passing length within a folio, values will reach near UINT_MAX. >> It will be better to make len and offset as size_t, also to add a check like : >> if (len > UINT_MAX || offset > UINT_MAX) >> return 0; > >Not sure what the point is. IFF we get folio sizes overflowing an >unsigned int we'll have a massive problem as it will overflow the >bv_offset and bv_len fields. So we'd need to address that first before >doing anything else. In my opinion, there isn't a current use case where it overflows, but its better to include a check for the future. WARN_ON is also an option as used in bio_add_folio_nofail() > >>> { >>> - bool same_page = false; >> >> nit: extra line got added > >Yes, the previous code was missing the empty line after the variable >declaration, so this got fixed. > Actually the extra line got introduced at the beginning of function definition of bio_do_add_page(). Otherwise the code looks good. Reviewed-by: Kundan Kumar <kundan.kumar@samsung.com>
diff --git a/block/bio.c b/block/bio.c index 1f6ac44b4881..bc3bca5f0686 100644 --- a/block/bio.c +++ b/block/bio.c @@ -1063,20 +1063,9 @@ void __bio_add_page(struct bio *bio, struct page *page, } EXPORT_SYMBOL_GPL(__bio_add_page); -/** - * bio_add_page - attempt to add page(s) to bio - * @bio: destination bio - * @page: start page to add - * @len: vec entry length, may cross pages - * @offset: vec entry offset relative to @page, may cross pages - * - * Attempt to add page(s) to the bio_vec maplist. This will only fail - * if either bio->bi_vcnt == bio->bi_max_vecs or it's a cloned bio. - */ -int bio_add_page(struct bio *bio, struct page *page, - unsigned int len, unsigned int offset) +static int bio_do_add_page(struct bio *bio, struct page *page, + unsigned int len, unsigned int offset, bool *same_page) { - bool same_page = false; if (WARN_ON_ONCE(bio_flagged(bio, BIO_CLONED))) return 0; @@ -1085,7 +1074,7 @@ int bio_add_page(struct bio *bio, struct page *page, if (bio->bi_vcnt > 0 && bvec_try_merge_page(&bio->bi_io_vec[bio->bi_vcnt - 1], - page, len, offset, &same_page)) { + page, len, offset, same_page)) { bio->bi_iter.bi_size += len; return len; } @@ -1095,6 +1084,24 @@ int bio_add_page(struct bio *bio, struct page *page, __bio_add_page(bio, page, len, offset); return len; } + +/** + * bio_add_page - attempt to add page(s) to bio + * @bio: destination bio + * @page: start page to add + * @len: vec entry length, may cross pages + * @offset: vec entry offset relative to @page, may cross pages + * + * Attempt to add page(s) to the bio_vec maplist. Will only fail if the + * bio is full, or it is incorrectly used on a cloned bio. + */ +int bio_add_page(struct bio *bio, struct page *page, + unsigned int len, unsigned int offset) +{ + bool same_page = false; + + return bio_do_add_page(bio, page, len, offset, &same_page); +} EXPORT_SYMBOL(bio_add_page); void bio_add_folio_nofail(struct bio *bio, struct folio *folio, size_t len, @@ -1159,27 +1166,6 @@ void bio_iov_bvec_set(struct bio *bio, struct iov_iter *iter) bio_set_flag(bio, BIO_CLONED); } -static int bio_iov_add_folio(struct bio *bio, struct folio *folio, size_t len, - size_t offset) -{ - bool same_page = false; - - if (WARN_ON_ONCE(bio->bi_iter.bi_size > UINT_MAX - len)) - return -EIO; - - if (bio->bi_vcnt > 0 && - bvec_try_merge_page(&bio->bi_io_vec[bio->bi_vcnt - 1], - folio_page(folio, 0), len, offset, - &same_page)) { - bio->bi_iter.bi_size += len; - if (same_page && bio_flagged(bio, BIO_PAGE_PINNED)) - unpin_user_folio(folio, 1); - return 0; - } - bio_add_folio_nofail(bio, folio, len, offset); - return 0; -} - static unsigned int get_contig_folio_len(unsigned int *num_pages, struct page **pages, unsigned int i, struct folio *folio, size_t left, @@ -1274,6 +1260,7 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) for (left = size, i = 0; left > 0; left -= len, i += num_pages) { struct page *page = pages[i]; struct folio *folio = page_folio(page); + bool same_page = false; folio_offset = ((size_t)folio_page_idx(folio, page) << PAGE_SHIFT) + offset; @@ -1286,7 +1273,14 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) len = get_contig_folio_len(&num_pages, pages, i, folio, left, offset); - bio_iov_add_folio(bio, folio, len, folio_offset); + if (bio_do_add_page(bio, folio_page(folio, 0), len, + folio_offset, &same_page) != len) { + ret = -EINVAL; + break; + } + + if (same_page && bio_flagged(bio, BIO_PAGE_PINNED)) + unpin_user_folio(folio, 1); offset = 0; }
__bio_iov_iter_get_pages currently open codes adding pages to the bio, which duplicates a lot of code from bio_add_page. Add a lower level bio_do_add_page helpers that passes down the same_page output argument so that __bio_iov_iter_get_pages can reuse the code and also check for the error return from it - while no error should happen due to how the bvec space is used for the pin_user_space result I'd rather be safe than sorry and actually check for these impossible errors. Signed-off-by: Christoph Hellwig <hch@lst.de> --- block/bio.c | 66 ++++++++++++++++++++++++----------------------------- 1 file changed, 30 insertions(+), 36 deletions(-)