| Message ID | 20230315163549.295454-1-dhowells@redhat.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | splice, block: Use page pinning and kill ITER_PIPE | expand |
On Wed, Mar 15, 2023 at 9:35 AM David Howells <dhowells@redhat.com> wrote: > > ver #19) > - Remove a missed get_page() on the zeropage in shmem_splice_read(). Ack. I see nothing alarming in this series. Linus
On Wed, 15 Mar 2023 16:35:34 +0000, David Howells wrote: > The first half of this patchset 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[2]. Instead, we use filemap_splice_read(), which invokes > the buffered file reading code and splices from the pagecache into the > pipe; direct_splice_read(), which bulk-allocates a buffer, reads into it > and then pushes the filled pages into the pipe; or handle it in > filesystem-specific code. > > [...] Applied, thanks! [01/15] splice: Clean up direct_splice_read() a bit commit: d187b44bc9404581bad8d006d80937d1b3a2b0c0 [02/15] splice: Make do_splice_to() generic and export it commit: 6dc39c2949ee71ee9996d6190d374512ecf44982 [03/15] shmem: Implement splice-read commit: b81d7b89beccbeebe347c21c004665ffe07e36bb [04/15] overlayfs: Implement splice-read commit: f39de7bd1b5088241f0580b5fe5d76cc5569711f [05/15] coda: Implement splice-read commit: f0daac2d4dcd286168d7c70d0495328c096d4d96 [06/15] tty, proc, kernfs, random: Use direct_splice_read() commit: 82ab8404c910d4aba33f55257c2bbc8ea9cfad3c [07/15] splice: Do splice read from a file without using ITER_PIPE commit: 3eb3c59b128509a5e8a8349dafced64b9769438e [08/15] cifs: Use generic_file_splice_read() commit: fa9a848ded4984a8c64d0d20c3a5b0aab97c7754 [09/15] iov_iter: Kill ITER_PIPE commit: a53f5dee3448a51e6602a7f98952abaf19049641 [10/15] iomap: Don't get an reference on ZERO_PAGE for direct I/O block zeroing commit: 2102c4e41418fb5c2cdf26bf2b97922190e38ba2 [11/15] block: Fix bio_flagged() so that gcc can better optimise it commit: caf8aae59a7b1f668a32f91115ed8be3aebaaa41 [12/15] block: Replace BIO_NO_PAGE_REF with BIO_PAGE_REFFED with inverted logic commit: e812d15adde4363c95f1743b7dd4946f1a550c5c [13/15] block: Add BIO_PAGE_PINNED and associated infrastructure commit: b5596bf292996a5cd62f1fbc00c2c35f1a3faa12 [14/15] block: Convert bio_iov_iter_get_pages to use iov_iter_extract_pages commit: 648627d7077d4de810e5f4c09490cb993514a53f [15/15] block: convert bio_map_user_iov to use iov_iter_extract_pages commit: d187b44bc9404581bad8d006d80937d1b3a2b0c0 Best regards,
On Wed, Mar 15, 2023 at 11:47:14AM -0600, Jens Axboe wrote: > > [...] > > Applied, thanks! Dave, now that the basic patchset is in, can you resurrect the patch to conver the legacy direct-io code? That would allow us to instantly the PAGE_REF version of the bio_release_pages, and also be a giant step toward never modifying page contents from a regular get_user_pages, and thus fix the file system problems around that.
Hi Jens, Al, Christoph, The first half of this patchset 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[2]. Instead, we use filemap_splice_read(), which invokes the buffered file reading code and splices from the pagecache into the pipe; direct_splice_read(), which bulk-allocates a buffer, reads into it and then pushes the filled pages into the pipe; or handle it in filesystem-specific code. (1) Simplify the calculations for the number of pages to be reclaimed in direct_splice_read(). (2) Turn do_splice_to() into a helper so that it can be used by overlayfs and coda to perform the checks on the lower fs. (3) 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. (4) Provide overlayfs with its own splice_read to call down to a lower layer as overlayfs doesn't provide ->read_folio(). (5) Provide coda with its own splice_read to call down to a lower layer as coda doesn't provide ->read_folio(). (6) Direct ->splice_read to direct_splice_read() in tty, procfs, kernfs and random files as they just copy to the output buffer and don't splice pages. (7) Change generic_file_splice_read() to just switch between filemap_splice_read() and direct_splice_read() rather than using ITER_PIPE. (8) Make cifs use generic_file_splice_read(). (9) Remove ITER_PIPE and its paraphernalia as generic_file_splice_read() was the only user. The second half of the patchset rolls page-pinning out to the bio struct and the block layer, using iov_iter_extract_pages() to get pages and noting with BIO_PAGE_PINNED if the data pages attached to a bio are pinned. If the data pages come from a non-user-backed iterator, then the pages are left unpinned and unref'd, relying on whoever set up the I/O to do the retaining (10) Don't hold a ref on ZERO_PAGE in iomap_dio_zero(). (11) Fix bio_flagged() so that it doesn't prevent a gcc optimisation. (12) Make the bio struct carry a pair of flags to indicate the cleanup mode. BIO_NO_PAGE_REF is replaced with BIO_PAGE_REFFED (indicating FOLL_GET was used) and BIO_PAGE_PINNED (indicating FOLL_PIN was used) is added. BIO_PAGE_REFFED will go away, but at the moment fs/direct-io.c sets it and this series does not fully address that file. (13) Add a function, bio_release_page(), to release a page appropriately to the cleanup mode indicated by the BIO_PAGE_* flags. (14) Make bio_iov_iter_get_pages() use iov_iter_extract_pages() to retain the pages appropriately and clean them up later. (15) Make bio_map_user_iov() also use iov_iter_extract_pages(). I've pushed the patches here also: https://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs.git/log/?h=iov-extract David Changes: ======== ver #19) - Remove a missed get_page() on the zeropage in shmem_splice_read(). ver #18) - Split out the cifs bits from the patch the switches generic_file_splice_read() over to using the non-ITER_PIPE splicing. - Don't get/put refs on the zeropage in shmem_splice_read(). ver #17) - Rename do_splice_to() to vfs_splice_read() and export it so that it can be a helper and make overlayfs and coda use it, allowing duplicate checks to be removed. ver #16) - The filemap_get_pages() changes are now upstream. - filemap_splice_read() and direct_splice_read() are now upstream. - iov_iter_extract_pages() is now upstream. ver #15) - Fixed up some errors in overlayfs_splice_read(). ver #14) - Some changes to generic_file_buffered_splice_read(): - Rename to filemap_splice_read() and move to mm/filemap.c. - Create a helper, pipe_head_buf(). - Use init_sync_kiocb(). - Some changes to generic_file_direct_splice_read(): - Use alloc_pages_bulk_array() rather than alloc_pages_bulk_list(). - Use release_pages() instead of __free_page() in a loop. - Rename to direct_splice_read(). - Rearrange the patches to implement filemap_splice_read() and direct_splice_read() separately to changing generic_file_splice_read(). - Don't call generic_file_splice_read() when there isn't a ->read_folio(). - Insert patches to fix read_folio-less cases: - Make tty, procfs, kernfs and (u)random use direct_splice_read(). - Make overlayfs and coda call down to a lower layer. - Give shmem its own splice-read that doesn't insert missing pages. - Fixed a min() with mixed type args on some arches. ver #13) - Only use allocation in advance and ITER_BVEC for DIO read-splice. - Make buffered read-splice get pages directly from the pagecache. - Alter filemap_get_pages() & co. so that it doesn't need an iterator. ver #12) - Added the missing __bitwise on the iov_iter_extraction_t typedef. - Rebased on -rc7. - Don't specify FOLL_PIN to pin_user_pages_fast(). - Inserted patch at front to fix race between DIO read and truncation that caused memory corruption when iov_iter_revert() got called on an ITER_PIPE iterator[2]. - Inserted a patch after that to remove the now-unused ITER_PIPE and its helper functions. - Removed the ITER_PIPE bits from iov_iter_extract_pages(). ver #11) - Fix iov_iter_extract_kvec_pages() to include the offset into the page in the returned starting offset. - Use __bitwise for the extraction flags ver #10) - Fix use of i->kvec in iov_iter_extract_bvec_pages() to be i->bvec. - Drop bio_set_cleanup_mode(), open coding it instead. ver #9) - It's now not permitted to use FOLL_PIN outside of mm/, so: - Change iov_iter_extract_mode() into iov_iter_extract_will_pin() and return true/false instead of FOLL_PIN/0. - Drop of folio_put_unpin() and page_put_unpin() and instead call unpin_user_page() (and put_page()) directly as necessary. - Make __bio_release_pages() call bio_release_page() instead of unpin_user_page() as there's no BIO_* -> FOLL_* translation to do. - Drop the FOLL_* renumbering patch. - Change extract_flags to extraction_flags. ver #8) - Import Christoph Hellwig's changes. - Split the conversion-to-extraction patch. - Drop the extract_flags arg from iov_iter_extract_mode(). - Don't default bios to BIO_PAGE_REFFED, but set explicitly. - Switch FOLL_PIN and FOLL_GET when renumbering so PIN is at bit 0. - Switch BIO_PAGE_PINNED and BIO_PAGE_REFFED so PINNED is at bit 0. - We should always be using FOLL_PIN (not FOLL_GET) for DIO, so adjust the patches for that. ver #7) - For now, drop the parts to pass the I/O direction to iov_iter_*pages*() as it turned out to be a lot more complicated, with places not setting IOCB_WRITE when they should, for example. - Drop all the patches that changed things other then the block layer's bio handling. The netfslib and cifs changes can go into a separate patchset. - Add support for extracting pages from KVEC-type iterators. - When extracting from BVEC/KVEC, skip over empty vecs at the front. ver #6) - Fix write() syscall and co. not setting IOCB_WRITE. - Added iocb_is_read() and iocb_is_write() to check IOCB_WRITE. - Use op_is_write() in bio_copy_user_iov(). - Drop the iterator direction checks from smbd_recv(). - Define FOLL_SOURCE_BUF and FOLL_DEST_BUF and pass them in as part of gup_flags to iov_iter_get/extract_pages*(). - Replace iov_iter_get_pages*2() with iov_iter_get_pages*() and remove. - Add back the function to indicate the cleanup mode. - Drop the cleanup_mode return arg to iov_iter_extract_pages(). - Provide a helper to clean up a page. - Renumbered FOLL_GET and FOLL_PIN and made BIO_PAGE_REFFED/PINNED have the same numerical values, enforced with an assertion. - Converted AF_ALG, SCSI vhost, generic DIO, FUSE, splice to pipe, 9P and NFS. - Added in the patches to make CIFS do top-to-bottom iterators and use various of the added extraction functions. - Added a pair of work-in-progess patches to make sk_buff fragments store FOLL_GET and FOLL_PIN. ver #5) - Replace BIO_NO_PAGE_REF with BIO_PAGE_REFFED and split into own patch. - Transcribe FOLL_GET/PIN into BIO_PAGE_REFFED/PINNED flags. - Add patch to allow bio_flagged() to be combined by gcc. ver #4) - Drop the patch to move the FOLL_* flags to linux/mm_types.h as they're no longer referenced by linux/uio.h. - Add ITER_SOURCE/DEST cleanup patches. - Make iov_iter/netfslib iter extraction patches use ITER_SOURCE/DEST. - Allow additional gup_flags to be passed into iov_iter_extract_pages(). - Add struct bio patch. ver #3) - Switch to using EXPORT_SYMBOL_GPL to prevent indirect 3rd-party access to get/pin_user_pages_fast()[1]. ver #2) - Rolled the extraction cleanup mode query function into the extraction function, returning the indication through the argument list. - Fixed patch 4 (extract to scatterlist) to actually use the new extraction API. Link: https://lore.kernel.org/r/Y3zFzdWnWlEJ8X8/@infradead.org/ [1] Link: https://lore.kernel.org/r/000000000000b0b3c005f3a09383@google.com/ [2] Link: https://lore.kernel.org/r/166697254399.61150.1256557652599252121.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/166722777223.2555743.162508599131141451.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/166732024173.3186319.18204305072070871546.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/166869687556.3723671.10061142538708346995.stgit@warthog.procyon.org.uk/ # rfc Link: https://lore.kernel.org/r/166920902005.1461876.2786264600108839814.stgit@warthog.procyon.org.uk/ # v2 Link: https://lore.kernel.org/r/166997419665.9475.15014699817597102032.stgit@warthog.procyon.org.uk/ # v3 Link: https://lore.kernel.org/r/167305160937.1521586.133299343565358971.stgit@warthog.procyon.org.uk/ # v4 Link: https://lore.kernel.org/r/167344725490.2425628.13771289553670112965.stgit@warthog.procyon.org.uk/ # v5 Link: https://lore.kernel.org/r/167391047703.2311931.8115712773222260073.stgit@warthog.procyon.org.uk/ # v6 Link: https://lore.kernel.org/r/20230120175556.3556978-1-dhowells@redhat.com/ # v7 Link: https://lore.kernel.org/r/20230123173007.325544-1-dhowells@redhat.com/ # v8 Link: https://lore.kernel.org/r/20230124170108.1070389-1-dhowells@redhat.com/ # v9 Link: https://lore.kernel.org/r/20230125210657.2335748-1-dhowells@redhat.com/ # v10 Link: https://lore.kernel.org/r/20230126141626.2809643-1-dhowells@redhat.com/ # v11 Link: https://lore.kernel.org/r/20230207171305.3716974-1-dhowells@redhat.com/ # v12 Link: https://lore.kernel.org/r/20230209102954.528942-1-dhowells@redhat.com/ # v13 Link: https://lore.kernel.org/r/20230214171330.2722188-1-dhowells@redhat.com/ # v14 Link: https://lore.kernel.org/r/20230308143754.1976726-1-dhowells@redhat.com/ # v16 Link: https://lore.kernel.org/r/20230308165251.2078898-1-dhowells@redhat.com/ # v17 Link: https://lore.kernel.org/r/20230314220757.3827941-1-dhowells@redhat.com/ # v18 Additional patches that got folded in: Link: https://lore.kernel.org/r/20230213134619.2198965-1-dhowells@redhat.com/ # v1 Link: https://lore.kernel.org/r/20230213153301.2338806-1-dhowells@redhat.com/ # v2 Link: https://lore.kernel.org/r/20230214083710.2547248-1-dhowells@redhat.com/ # v3 Christoph Hellwig (1): block: Replace BIO_NO_PAGE_REF with BIO_PAGE_REFFED with inverted logic David Howells (14): splice: Clean up direct_splice_read() a bit splice: Make do_splice_to() generic and export it shmem: Implement splice-read overlayfs: Implement splice-read coda: Implement splice-read tty, proc, kernfs, random: Use direct_splice_read() splice: Do splice read from a file without using ITER_PIPE cifs: Use generic_file_splice_read() iov_iter: Kill ITER_PIPE iomap: Don't get an reference on ZERO_PAGE for direct I/O block zeroing block: Fix bio_flagged() so that gcc can better optimise it block: Add BIO_PAGE_PINNED and associated infrastructure block: Convert bio_iov_iter_get_pages to use iov_iter_extract_pages block: convert bio_map_user_iov to use iov_iter_extract_pages block/bio.c | 29 +-- block/blk-map.c | 22 +- block/blk.h | 12 ++ drivers/char/random.c | 4 +- drivers/tty/tty_io.c | 4 +- fs/cifs/cifsfs.c | 8 +- fs/cifs/cifsfs.h | 3 - fs/cifs/file.c | 16 -- fs/coda/file.c | 29 ++- fs/direct-io.c | 2 + fs/iomap/direct-io.c | 1 - fs/kernfs/file.c | 2 +- fs/overlayfs/file.c | 23 +- fs/proc/inode.c | 4 +- fs/proc/proc_sysctl.c | 2 +- fs/proc_namespace.c | 6 +- fs/splice.c | 76 +++---- include/linux/bio.h | 5 +- include/linux/blk_types.h | 3 +- include/linux/splice.h | 3 + include/linux/uio.h | 14 -- lib/iov_iter.c | 429 +------------------------------------- mm/filemap.c | 4 +- mm/shmem.c | 134 +++++++++++- 24 files changed, 284 insertions(+), 551 deletions(-)