| Message ID | 20200717014540.71515-4-satyat@google.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | add support for direct I/O with fscrypt using blk-crypto | expand |
On Fri, Jul 17, 2020 at 01:45:36AM +0000, Satya Tangirala wrote: > From: Eric Biggers <ebiggers@google.com> > > Wire up iomap direct I/O with the fscrypt additions for direct I/O, > and set bio crypt contexts on bios when appropriate. > > Make iomap_dio_bio_actor() call fscrypt_limit_io_pages() to ensure that > DUNs remain contiguous within a bio, since it works directly with logical > ranges and can't call fscrypt_mergeable_bio() on each page. This commit message is still confusing. How about the following: "Wire up iomap direct I/O with the fscrypt additions for direct I/O. This allows ext4 to support direct I/O on encrypted files when inline encryption is enabled. This change consists of two parts: - Set a bio_crypt_ctx on bios for encrypted files, so that the file contents get encrypted (or decrypted). - Ensure that encryption data unit numbers (DUNs) are contiguous within each bio. Use the new function fscrypt_limit_io_pages() for this, since the iomap code works directly with logical ranges and thus doesn't have a chance to call fscrypt_mergeable_bio() on each page. Note that fscrypt_limit_io_pages() is normally a no-op, as normally the DUNs simply increment along with the logical blocks. But it's needed to handle an edge case in one of the fscrypt IV generation methods." > @@ -183,11 +184,14 @@ static void > iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos, > unsigned len) > { > + struct inode *inode = file_inode(dio->iocb->ki_filp); > struct page *page = ZERO_PAGE(0); > int flags = REQ_SYNC | REQ_IDLE; > struct bio *bio; > > bio = bio_alloc(GFP_KERNEL, 1); > + fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits, > + GFP_KERNEL); > bio_set_dev(bio, iomap->bdev); > bio->bi_iter.bi_sector = iomap_sector(iomap, pos); > bio->bi_private = dio; iomap_dio_zero() is only used on partial filesystem blocks. But, we only allow direct I/O on encrypted files when the I/O is filesystem-block-aligned. So this part appears to be unnecessary. How about replacing it with: /* encrypted direct I/O is guaranteed to be fs-block aligned */ WARN_ON_ONCE(fscrypt_needs_contents_encryption(inode)); > @@ -253,6 +257,7 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, > ret = nr_pages; > goto out; > } > + nr_pages = fscrypt_limit_io_pages(inode, pos, nr_pages); > > if (need_zeroout) { > /* zero out from the start of the block to the write offset */ > @@ -270,6 +275,8 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, > } > > bio = bio_alloc(GFP_KERNEL, nr_pages); > + fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits, > + GFP_KERNEL); > bio_set_dev(bio, iomap->bdev); > bio->bi_iter.bi_sector = iomap_sector(iomap, pos); > bio->bi_write_hint = dio->iocb->ki_hint; > @@ -307,6 +314,7 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, > copied += n; > > nr_pages = iov_iter_npages(dio->submit.iter, BIO_MAX_PAGES); > + nr_pages = fscrypt_limit_io_pages(inode, pos, nr_pages); > iomap_dio_submit_bio(dio, iomap, bio, pos); > pos += n; > } while (nr_pages); I think the part at the end is wrong. We want to limit the *next* bio, not the current one. So 'pos' needs to be updated first. I think it should be: iomap_dio_submit_bio(dio, iomap, bio, pos); pos += n; nr_pages = iov_iter_npages(dio->submit.iter, BIO_MAX_PAGES); nr_pages = fscrypt_limit_io_pages(inode, pos, nr_pages);
diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c index ec7b78e6feca..4507dc16dbe5 100644 --- a/fs/iomap/direct-io.c +++ b/fs/iomap/direct-io.c @@ -6,6 +6,7 @@ #include <linux/module.h> #include <linux/compiler.h> #include <linux/fs.h> +#include <linux/fscrypt.h> #include <linux/iomap.h> #include <linux/backing-dev.h> #include <linux/uio.h> @@ -183,11 +184,14 @@ static void iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos, unsigned len) { + struct inode *inode = file_inode(dio->iocb->ki_filp); struct page *page = ZERO_PAGE(0); int flags = REQ_SYNC | REQ_IDLE; struct bio *bio; bio = bio_alloc(GFP_KERNEL, 1); + fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits, + GFP_KERNEL); bio_set_dev(bio, iomap->bdev); bio->bi_iter.bi_sector = iomap_sector(iomap, pos); bio->bi_private = dio; @@ -253,6 +257,7 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, ret = nr_pages; goto out; } + nr_pages = fscrypt_limit_io_pages(inode, pos, nr_pages); if (need_zeroout) { /* zero out from the start of the block to the write offset */ @@ -270,6 +275,8 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, } bio = bio_alloc(GFP_KERNEL, nr_pages); + fscrypt_set_bio_crypt_ctx(bio, inode, pos >> inode->i_blkbits, + GFP_KERNEL); bio_set_dev(bio, iomap->bdev); bio->bi_iter.bi_sector = iomap_sector(iomap, pos); bio->bi_write_hint = dio->iocb->ki_hint; @@ -307,6 +314,7 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length, copied += n; nr_pages = iov_iter_npages(dio->submit.iter, BIO_MAX_PAGES); + nr_pages = fscrypt_limit_io_pages(inode, pos, nr_pages); iomap_dio_submit_bio(dio, iomap, bio, pos); pos += n; } while (nr_pages);