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Date: Fri, 12 Jan 2018 19:41:28 +0530
From: Chandan Rajendra <chandan@...ux.vnet.ibm.com>
To: linux-ext4@...r.kernel.org
Cc: Chandan Rajendra <chandan@...ux.vnet.ibm.com>,
linux-fsdevel@...r.kernel.org, tytso@....edu
Subject: [RFC PATCH 7/8] ext4: decrypt blocks whose size is less than page size
This commit adds code to decrypt all file blocks mapped by page.
Signed-off-by: Chandan Rajendra <chandan@...ux.vnet.ibm.com>
---
fs/crypto/bio.c | 6 +-
fs/ext4/readpage.c | 267 +++++++++++++++++++++++++++++++++++++++-
include/linux/fscrypt.h | 1 +
include/linux/fscrypt_notsupp.h | 4 +-
include/linux/fscrypt_supp.h | 3 +-
5 files changed, 274 insertions(+), 7 deletions(-)
diff --git a/fs/crypto/bio.c b/fs/crypto/bio.c
index eb6e06a..2744e55 100644
--- a/fs/crypto/bio.c
+++ b/fs/crypto/bio.c
@@ -70,9 +70,11 @@ static void completion_pages(struct work_struct *work)
bio_put(bio);
}
-void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio)
+void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio,
+ void (*process_bio)(struct work_struct *))
{
- INIT_WORK(&ctx->r.work, completion_pages);
+ INIT_WORK(&ctx->r.work,
+ process_bio ? process_bio : completion_pages);
ctx->r.bio = bio;
queue_work(fscrypt_read_workqueue, &ctx->r.work);
}
diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c
index 0be590b..e494e2d 100644
--- a/fs/ext4/readpage.c
+++ b/fs/ext4/readpage.c
@@ -62,6 +62,143 @@ static inline bool ext4_bio_encrypted(struct bio *bio)
#endif
}
+static void ext4_complete_block(struct work_struct *work)
+{
+ struct fscrypt_ctx *ctx =
+ container_of(work, struct fscrypt_ctx, r.work);
+ struct buffer_head *first, *bh, *tmp;
+ struct bio *bio;
+ struct bio_vec *bv;
+ struct page *page;
+ struct inode *inode;
+ u64 blk_nr;
+ unsigned long flags;
+ int page_uptodate = 1;
+ int ret;
+
+ bio = ctx->r.bio;
+ BUG_ON(bio->bi_vcnt != 1);
+
+ bv = bio->bi_io_vec;
+ page = bv->bv_page;
+ inode = page->mapping->host;
+
+ BUG_ON(bv->bv_len != i_blocksize(inode));
+
+ blk_nr = page->index << (PAGE_SHIFT - inode->i_blkbits);
+ blk_nr += bv->bv_offset >> inode->i_blkbits;
+
+ bh = ctx->r.bh;
+
+ ret = fscrypt_decrypt_page(inode, page, bv->bv_len,
+ bv->bv_offset, blk_nr);
+ if (ret) {
+ WARN_ON_ONCE(1);
+ SetPageError(page);
+ } else {
+ set_buffer_uptodate(bh);
+ }
+
+ fscrypt_release_ctx(ctx);
+ bio_put(bio);
+
+ first = page_buffers(page);
+ local_irq_save(flags);
+ bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
+
+ clear_buffer_async_read(bh);
+ unlock_buffer(bh);
+ tmp = bh;
+ do {
+ if (!buffer_uptodate(tmp))
+ page_uptodate = 0;
+ if (buffer_async_read(tmp)) {
+ BUG_ON(!buffer_locked(tmp));
+ goto still_busy;
+ }
+ tmp = tmp->b_this_page;
+ } while (tmp != bh);
+
+ bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+ local_irq_restore(flags);
+
+ if (page_uptodate && !PageError(page))
+ SetPageUptodate(page);
+ unlock_page(page);
+ return;
+
+still_busy:
+ bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+ local_irq_restore(flags);
+ return;
+}
+
+static void block_end_io(struct bio *bio)
+{
+ struct buffer_head *bh;
+ struct buffer_head *first;
+ struct buffer_head *tmp;
+ unsigned long flags;
+ struct page *page;
+ int page_uptodate = 1;
+
+ if (ext4_bio_encrypted(bio)) {
+ struct fscrypt_ctx *ctx = bio->bi_private;
+ bh = ctx->r.bh;
+ if (bio->bi_status) {
+ fscrypt_release_ctx(ctx);
+ } else {
+ fscrypt_decrypt_bio_pages(ctx, bio,
+ ext4_complete_block);
+ return;
+ }
+ } else {
+ bh = bio->bi_private;
+ }
+
+ page = bh->b_page;
+
+ if (!bio->bi_status) {
+ set_buffer_uptodate(bh);
+ } else {
+ clear_buffer_uptodate(bh);
+ /* chandan: buffer_io_error(bh); */
+ SetPageError(page);
+ }
+
+ first = page_buffers(page);
+ local_irq_save(flags);
+ bit_spin_lock(BH_Uptodate_Lock, &first->b_state);
+ clear_buffer_async_read(bh);
+ unlock_buffer(bh);
+ tmp = bh;
+ do {
+ if (!buffer_uptodate(tmp))
+ page_uptodate = 0;
+ if (buffer_async_read(tmp)) {
+ BUG_ON(!buffer_locked(tmp));
+ goto still_busy;
+ }
+ tmp = tmp->b_this_page;
+ } while (tmp != bh);
+ bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+ local_irq_restore(flags);
+
+ /*
+ * If none of the buffers had errors and they are all
+ * uptodate then we can set the page uptodate.
+ */
+ if (page_uptodate && !PageError(page))
+ SetPageUptodate(page);
+ unlock_page(page);
+ return;
+
+still_busy:
+ bit_spin_unlock(BH_Uptodate_Lock, &first->b_state);
+ local_irq_restore(flags);
+ return;
+}
+
/*
* I/O completion handler for multipage BIOs.
*
@@ -83,7 +220,7 @@ static void mpage_end_io(struct bio *bio)
if (bio->bi_status) {
fscrypt_release_ctx(bio->bi_private);
} else {
- fscrypt_decrypt_bio_pages(bio->bi_private, bio);
+ fscrypt_decrypt_bio_pages(bio->bi_private, bio, NULL);
return;
}
}
@@ -102,6 +239,132 @@ static void mpage_end_io(struct bio *bio)
bio_put(bio);
}
+int ext4_block_read_full_page(struct page *page)
+{
+ struct inode *inode = page->mapping->host;
+ struct fscrypt_ctx *ctx;
+ struct bio *bio;
+ sector_t iblock, lblock;
+ struct buffer_head *bh, *head, *arr[MAX_BUF_PER_PAGE];
+ unsigned int blocksize, bbits;
+ int nr, i;
+ int fully_mapped = 1;
+ int ret;
+
+ head = create_page_buffers(page, inode, 0);
+ blocksize = head->b_size;
+ bbits = block_size_bits(blocksize);
+
+ iblock = (sector_t)page->index << (PAGE_SHIFT - bbits);
+ lblock = (i_size_read(inode)+blocksize-1) >> bbits;
+ bh = head;
+ nr = 0;
+ i = 0;
+
+ do {
+ if (buffer_uptodate(bh))
+ continue;
+
+ if (!buffer_mapped(bh)) {
+ int err = 0;
+
+ fully_mapped = 0;
+ if (iblock < lblock) {
+ WARN_ON(bh->b_size != blocksize);
+ err = ext4_get_block(inode, iblock, bh, 0);
+ if (err)
+ SetPageError(page);
+ }
+ if (!buffer_mapped(bh)) {
+ zero_user(page, i << bbits, blocksize);
+ if (!err)
+ set_buffer_uptodate(bh);
+ continue;
+ }
+ /*
+ * get_block() might have updated the buffer
+ * synchronously
+ */
+ if (buffer_uptodate(bh))
+ continue;
+ }
+ arr[nr++] = bh;
+ } while (i++, iblock++, (bh = bh->b_this_page) != head);
+
+ if (fully_mapped)
+ SetPageMappedToDisk(page);
+
+ if (!nr) {
+ /*
+ * All buffers are uptodate - we can set the page uptodate
+ * as well. But not if ext4_get_block() returned an error.
+ */
+ if (!PageError(page))
+ SetPageUptodate(page);
+ unlock_page(page);
+ return 0;
+ }
+
+ /* Stage two: lock the buffers */
+ for (i = 0; i < nr; i++) {
+ bh = arr[i];
+ lock_buffer(bh);
+ set_buffer_async_read(bh);
+ }
+
+ /*
+ * Stage 3: start the IO. Check for uptodateness
+ * inside the buffer lock in case another process reading
+ * the underlying blockdev brought it uptodate (the sct fix).
+ */
+ for (i = 0; i < nr; i++) {
+ ctx = NULL;
+ bh = arr[i];
+
+ if (buffer_uptodate(bh)) {
+ end_buffer_async_read(bh, 1);
+ continue;
+ }
+
+ if (ext4_encrypted_inode(inode)
+ && S_ISREG(inode->i_mode)) {
+ ctx = fscrypt_get_ctx(inode, GFP_NOFS);
+ if (IS_ERR(ctx)) {
+ set_page_error:
+ SetPageError(page);
+ zero_user_segment(page, bh_offset(bh), blocksize);
+ continue;
+ }
+ ctx->r.bh = bh;
+ }
+
+ bio = bio_alloc(GFP_KERNEL, 1);
+ if (!bio) {
+ if (ctx)
+ fscrypt_release_ctx(ctx);
+ goto set_page_error;
+ }
+
+ bio->bi_iter.bi_sector = bh->b_blocknr * (blocksize >> 9);
+ bio_set_dev(bio, bh->b_bdev);
+ bio->bi_write_hint = 0;
+
+ ret = bio_add_page(bio, bh->b_page, blocksize, bh_offset(bh));
+ BUG_ON(bio->bi_iter.bi_size != blocksize);
+
+ bio->bi_end_io = block_end_io;
+ if (ctx)
+ bio->bi_private = ctx;
+ else
+ bio->bi_private = bh;
+ bio_set_op_attrs(bio, REQ_OP_READ, 0);
+
+ submit_bio(bio);
+ }
+
+ return 0;
+}
+
int ext4_mpage_readpages(struct address_space *mapping,
struct list_head *pages, struct page *page,
unsigned nr_pages)
@@ -286,7 +549,7 @@ int ext4_mpage_readpages(struct address_space *mapping,
bio = NULL;
}
if (!PageUptodate(page))
- block_read_full_page(page, ext4_get_block);
+ ext4_block_read_full_page(page);
else
unlock_page(page);
next_page:
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 08b4b40..98c51eb 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -34,6 +34,7 @@ struct fscrypt_ctx {
} w;
struct {
struct bio *bio;
+ struct buffer_head *bh;
struct work_struct work;
} r;
struct list_head free_list; /* Free list */
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
index 019ddce..7da0692 100644
--- a/include/linux/fscrypt_notsupp.h
+++ b/include/linux/fscrypt_notsupp.h
@@ -164,8 +164,8 @@ static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
}
/* bio.c */
-static inline void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx,
- struct bio *bio)
+static inline void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio,
+ void (* process_bio)(struct work_struct *))
{
return;
}
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
index 983d06f..1d4e8ae 100644
--- a/include/linux/fscrypt_supp.h
+++ b/include/linux/fscrypt_supp.h
@@ -144,7 +144,8 @@ static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
}
/* bio.c */
-extern void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *);
+extern void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *ctx, struct bio *bio,
+ void (* process_bio)(struct work_struct *));
extern void fscrypt_pullback_bio_page(struct page **, bool);
extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t,
unsigned int);
--
2.9.5
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