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Subject[PATCH v2 4/6] fscrypt: Cleanup page locking requirements for fscrypt_{decrypt,encrypt}_page()
Date
Rename the FS_CFLG_INPLACE_ENCRYPTION flag to FS_CFLG_OWN_PAGES which,
when set, indicates that the fs uses pages under its own control as
opposed to writeback pages which require locking and a bounce buffer for
encryption.

Signed-off-by: David Gstir <david@sigma-star.at>
---
fs/crypto/crypto.c | 11 ++++++++---
fs/ext4/inode.c | 1 -
fs/f2fs/data.c | 1 -
include/linux/fscrypto.h | 2 +-
4 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 8805ec5d7de2..6f5c3a8df70b 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -238,7 +238,7 @@ static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags)
* fscrypt_restore_control_page() on the returned ciphertext page to
* release the bounce buffer and the encryption context.
*
- * In-place encryption is used by setting the FS_CFLG_INPLACE_ENCRYPTION flag in
+ * In-place encryption is used by setting the FS_CFLG_OWN_PAGES flag in
* fscrypt_operations. Here, the input-page is returned with its content
* encrypted.
*
@@ -258,7 +258,7 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,

BUG_ON(len % FS_CRYPTO_BLOCK_SIZE != 0);

- if (inode->i_sb->s_cop->flags & FS_CFLG_INPLACE_ENCRYPTION) {
+ if (inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES) {
/* with inplace-encryption we just encrypt the page */
err = do_page_crypto(inode, FS_ENCRYPT, lblk_num,
page, ciphertext_page,
@@ -269,6 +269,8 @@ struct page *fscrypt_encrypt_page(const struct inode *inode,
return ciphertext_page;
}

+ BUG_ON(!PageLocked(page));
+
ctx = fscrypt_get_ctx(inode, gfp_flags);
if (IS_ERR(ctx))
return (struct page *)ctx;
@@ -301,7 +303,7 @@ EXPORT_SYMBOL(fscrypt_encrypt_page);
* fscrypt_decrypt_page() - Decrypts a page in-place
* @inode: The corresponding inode for the page to decrypt.
* @page: The page to decrypt. Must be locked in case
- * it is a writeback page.
+ * it is a writeback page (FS_CFLG_OWN_PAGES unset).
* @len: Number of bytes in @page to be decrypted.
* @offs: Start of data in @page.
* @lblk_num: Logical block number.
@@ -315,6 +317,9 @@ EXPORT_SYMBOL(fscrypt_encrypt_page);
int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
unsigned int len, unsigned int offs, u64 lblk_num)
{
+ if (!(inode->i_sb->s_cop->flags & FS_CFLG_OWN_PAGES))
+ BUG_ON(!PageLocked(page));
+
return do_page_crypto(inode, FS_DECRYPT, lblk_num, page, page, len,
offs, GFP_NOFS);
}
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 1485ac273bfb..fb2b514f675b 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3744,7 +3744,6 @@ static int __ext4_block_zero_page_range(handle_t *handle,
/* We expect the key to be set. */
BUG_ON(!fscrypt_has_encryption_key(inode));
BUG_ON(blocksize != PAGE_SIZE);
- BUG_ON(!PageLocked(page));
WARN_ON_ONCE(fscrypt_decrypt_page(page->mapping->host,
page, PAGE_SIZE, 0, page->index));
}
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 435590c4b341..9f0ba90b92e4 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1194,7 +1194,6 @@ int do_write_data_page(struct f2fs_io_info *fio)
f2fs_wait_on_encrypted_page_writeback(F2FS_I_SB(inode),
fio->old_blkaddr);
retry_encrypt:
- BUG_ON(!PageLocked(fio->page));
fio->encrypted_page = fscrypt_encrypt_page(inode, fio->page,
PAGE_SIZE, 0,
fio->page->index,
diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h
index e9648b62eca6..65be74f3afb6 100644
--- a/include/linux/fscrypto.h
+++ b/include/linux/fscrypto.h
@@ -156,7 +156,7 @@ struct fscrypt_name {
/*
* fscrypt superblock flags
*/
-#define FS_CFLG_INPLACE_ENCRYPTION (1U << 1)
+#define FS_CFLG_OWN_PAGES (1U << 1)

/*
* crypto opertions for filesystems
--
2.10.1
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