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-rw-r--r--fs/crypto/crypto.c46
1 files changed, 32 insertions, 14 deletions
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index f82c45ac285a..45c3d0427fb2 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -283,29 +283,47 @@ int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page,
EXPORT_SYMBOL(fscrypt_encrypt_block_inplace);
/**
- * 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.
- * @len: Number of bytes in @page to be decrypted.
- * @offs: Start of data in @page.
- * @lblk_num: Logical block number.
+ * fscrypt_decrypt_pagecache_blocks() - Decrypt filesystem blocks in a pagecache page
+ * @page: The locked pagecache page containing the block(s) to decrypt
+ * @len: Total size of the block(s) to decrypt. Must be a nonzero
+ * multiple of the filesystem's block size.
+ * @offs: Byte offset within @page of the first block to decrypt. Must be
+ * a multiple of the filesystem's block size.
*
- * Decrypts page in-place using the ctx encryption context.
+ * The specified block(s) are decrypted in-place within the pagecache page,
+ * which must still be locked and not uptodate. Normally, blocksize ==
+ * PAGE_SIZE and the whole page is decrypted at once.
*
- * Called from the read completion callback.
+ * This is for use by the filesystem's ->readpages() method.
*
- * Return: Zero on success, non-zero otherwise.
+ * Return: 0 on success; -errno on failure
*/
-int fscrypt_decrypt_page(const struct inode *inode, struct page *page,
- unsigned int len, unsigned int offs, u64 lblk_num)
+int fscrypt_decrypt_pagecache_blocks(struct page *page, unsigned int len,
+ unsigned int offs)
{
+ const struct inode *inode = page->mapping->host;
+ const unsigned int blockbits = inode->i_blkbits;
+ const unsigned int blocksize = 1 << blockbits;
+ u64 lblk_num = ((u64)page->index << (PAGE_SHIFT - blockbits)) +
+ (offs >> blockbits);
+ unsigned int i;
+ int err;
+
if (WARN_ON_ONCE(!PageLocked(page)))
return -EINVAL;
- return fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page, page,
- len, offs, GFP_NOFS);
+ if (WARN_ON_ONCE(len <= 0 || !IS_ALIGNED(len | offs, blocksize)))
+ return -EINVAL;
+
+ for (i = offs; i < offs + len; i += blocksize, lblk_num++) {
+ err = fscrypt_crypt_block(inode, FS_DECRYPT, lblk_num, page,
+ page, blocksize, i, GFP_NOFS);
+ if (err)
+ return err;
+ }
+ return 0;
}
-EXPORT_SYMBOL(fscrypt_decrypt_page);
+EXPORT_SYMBOL(fscrypt_decrypt_pagecache_blocks);
/**
* fscrypt_decrypt_block_inplace() - Decrypt a filesystem block in-place