[PATCH 10/16] fs/buffer: Remove fs-layer decryption code

[Eric Biggers <ebiggers@kernel.org>]

Now that fscrypt's file contents en/decryption is always implemented
using blk-crypto when the filesystem is block-based, the fs-layer
decryption code in fs/buffer.c is unused code.  Remove it.

Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
 fs/buffer.c | 45 ++++++++-------------------------------------
 1 file changed, 8 insertions(+), 37 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 9af5f061a1f8..21dd9596a941 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -334,82 +334,53 @@ static void end_buffer_async_read(struct buffer_head *bh, int uptodate)
 
 still_busy:
 	spin_unlock_irqrestore(&first->b_uptodate_lock, flags);
 }
 
-struct postprocess_bh_ctx {
+struct verify_bh_ctx {
 	struct work_struct work;
 	struct buffer_head *bh;
 	struct fsverity_info *vi;
 };
 
 static void verify_bh(struct work_struct *work)
 {
-	struct postprocess_bh_ctx *ctx =
-		container_of(work, struct postprocess_bh_ctx, work);
+	struct verify_bh_ctx *ctx =
+		container_of(work, struct verify_bh_ctx, work);
 	struct buffer_head *bh = ctx->bh;
 	bool valid;
 
 	valid = fsverity_verify_blocks(ctx->vi, bh->b_folio, bh->b_size,
 				       bh_offset(bh));
 	end_buffer_async_read(bh, valid);
 	kfree(ctx);
 }
 
-static void decrypt_bh(struct work_struct *work)
-{
-	struct postprocess_bh_ctx *ctx =
-		container_of(work, struct postprocess_bh_ctx, work);
-	struct buffer_head *bh = ctx->bh;
-	int err;
-
-	err = fscrypt_decrypt_pagecache_blocks(bh->b_folio, bh->b_size,
-					       bh_offset(bh));
-	if (err == 0 && ctx->vi) {
-		/*
-		 * We use different work queues for decryption and for verity
-		 * because verity may require reading metadata pages that need
-		 * decryption, and we shouldn't recurse to the same workqueue.
-		 */
-		INIT_WORK(&ctx->work, verify_bh);
-		fsverity_enqueue_verify_work(&ctx->work);
-		return;
-	}
-	end_buffer_async_read(bh, err == 0);
-	kfree(ctx);
-}
-
 /*
  * I/O completion handler for block_read_full_folio() - folios
  * which come unlocked at the end of I/O.
  */
 static void bh_end_async_read(struct bio *bio)
 {
 	struct buffer_head *bh;
 	bool uptodate = bio_endio_bh(bio, &bh);
 	struct inode *inode = bh->b_folio->mapping->host;
-	bool decrypt = fscrypt_inode_uses_fs_layer_crypto(inode);
 	struct fsverity_info *vi = NULL;
 
 	/* needed by ext4 */
 	if (bh->b_folio->index < DIV_ROUND_UP(inode->i_size, PAGE_SIZE))
 		vi = fsverity_get_info(inode);
 
-	/* Decrypt (with fscrypt) and/or verify (with fsverity) if needed. */
-	if (uptodate && (decrypt || vi)) {
-		struct postprocess_bh_ctx *ctx = kmalloc_obj(*ctx, GFP_ATOMIC);
+	/* Verify (with fsverity) if needed. */
+	if (vi && uptodate) {
+		struct verify_bh_ctx *ctx = kmalloc_obj(*ctx, GFP_ATOMIC);
 
 		if (ctx) {
 			ctx->bh = bh;
 			ctx->vi = vi;
-			if (decrypt) {
-				INIT_WORK(&ctx->work, decrypt_bh);
-				fscrypt_enqueue_decrypt_work(&ctx->work);
-			} else {
-				INIT_WORK(&ctx->work, verify_bh);
-				fsverity_enqueue_verify_work(&ctx->work);
-			}
+			INIT_WORK(&ctx->work, verify_bh);
+			fsverity_enqueue_verify_work(&ctx->work);
 			return;
 		}
 		uptodate = false;
 	}
 	end_buffer_async_read(bh, uptodate);
-- 
2.54.0