fs: consolidate fsverity_info lookup in buffer.c

Look up the fsverity_info once in end_buffer_async_read_io, and then
pass it along to the I/O completion workqueue in
struct postprocess_bh_ctx.

This amortizes the lookup better once it becomes less efficient.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20260202060754.270269-8-hch@lst.de
Signed-off-by: Eric Biggers <ebiggers@kernel.org>

1 files changed, 11 insertions, 16 deletions

diff --git a/fs/buffer.c b/fs/buffer.c
index 3982253b6805..f4b3297ef1b1 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -302,6 +302,7 @@ still_busy:
 struct postprocess_bh_ctx {
 	struct work_struct work;
 	struct buffer_head *bh;
+	struct fsverity_info *vi;
 };
 
 static void verify_bh(struct work_struct *work)
@@ -309,25 +310,14 @@ static void verify_bh(struct work_struct *work)
 	struct postprocess_bh_ctx *ctx =
 		container_of(work, struct postprocess_bh_ctx, work);
 	struct buffer_head *bh = ctx->bh;
-	struct inode *inode = bh->b_folio->mapping->host;
 	bool valid;
 
-	valid = fsverity_verify_blocks(*fsverity_info_addr(inode), bh->b_folio,
-				       bh->b_size, bh_offset(bh));
+	valid = fsverity_verify_blocks(ctx->vi, bh->b_folio, bh->b_size,
+				       bh_offset(bh));
 	end_buffer_async_read(bh, valid);
 	kfree(ctx);
 }
 
-static bool need_fsverity(struct buffer_head *bh)
-{
-	struct folio *folio = bh->b_folio;
-	struct inode *inode = folio->mapping->host;
-
-	return fsverity_active(inode) &&
-		/* needed by ext4 */
-		folio->index < DIV_ROUND_UP(inode->i_size, PAGE_SIZE);
-}
-
 static void decrypt_bh(struct work_struct *work)
 {
 	struct postprocess_bh_ctx *ctx =
@@ -337,7 +327,7 @@ static void decrypt_bh(struct work_struct *work)
 
 	err = fscrypt_decrypt_pagecache_blocks(bh->b_folio, bh->b_size,
 					       bh_offset(bh));
-	if (err == 0 && need_fsverity(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
@@ -359,15 +349,20 @@ static void end_buffer_async_read_io(struct buffer_head *bh, int uptodate)
 {
 	struct inode *inode = bh->b_folio->mapping->host;
 	bool decrypt = fscrypt_inode_uses_fs_layer_crypto(inode);
-	bool verify = need_fsverity(bh);
+	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 || verify)) {
+	if (uptodate && (decrypt || vi)) {
 		struct postprocess_bh_ctx *ctx =
 			kmalloc(sizeof(*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);