diff --git a/fs/ext4/readpage.c b/fs/ext4/readpage.c index fef7755300c3..410c904cf59b 100644 --- a/fs/ext4/readpage.c +++ b/fs/ext4/readpage.c @@ -57,6 +57,7 @@ enum bio_post_read_step { STEP_INITIAL = 0, STEP_DECRYPT, STEP_VERITY, + STEP_MAX, }; struct bio_post_read_ctx { @@ -106,10 +107,22 @@ static void verity_work(struct work_struct *work) { struct bio_post_read_ctx *ctx = container_of(work, struct bio_post_read_ctx, work); + struct bio *bio = ctx->bio; - fsverity_verify_bio(ctx->bio); + /* + * fsverity_verify_bio() may call readpages() again, and although verity + * will be disabled for that, decryption may still be needed, causing + * another bio_post_read_ctx to be allocated. So to guarantee that + * mempool_alloc() never deadlocks we must free the current ctx first. + * This is safe because verity is the last post-read step. + */ + BUILD_BUG_ON(STEP_VERITY + 1 != STEP_MAX); + mempool_free(ctx, bio_post_read_ctx_pool); + bio->bi_private = NULL; - bio_post_read_processing(ctx); + fsverity_verify_bio(bio); + + __read_end_io(bio); } static void bio_post_read_processing(struct bio_post_read_ctx *ctx)