From: Eric Biggers <ebiggers@google.com>
Date: Mon, 25 Sep 2023 05:54:48 +0000 (-0700)
Subject: fscrypt: make the bounce page pool opt-in instead of opt-out
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=40e13e18168fd0f1a6ad10166f5042a21c47ab99;p=linux.git
fscrypt: make the bounce page pool opt-in instead of opt-out
Replace FS_CFLG_OWN_PAGES with a bit flag 'needs_bounce_pages' which has
the opposite meaning. I.e., filesystems now opt into the bounce page
pool instead of opt out. Make fscrypt_alloc_bounce_page() check that
the bounce page pool has been initialized.
I believe the opt-in makes more sense, since nothing else in
fscrypt_operations is opt-out, and these days filesystems can choose to
use blk-crypto which doesn't need the fscrypt bounce page pool. Also, I
happen to be planning to add two more flags, and I wanted to fix the
"FS_CFLG_" name anyway as it wasn't prefixed with "FSCRYPT_".
Link: https://lore.kernel.org/r/20230925055451.59499-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c
index e4d5cd56a80b9..cc63f1e6fdef6 100644
--- a/fs/ceph/crypto.c
+++ b/fs/ceph/crypto.c
@@ -133,6 +133,7 @@ static const union fscrypt_policy *ceph_get_dummy_policy(struct super_block *sb)
}
static struct fscrypt_operations ceph_fscrypt_ops = {
+ .needs_bounce_pages = 1,
.get_context = ceph_crypt_get_context,
.set_context = ceph_crypt_set_context,
.get_dummy_policy = ceph_get_dummy_policy,
diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 6a837e4b80dcb..aed0c5ea75781 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -49,6 +49,13 @@ EXPORT_SYMBOL(fscrypt_enqueue_decrypt_work);
struct page *fscrypt_alloc_bounce_page(gfp_t gfp_flags)
{
+ if (WARN_ON_ONCE(!fscrypt_bounce_page_pool)) {
+ /*
+ * Oops, the filesystem called a function that uses the bounce
+ * page pool, but it didn't set needs_bounce_pages.
+ */
+ return NULL;
+ }
return mempool_alloc(fscrypt_bounce_page_pool, gfp_flags);
}
@@ -325,7 +332,7 @@ int fscrypt_initialize(struct super_block *sb)
return 0;
/* No need to allocate a bounce page pool if this FS won't use it. */
- if (sb->s_cop->flags & FS_CFLG_OWN_PAGES)
+ if (!sb->s_cop->needs_bounce_pages)
return 0;
mutex_lock(&fscrypt_init_mutex);
diff --git a/fs/ext4/crypto.c b/fs/ext4/crypto.c
index 99a4769a53f63..5cd7bcfae46b2 100644
--- a/fs/ext4/crypto.c
+++ b/fs/ext4/crypto.c
@@ -240,6 +240,7 @@ static void ext4_get_ino_and_lblk_bits(struct super_block *sb,
}
const struct fscrypt_operations ext4_cryptops = {
+ .needs_bounce_pages = 1,
.legacy_key_prefix = "ext4:",
.get_context = ext4_get_context,
.set_context = ext4_set_context,
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index f60062b558fd1..55aa0ed531f22 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -3231,6 +3231,7 @@ static struct block_device **f2fs_get_devices(struct super_block *sb,
}
static const struct fscrypt_operations f2fs_cryptops = {
+ .needs_bounce_pages = 1,
.legacy_key_prefix = "f2fs:",
.get_context = f2fs_get_context,
.set_context = f2fs_set_context,
diff --git a/fs/ubifs/crypto.c b/fs/ubifs/crypto.c
index 1be3e11da3b3e..921f9033d0d2d 100644
--- a/fs/ubifs/crypto.c
+++ b/fs/ubifs/crypto.c
@@ -88,7 +88,6 @@ int ubifs_decrypt(const struct inode *inode, struct ubifs_data_node *dn,
}
const struct fscrypt_operations ubifs_crypt_operations = {
- .flags = FS_CFLG_OWN_PAGES,
.legacy_key_prefix = "ubifs:",
.get_context = ubifs_crypt_get_context,
.set_context = ubifs_crypt_set_context,
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index b0037566ce308..4505078e89b7e 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -59,18 +59,20 @@ struct fscrypt_name {
#ifdef CONFIG_FS_ENCRYPTION
-/*
- * If set, the fscrypt bounce page pool won't be allocated (unless another
- * filesystem needs it). Set this if the filesystem always uses its own bounce
- * pages for writes and therefore won't need the fscrypt bounce page pool.
- */
-#define FS_CFLG_OWN_PAGES (1U << 1)
-
/* Crypto operations for filesystems */
struct fscrypt_operations {
- /* Set of optional flags; see above for allowed flags */
- unsigned int flags;
+ /*
+ * If set, then fs/crypto/ will allocate a global bounce page pool the
+ * first time an encryption key is set up for a file. The bounce page
+ * pool is required by the following functions:
+ *
+ * - fscrypt_encrypt_pagecache_blocks()
+ * - fscrypt_zeroout_range() for files not using inline crypto
+ *
+ * If the filesystem doesn't use those, it doesn't need to set this.
+ */
+ unsigned int needs_bounce_pages : 1;
/*
* This field exists only for backwards compatibility reasons and should