[PATCH 3/3] fscrypto: don't let data integrity writebacks fail with ENOMEM

From: Jaegeuk Kim
Date: Tue Apr 12 2016 - 13:27:36 EST

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This patch fixes the issue introduced by the ext4 crypto fix in a same manner.
For F2FS, however, we flush the pending IOs and wait for a while to acquire free
memory.

Fixes: c9af28fdd4492 ("ext4 crypto: don't let data integrity writebacks fail with ENOMEM")
Cc: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
---
fs/crypto/crypto.c | 36 ++++++++++++++++++++----------------
fs/f2fs/data.c | 16 +++++++++++++---
include/linux/fscrypto.h | 9 +++++----
3 files changed, 38 insertions(+), 23 deletions(-)

diff --git a/fs/crypto/crypto.c b/fs/crypto/crypto.c
index 58ae0ba..da70520 100644
--- a/fs/crypto/crypto.c
+++ b/fs/crypto/crypto.c
@@ -81,13 +81,14 @@ EXPORT_SYMBOL(fscrypt_release_ctx);
/**
* fscrypt_get_ctx() - Gets an encryption context
* @inode: The inode for which we are doing the crypto
+ * @gfp_flags: The gfp flag for memory allocation
*
* Allocates and initializes an encryption context.
*
* Return: An allocated and initialized encryption context on success; error
* value or NULL otherwise.
*/
-struct fscrypt_ctx *fscrypt_get_ctx(struct inode *inode)
+struct fscrypt_ctx *fscrypt_get_ctx(struct inode *inode, gfp_t gfp_flags)
{
struct fscrypt_ctx *ctx = NULL;
struct fscrypt_info *ci = inode->i_crypt_info;
@@ -113,7 +114,7 @@ struct fscrypt_ctx *fscrypt_get_ctx(struct inode *inode)
list_del(&ctx->free_list);
spin_unlock_irqrestore(&fscrypt_ctx_lock, flags);
if (!ctx) {
- ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, GFP_NOFS);
+ ctx = kmem_cache_zalloc(fscrypt_ctx_cachep, gfp_flags);
if (!ctx)
return ERR_PTR(-ENOMEM);
ctx->flags |= FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
@@ -147,7 +148,8 @@ typedef enum {

static int do_page_crypto(struct inode *inode,
fscrypt_direction_t rw, pgoff_t index,
- struct page *src_page, struct page *dest_page)
+ struct page *src_page, struct page *dest_page,
+ gfp_t gfp_flags)
{
u8 xts_tweak[FS_XTS_TWEAK_SIZE];
struct skcipher_request *req = NULL;
@@ -157,7 +159,7 @@ static int do_page_crypto(struct inode *inode,
struct crypto_skcipher *tfm = ci->ci_ctfm;
int res = 0;

- req = skcipher_request_alloc(tfm, GFP_NOFS);
+ req = skcipher_request_alloc(tfm, gfp_flags);
if (!req) {
printk_ratelimited(KERN_ERR
"%s: crypto_request_alloc() failed\n",
@@ -199,10 +201,9 @@ static int do_page_crypto(struct inode *inode,
return 0;
}

-static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx)
+static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx, gfp_t gfp_flags)
{
- ctx->w.bounce_page = mempool_alloc(fscrypt_bounce_page_pool,
- GFP_NOWAIT);
+ ctx->w.bounce_page = mempool_alloc(fscrypt_bounce_page_pool, gfp_flags);
if (ctx->w.bounce_page == NULL)
return ERR_PTR(-ENOMEM);
ctx->flags |= FS_WRITE_PATH_FL;
@@ -213,6 +214,7 @@ static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx)
* fscypt_encrypt_page() - Encrypts a page
* @inode: The inode for which the encryption should take place
* @plaintext_page: The page to encrypt. Must be locked.
+ * @gfp_flags: The gfp flag for memory allocation
*
* Allocates a ciphertext page and encrypts plaintext_page into it using the ctx
* encryption context.
@@ -225,7 +227,7 @@ static struct page *alloc_bounce_page(struct fscrypt_ctx *ctx)
* error value or NULL.
*/
struct page *fscrypt_encrypt_page(struct inode *inode,
- struct page *plaintext_page)
+ struct page *plaintext_page, gfp_t gfp_flags)
{
struct fscrypt_ctx *ctx;
struct page *ciphertext_page = NULL;
@@ -233,18 +235,19 @@ struct page *fscrypt_encrypt_page(struct inode *inode,

BUG_ON(!PageLocked(plaintext_page));

- ctx = fscrypt_get_ctx(inode);
+ ctx = fscrypt_get_ctx(inode, gfp_flags);
if (IS_ERR(ctx))
return (struct page *)ctx;

/* The encryption operation will require a bounce page. */
- ciphertext_page = alloc_bounce_page(ctx);
+ ciphertext_page = alloc_bounce_page(ctx, gfp_flags);
if (IS_ERR(ciphertext_page))
goto errout;

ctx->w.control_page = plaintext_page;
err = do_page_crypto(inode, FS_ENCRYPT, plaintext_page->index,
- plaintext_page, ciphertext_page);
+ plaintext_page, ciphertext_page,
+ gfp_flags);
if (err) {
ciphertext_page = ERR_PTR(err);
goto errout;
@@ -275,7 +278,7 @@ int fscrypt_decrypt_page(struct page *page)
BUG_ON(!PageLocked(page));

return do_page_crypto(page->mapping->host,
- FS_DECRYPT, page->index, page, page);
+ FS_DECRYPT, page->index, page, page, GFP_NOFS);
}
EXPORT_SYMBOL(fscrypt_decrypt_page);

@@ -289,11 +292,11 @@ int fscrypt_zeroout_range(struct inode *inode, pgoff_t lblk,

BUG_ON(inode->i_sb->s_blocksize != PAGE_SIZE);

- ctx = fscrypt_get_ctx(inode);
+ ctx = fscrypt_get_ctx(inode, GFP_NOFS);
if (IS_ERR(ctx))
return PTR_ERR(ctx);

- ciphertext_page = alloc_bounce_page(ctx);
+ ciphertext_page = alloc_bounce_page(ctx, GFP_NOWAIT);
if (IS_ERR(ciphertext_page)) {
err = PTR_ERR(ciphertext_page);
goto errout;
@@ -301,11 +304,12 @@ int fscrypt_zeroout_range(struct inode *inode, pgoff_t lblk,

while (len--) {
err = do_page_crypto(inode, FS_ENCRYPT, lblk,
- ZERO_PAGE(0), ciphertext_page);
+ ZERO_PAGE(0), ciphertext_page,
+ GFP_NOFS);
if (err)
goto errout;

- bio = bio_alloc(GFP_KERNEL, 1);
+ bio = bio_alloc(GFP_NOWAIT, 1);
if (!bio) {
err = -ENOMEM;
goto errout;
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 53fec08..5dafb9c 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -992,7 +992,7 @@ submit_and_realloc:
if (f2fs_encrypted_inode(inode) &&
S_ISREG(inode->i_mode)) {

- ctx = fscrypt_get_ctx(inode);
+ ctx = fscrypt_get_ctx(inode, GFP_NOFS);
if (IS_ERR(ctx))
goto set_error_page;

@@ -1092,14 +1092,24 @@ int do_write_data_page(struct f2fs_io_info *fio)
}

if (f2fs_encrypted_inode(inode) && S_ISREG(inode->i_mode)) {
+ gfp_t gfp_flags = GFP_NOFS;

/* wait for GCed encrypted page writeback */
f2fs_wait_on_encrypted_page_writeback(F2FS_I_SB(inode),
fio->old_blkaddr);
-
- fio->encrypted_page = fscrypt_encrypt_page(inode, fio->page);
+retry_encrypt:
+ fio->encrypted_page = fscrypt_encrypt_page(inode, fio->page,
+ gfp_flags);
if (IS_ERR(fio->encrypted_page)) {
err = PTR_ERR(fio->encrypted_page);
+ if (err == -ENOMEM) {
+ /* flush pending ios and wait for a while */
+ f2fs_flush_merged_bios(F2FS_I_SB(inode));
+ congestion_wait(BLK_RW_ASYNC, HZ/50);
+ gfp_flags |= __GFP_NOFAIL;
+ err = 0;
+ goto retry_encrypt;
+ }
goto out_writepage;
}
}
diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h
index cd91f75..6027f6b 100644
--- a/include/linux/fscrypto.h
+++ b/include/linux/fscrypto.h
@@ -263,9 +263,9 @@ static inline void fscrypt_set_d_op(struct dentry *dentry)
extern struct kmem_cache *fscrypt_info_cachep;
int fscrypt_initialize(void);

-extern struct fscrypt_ctx *fscrypt_get_ctx(struct inode *);
+extern struct fscrypt_ctx *fscrypt_get_ctx(struct inode *, gfp_t);
extern void fscrypt_release_ctx(struct fscrypt_ctx *);
-extern struct page *fscrypt_encrypt_page(struct inode *, struct page *);
+extern struct page *fscrypt_encrypt_page(struct inode *, struct page *, gfp_t);
extern int fscrypt_decrypt_page(struct page *);
extern void fscrypt_decrypt_bio_pages(struct fscrypt_ctx *, struct bio *);
extern void fscrypt_pullback_bio_page(struct page **, bool);
@@ -299,7 +299,8 @@ extern int fscrypt_fname_usr_to_disk(struct inode *, const struct qstr *,
#endif

/* crypto.c */
-static inline struct fscrypt_ctx *fscrypt_notsupp_get_ctx(struct inode *i)
+static inline struct fscrypt_ctx *fscrypt_notsupp_get_ctx(struct inode *i,
+ gfp_t f)
{
return ERR_PTR(-EOPNOTSUPP);
}
@@ -310,7 +311,7 @@ static inline void fscrypt_notsupp_release_ctx(struct fscrypt_ctx *c)
}

static inline struct page *fscrypt_notsupp_encrypt_page(struct inode *i,
- struct page *p)
+ struct page *p, gfp_t f)
{
return ERR_PTR(-EOPNOTSUPP);
}
--
2.6.3

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