Commit c9af28fd authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4 crypto: don't let data integrity writebacks fail with ENOMEM 



We don't want the writeback triggered from the journal commit (in
data=writeback mode) to cause the journal to abort due to
generic_writepages() returning an ENOMEM error.  In addition, if
fsync() fails with ENOMEM, most applications will probably not do the
right thing.

So if we are doing a data integrity sync, and ext4_encrypt() returns
ENOMEM, we will submit any queued I/O to date, and then retry the
allocation using GFP_NOFAIL.

Google-Bug-Id: 27641567

Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 9e92f48c

fs/ext4/crypto.c

+21 −16
Original line number Diff line number Diff line
@@ -91,7 +91,8 @@ void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx) 
 * Return: An allocated and initialized encryption context on success; error

 * value or NULL otherwise.

 */

struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode)

struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode,

					    gfp_t gfp_flags)

{

	struct ext4_crypto_ctx *ctx = NULL;

	int res = 0;
@@ -118,7 +119,7 @@ struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode) 
		list_del(&ctx->free_list);

	spin_unlock_irqrestore(&ext4_crypto_ctx_lock, flags);

	if (!ctx) {

		ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, GFP_NOFS);

		ctx = kmem_cache_zalloc(ext4_crypto_ctx_cachep, gfp_flags);

		if (!ctx) {

			res = -ENOMEM;

			goto out;
@@ -255,7 +256,8 @@ static int ext4_page_crypto(struct inode *inode, 
			    ext4_direction_t rw,

			    pgoff_t index,

			    struct page *src_page,

			    struct page *dest_page)

			    struct page *dest_page,

			    gfp_t gfp_flags)



{

	u8 xts_tweak[EXT4_XTS_TWEAK_SIZE];
@@ -266,7 +268,7 @@ static int ext4_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",
@@ -307,9 +309,10 @@ static int ext4_page_crypto(struct inode *inode, 
	return 0;

}



static struct page *alloc_bounce_page(struct ext4_crypto_ctx *ctx)

static struct page *alloc_bounce_page(struct ext4_crypto_ctx *ctx,

				      gfp_t gfp_flags)

{

	ctx->w.bounce_page = mempool_alloc(ext4_bounce_page_pool, GFP_NOWAIT);

	ctx->w.bounce_page = mempool_alloc(ext4_bounce_page_pool, gfp_flags);

	if (ctx->w.bounce_page == NULL)

		return ERR_PTR(-ENOMEM);

	ctx->flags |= EXT4_WRITE_PATH_FL;
@@ -332,7 +335,8 @@ static struct page *alloc_bounce_page(struct ext4_crypto_ctx *ctx) 
 * error value or NULL.

 */

struct page *ext4_encrypt(struct inode *inode,

			  struct page *plaintext_page)

			  struct page *plaintext_page,

			  gfp_t gfp_flags)

{

	struct ext4_crypto_ctx *ctx;

	struct page *ciphertext_page = NULL;
@@ -340,17 +344,17 @@ struct page *ext4_encrypt(struct inode *inode, 


	BUG_ON(!PageLocked(plaintext_page));



	ctx = ext4_get_crypto_ctx(inode);

	ctx = ext4_get_crypto_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 = ext4_page_crypto(inode, EXT4_ENCRYPT, plaintext_page->index,

			       plaintext_page, ciphertext_page);

			       plaintext_page, ciphertext_page, gfp_flags);

	if (err) {

		ciphertext_page = ERR_PTR(err);

	errout:
@@ -378,8 +382,8 @@ int ext4_decrypt(struct page *page) 
{

	BUG_ON(!PageLocked(page));



	return ext4_page_crypto(page->mapping->host,

				EXT4_DECRYPT, page->index, page, page);

	return ext4_page_crypto(page->mapping->host, EXT4_DECRYPT,

				page->index, page, page, GFP_NOFS);

}



int ext4_encrypted_zeroout(struct inode *inode, ext4_lblk_t lblk,
@@ -398,11 +402,11 @@ int ext4_encrypted_zeroout(struct inode *inode, ext4_lblk_t lblk, 


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



	ctx = ext4_get_crypto_ctx(inode);

	ctx = ext4_get_crypto_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;
@@ -410,11 +414,12 @@ int ext4_encrypted_zeroout(struct inode *inode, ext4_lblk_t lblk, 


	while (len--) {

		err = ext4_page_crypto(inode, EXT4_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;

fs/ext4/ext4.h

+4 −2
Original line number Diff line number Diff line
@@ -2282,11 +2282,13 @@ extern struct kmem_cache *ext4_crypt_info_cachep; 
bool ext4_valid_contents_enc_mode(uint32_t mode);

uint32_t ext4_validate_encryption_key_size(uint32_t mode, uint32_t size);

extern struct workqueue_struct *ext4_read_workqueue;

struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode);

struct ext4_crypto_ctx *ext4_get_crypto_ctx(struct inode *inode,

					    gfp_t gfp_flags);

void ext4_release_crypto_ctx(struct ext4_crypto_ctx *ctx);

void ext4_restore_control_page(struct page *data_page);

struct page *ext4_encrypt(struct inode *inode,

			  struct page *plaintext_page);

			  struct page *plaintext_page,

			  gfp_t gfp_flags);

int ext4_decrypt(struct page *page);

int ext4_encrypted_zeroout(struct inode *inode, ext4_lblk_t lblk,

			   ext4_fsblk_t pblk, ext4_lblk_t len);

fs/ext4/page-io.c

+13 −1
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/kernel.h>

#include <linux/slab.h>

#include <linux/mm.h>

#include <linux/backing-dev.h>



#include "ext4_jbd2.h"

#include "xattr.h"
@@ -470,9 +471,20 @@ int ext4_bio_write_page(struct ext4_io_submit *io, 


	if (ext4_encrypted_inode(inode) && S_ISREG(inode->i_mode) &&

	    nr_to_submit) {

		data_page = ext4_encrypt(inode, page);

		gfp_t gfp_flags = GFP_NOFS;



	retry_encrypt:

		data_page = ext4_encrypt(inode, page, gfp_flags);

		if (IS_ERR(data_page)) {

			ret = PTR_ERR(data_page);

			if (ret == ENOMEM && wbc->sync_mode == WB_SYNC_ALL) {

				if (io->io_bio) {

					ext4_io_submit(io);

					congestion_wait(BLK_RW_ASYNC, HZ/50);

				}

				gfp_flags |= __GFP_NOFAIL;

				goto retry_encrypt;

			}

			data_page = NULL;

			goto out;

		}

fs/ext4/readpage.c

+1 −1
Original line number Diff line number Diff line
@@ -279,7 +279,7 @@ int ext4_mpage_readpages(struct address_space *mapping, 


			if (ext4_encrypted_inode(inode) &&

			    S_ISREG(inode->i_mode)) {

				ctx = ext4_get_crypto_ctx(inode);

				ctx = ext4_get_crypto_ctx(inode, GFP_NOFS);

				if (IS_ERR(ctx))

					goto set_error_page;

			}

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