This patch applies the following ext4 patch:
ext4 crypto: use per-inode tfm structure
As suggested by Herbert Xu, we shouldn't allocate a new tfm each time
we read or write a page. Instead we can use a single tfm hanging off
the inode's crypt_info structure for all of our encryption needs for
that inode, since the tfm can be used by multiple crypto requests in
parallel.
Also use cmpxchg() to avoid races that could result in crypt_info
structure getting doubly allocated or doubly freed.
Signed-off-by: Theodore Ts'o <[email protected]>
Signed-off-by: Jaegeuk Kim <[email protected]>
---
fs/f2fs/crypto.c | 82 +++----------------------------------
fs/f2fs/crypto_fname.c | 48 +---------------------
fs/f2fs/crypto_key.c | 107 ++++++++++++++++++++++++++++++++++++-------------
fs/f2fs/dir.c | 8 ++--
fs/f2fs/f2fs.h | 5 +--
fs/f2fs/f2fs_crypto.h | 4 --
fs/f2fs/inode.c | 2 +-
fs/f2fs/namei.c | 4 +-
fs/f2fs/super.c | 3 +-
9 files changed, 96 insertions(+), 167 deletions(-)
diff --git a/fs/f2fs/crypto.c b/fs/f2fs/crypto.c
index c6d1122..2c7819a 100644
--- a/fs/f2fs/crypto.c
+++ b/fs/f2fs/crypto.c
@@ -91,8 +91,6 @@ void f2fs_release_crypto_ctx(struct f2fs_crypto_ctx *ctx)
}
ctx->w.control_page = NULL;
if (ctx->flags & F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL) {
- if (ctx->tfm)
- crypto_free_tfm(ctx->tfm);
kmem_cache_free(f2fs_crypto_ctx_cachep, ctx);
} else {
spin_lock_irqsave(&f2fs_crypto_ctx_lock, flags);
@@ -113,7 +111,6 @@ void f2fs_release_crypto_ctx(struct f2fs_crypto_ctx *ctx)
struct f2fs_crypto_ctx *f2fs_get_crypto_ctx(struct inode *inode)
{
struct f2fs_crypto_ctx *ctx = NULL;
- int res = 0;
unsigned long flags;
struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
@@ -138,56 +135,13 @@ struct f2fs_crypto_ctx *f2fs_get_crypto_ctx(struct inode *inode)
spin_unlock_irqrestore(&f2fs_crypto_ctx_lock, flags);
if (!ctx) {
ctx = kmem_cache_zalloc(f2fs_crypto_ctx_cachep, GFP_NOFS);
- if (!ctx) {
- res = -ENOMEM;
- goto out;
- }
+ if (!ctx)
+ return ERR_PTR(-ENOMEM);
ctx->flags |= F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
} else {
ctx->flags &= ~F2FS_CTX_REQUIRES_FREE_ENCRYPT_FL;
}
ctx->flags &= ~F2FS_WRITE_PATH_FL;
-
- /*
- * Allocate a new Crypto API context if we don't already have
- * one or if it isn't the right mode.
- */
- if (ctx->tfm && (ctx->mode != ci->ci_data_mode)) {
- crypto_free_tfm(ctx->tfm);
- ctx->tfm = NULL;
- ctx->mode = F2FS_ENCRYPTION_MODE_INVALID;
- }
- if (!ctx->tfm) {
- switch (ci->ci_data_mode) {
- case F2FS_ENCRYPTION_MODE_AES_256_XTS:
- ctx->tfm = crypto_ablkcipher_tfm(
- crypto_alloc_ablkcipher("xts(aes)", 0, 0));
- break;
- case F2FS_ENCRYPTION_MODE_AES_256_GCM:
- /*
- * TODO(mhalcrow): AEAD w/ gcm(aes);
- * crypto_aead_setauthsize()
- */
- ctx->tfm = ERR_PTR(-ENOTSUPP);
- break;
- default:
- BUG();
- }
- if (IS_ERR_OR_NULL(ctx->tfm)) {
- res = PTR_ERR(ctx->tfm);
- ctx->tfm = NULL;
- goto out;
- }
- ctx->mode = ci->ci_data_mode;
- }
- BUG_ON(ci->ci_size != f2fs_encryption_key_size(ci->ci_data_mode));
-
-out:
- if (res) {
- if (!IS_ERR_OR_NULL(ctx))
- f2fs_release_crypto_ctx(ctx);
- ctx = ERR_PTR(res);
- }
return ctx;
}
@@ -229,11 +183,8 @@ static void f2fs_crypto_destroy(void)
{
struct f2fs_crypto_ctx *pos, *n;
- list_for_each_entry_safe(pos, n, &f2fs_free_crypto_ctxs, free_list) {
- if (pos->tfm)
- crypto_free_tfm(pos->tfm);
+ list_for_each_entry_safe(pos, n, &f2fs_free_crypto_ctxs, free_list)
kmem_cache_free(f2fs_crypto_ctx_cachep, pos);
- }
INIT_LIST_HEAD(&f2fs_free_crypto_ctxs);
if (f2fs_bounce_page_pool)
mempool_destroy(f2fs_bounce_page_pool);
@@ -383,32 +334,11 @@ static int f2fs_page_crypto(struct f2fs_crypto_ctx *ctx,
struct ablkcipher_request *req = NULL;
DECLARE_F2FS_COMPLETION_RESULT(ecr);
struct scatterlist dst, src;
- struct f2fs_inode_info *fi = F2FS_I(inode);
- struct crypto_ablkcipher *atfm = __crypto_ablkcipher_cast(ctx->tfm);
+ struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
+ struct crypto_ablkcipher *tfm = ci->ci_ctfm;
int res = 0;
- BUG_ON(!ctx->tfm);
- BUG_ON(ctx->mode != fi->i_crypt_info->ci_data_mode);
-
- if (ctx->mode != F2FS_ENCRYPTION_MODE_AES_256_XTS) {
- printk_ratelimited(KERN_ERR
- "%s: unsupported crypto algorithm: %d\n",
- __func__, ctx->mode);
- return -ENOTSUPP;
- }
-
- crypto_ablkcipher_clear_flags(atfm, ~0);
- crypto_tfm_set_flags(ctx->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
-
- res = crypto_ablkcipher_setkey(atfm, fi->i_crypt_info->ci_raw,
- fi->i_crypt_info->ci_size);
- if (res) {
- printk_ratelimited(KERN_ERR
- "%s: crypto_ablkcipher_setkey() failed\n",
- __func__);
- return res;
- }
- req = ablkcipher_request_alloc(atfm, GFP_NOFS);
+ req = ablkcipher_request_alloc(tfm, GFP_NOFS);
if (!req) {
printk_ratelimited(KERN_ERR
"%s: crypto_request_alloc() failed\n",
diff --git a/fs/f2fs/crypto_fname.c b/fs/f2fs/crypto_fname.c
index 016c4b6..81852cc 100644
--- a/fs/f2fs/crypto_fname.c
+++ b/fs/f2fs/crypto_fname.c
@@ -249,52 +249,6 @@ static int digest_decode(const char *src, int len, char *dst)
return cp - dst;
}
-int f2fs_setup_fname_crypto(struct inode *inode)
-{
- struct f2fs_inode_info *fi = F2FS_I(inode);
- struct f2fs_crypt_info *ci = fi->i_crypt_info;
- struct crypto_ablkcipher *ctfm;
- int res;
-
- /* Check if the crypto policy is set on the inode */
- res = f2fs_encrypted_inode(inode);
- if (res == 0)
- return 0;
-
- res = f2fs_get_encryption_info(inode);
- if (res < 0)
- return res;
- ci = fi->i_crypt_info;
-
- if (!ci || ci->ci_ctfm)
- return 0;
-
- if (ci->ci_filename_mode != F2FS_ENCRYPTION_MODE_AES_256_CTS) {
- printk_once(KERN_WARNING "f2fs: unsupported key mode %d\n",
- ci->ci_filename_mode);
- return -ENOKEY;
- }
-
- ctfm = crypto_alloc_ablkcipher("cts(cbc(aes))", 0, 0);
- if (!ctfm || IS_ERR(ctfm)) {
- res = ctfm ? PTR_ERR(ctfm) : -ENOMEM;
- printk(KERN_DEBUG "%s: error (%d) allocating crypto tfm\n",
- __func__, res);
- return res;
- }
- crypto_ablkcipher_clear_flags(ctfm, ~0);
- crypto_tfm_set_flags(crypto_ablkcipher_tfm(ctfm),
- CRYPTO_TFM_REQ_WEAK_KEY);
-
- res = crypto_ablkcipher_setkey(ctfm, ci->ci_raw, ci->ci_size);
- if (res) {
- crypto_free_ablkcipher(ctfm);
- return -EIO;
- }
- ci->ci_ctfm = ctfm;
- return 0;
-}
-
/**
* f2fs_fname_crypto_round_up() -
*
@@ -427,7 +381,7 @@ int f2fs_fname_setup_filename(struct inode *dir, const struct qstr *iname,
fname->disk_name.len = iname->len;
return 0;
}
- ret = f2fs_setup_fname_crypto(dir);
+ ret = f2fs_get_encryption_info(dir);
if (ret)
return ret;
ci = F2FS_I(dir)->i_crypt_info;
diff --git a/fs/f2fs/crypto_key.c b/fs/f2fs/crypto_key.c
index 8a10569..95b8f93 100644
--- a/fs/f2fs/crypto_key.c
+++ b/fs/f2fs/crypto_key.c
@@ -87,20 +87,31 @@ out:
return res;
}
-void f2fs_free_encryption_info(struct inode *inode)
+static void f2fs_free_crypt_info(struct f2fs_crypt_info *ci)
{
- struct f2fs_inode_info *fi = F2FS_I(inode);
- struct f2fs_crypt_info *ci = fi->i_crypt_info;
-
if (!ci)
return;
if (ci->ci_keyring_key)
key_put(ci->ci_keyring_key);
crypto_free_ablkcipher(ci->ci_ctfm);
- memzero_explicit(&ci->ci_raw, sizeof(ci->ci_raw));
kmem_cache_free(f2fs_crypt_info_cachep, ci);
- fi->i_crypt_info = NULL;
+}
+
+void f2fs_free_encryption_info(struct inode *inode, struct f2fs_crypt_info *ci)
+{
+ struct f2fs_inode_info *fi = F2FS_I(inode);
+ struct f2fs_crypt_info *prev;
+
+ if (ci == NULL)
+ ci = ACCESS_ONCE(fi->i_crypt_info);
+ if (ci == NULL)
+ return;
+ prev = cmpxchg(&fi->i_crypt_info, ci, NULL);
+ if (prev != ci)
+ return;
+
+ f2fs_free_crypt_info(ci);
}
int _f2fs_get_encryption_info(struct inode *inode)
@@ -113,17 +124,23 @@ int _f2fs_get_encryption_info(struct inode *inode)
struct f2fs_encryption_key *master_key;
struct f2fs_encryption_context ctx;
struct user_key_payload *ukp;
+ struct crypto_ablkcipher *ctfm;
+ const char *cipher_str;
+ char raw_key[F2FS_MAX_KEY_SIZE];
+ char mode;
int res;
res = f2fs_crypto_initialize();
if (res)
return res;
-
- if (fi->i_crypt_info) {
- if (!fi->i_crypt_info->ci_keyring_key ||
- key_validate(fi->i_crypt_info->ci_keyring_key) == 0)
+retry:
+ crypt_info = ACCESS_ONCE(fi->i_crypt_info);
+ if (crypt_info) {
+ if (!crypt_info->ci_keyring_key ||
+ key_validate(crypt_info->ci_keyring_key) == 0)
return 0;
- f2fs_free_encryption_info(inode);
+ f2fs_free_encryption_info(inode, crypt_info);
+ goto retry;
}
res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
@@ -143,18 +160,30 @@ int _f2fs_get_encryption_info(struct inode *inode)
crypt_info->ci_data_mode = ctx.contents_encryption_mode;
crypt_info->ci_filename_mode = ctx.filenames_encryption_mode;
crypt_info->ci_ctfm = NULL;
+ crypt_info->ci_keyring_key = NULL;
memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor,
sizeof(crypt_info->ci_master_key));
if (S_ISREG(inode->i_mode))
- crypt_info->ci_size =
- f2fs_encryption_key_size(crypt_info->ci_data_mode);
+ mode = crypt_info->ci_data_mode;
else if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
- crypt_info->ci_size =
- f2fs_encryption_key_size(crypt_info->ci_filename_mode);
+ mode = crypt_info->ci_filename_mode;
else
BUG();
- BUG_ON(!crypt_info->ci_size);
+ switch (mode) {
+ case F2FS_ENCRYPTION_MODE_AES_256_XTS:
+ cipher_str = "xts(aes)";
+ break;
+ case F2FS_ENCRYPTION_MODE_AES_256_CTS:
+ cipher_str = "cts(cbc(aes))";
+ break;
+ default:
+ printk_once(KERN_WARNING
+ "f2fs: unsupported key mode %d (ino %u)\n",
+ mode, (unsigned) inode->i_ino);
+ res = -ENOKEY;
+ goto out;
+ }
memcpy(full_key_descriptor, F2FS_KEY_DESC_PREFIX,
F2FS_KEY_DESC_PREFIX_SIZE);
@@ -169,6 +198,7 @@ int _f2fs_get_encryption_info(struct inode *inode)
keyring_key = NULL;
goto out;
}
+ crypt_info->ci_keyring_key = keyring_key;
BUG_ON(keyring_key->type != &key_type_logon);
ukp = ((struct user_key_payload *)keyring_key->payload.data);
if (ukp->datalen != sizeof(struct f2fs_encryption_key)) {
@@ -180,19 +210,40 @@ int _f2fs_get_encryption_info(struct inode *inode)
F2FS_KEY_DERIVATION_NONCE_SIZE);
BUG_ON(master_key->size != F2FS_AES_256_XTS_KEY_SIZE);
res = f2fs_derive_key_aes(ctx.nonce, master_key->raw,
- crypt_info->ci_raw);
-out:
- if (res < 0) {
- if (res == -ENOKEY)
- res = 0;
- kmem_cache_free(f2fs_crypt_info_cachep, crypt_info);
- } else {
- fi->i_crypt_info = crypt_info;
- crypt_info->ci_keyring_key = keyring_key;
- keyring_key = NULL;
+ raw_key);
+ if (res)
+ goto out;
+
+ ctfm = crypto_alloc_ablkcipher(cipher_str, 0, 0);
+ if (!ctfm || IS_ERR(ctfm)) {
+ res = ctfm ? PTR_ERR(ctfm) : -ENOMEM;
+ printk(KERN_DEBUG
+ "%s: error %d (inode %u) allocating crypto tfm\n",
+ __func__, res, (unsigned) inode->i_ino);
+ goto out;
}
- if (keyring_key)
- key_put(keyring_key);
+ crypt_info->ci_ctfm = ctfm;
+ crypto_ablkcipher_clear_flags(ctfm, ~0);
+ crypto_tfm_set_flags(crypto_ablkcipher_tfm(ctfm),
+ CRYPTO_TFM_REQ_WEAK_KEY);
+ res = crypto_ablkcipher_setkey(ctfm, raw_key,
+ f2fs_encryption_key_size(mode));
+ if (res)
+ goto out;
+
+ memzero_explicit(raw_key, sizeof(raw_key));
+ if (cmpxchg(&fi->i_crypt_info, NULL, crypt_info) != NULL) {
+ f2fs_free_crypt_info(crypt_info);
+ goto retry;
+ }
+ return 0;
+
+out:
+ if (res == -ENOKEY && !S_ISREG(inode->i_mode))
+ res = 0;
+
+ f2fs_free_crypt_info(crypt_info);
+ memzero_explicit(raw_key, sizeof(raw_key));
return res;
}
diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
index 3e92376..a34ebd8 100644
--- a/fs/f2fs/dir.c
+++ b/fs/f2fs/dir.c
@@ -825,11 +825,11 @@ static int f2fs_readdir(struct file *file, struct dir_context *ctx)
struct f2fs_str fstr = FSTR_INIT(NULL, 0);
int err = 0;
- err = f2fs_setup_fname_crypto(inode);
- if (err)
- return err;
-
if (f2fs_encrypted_inode(inode)) {
+ err = f2fs_get_encryption_info(inode);
+ if (err)
+ return err;
+
err = f2fs_fname_crypto_alloc_buffer(inode, F2FS_NAME_LEN,
&fstr);
if (err < 0)
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 7e93fcf..70cdf7b 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2016,7 +2016,7 @@ int f2fs_decrypt_one(struct inode *, struct page *);
void f2fs_end_io_crypto_work(struct f2fs_crypto_ctx *, struct bio *);
/* crypto_key.c */
-void f2fs_free_encryption_info(struct inode *);
+void f2fs_free_encryption_info(struct inode *, struct f2fs_crypt_info *);
int _f2fs_get_encryption_info(struct inode *inode);
/* crypto_fname.c */
@@ -2051,7 +2051,6 @@ static inline int f2fs_get_encryption_info(struct inode *inode)
return 0;
}
-int f2fs_setup_fname_crypto(struct inode *);
void f2fs_fname_crypto_free_buffer(struct f2fs_str *);
int f2fs_fname_setup_filename(struct inode *, const struct qstr *,
int lookup, struct f2fs_filename *);
@@ -2065,8 +2064,6 @@ static inline void f2fs_exit_crypto(void) { }
static inline int f2fs_has_encryption_key(struct inode *i) { return 0; }
static inline int f2fs_get_encryption_info(struct inode *i) { return 0; }
-
-static inline int f2fs_setup_fname_crypto(struct inode *i) { return 0; }
static inline void f2fs_fname_crypto_free_buffer(struct f2fs_str *p) { }
static inline int f2fs_fname_setup_filename(struct inode *dir,
diff --git a/fs/f2fs/f2fs_crypto.h b/fs/f2fs/f2fs_crypto.h
index e33cec9..be59d91 100644
--- a/fs/f2fs/f2fs_crypto.h
+++ b/fs/f2fs/f2fs_crypto.h
@@ -75,13 +75,11 @@ struct f2fs_encryption_key {
} __attribute__((__packed__));
struct f2fs_crypt_info {
- unsigned char ci_size;
char ci_data_mode;
char ci_filename_mode;
char ci_flags;
struct crypto_ablkcipher *ci_ctfm;
struct key *ci_keyring_key;
- char ci_raw[F2FS_MAX_KEY_SIZE];
char ci_master_key[F2FS_KEY_DESCRIPTOR_SIZE];
};
@@ -90,7 +88,6 @@ struct f2fs_crypt_info {
#define F2FS_WRITE_PATH_FL 0x00000004
struct f2fs_crypto_ctx {
- struct crypto_tfm *tfm; /* Crypto API context */
union {
struct {
struct page *bounce_page; /* Ciphertext page */
@@ -103,7 +100,6 @@ struct f2fs_crypto_ctx {
struct list_head free_list; /* Free list */
};
char flags; /* Flags */
- char mode; /* Encryption mode for tfm */
};
struct f2fs_completion_result {
diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c
index ea6ba3b..2550868 100644
--- a/fs/f2fs/inode.c
+++ b/fs/f2fs/inode.c
@@ -364,7 +364,7 @@ no_delete:
out_clear:
#ifdef CONFIG_F2FS_FS_ENCRYPTION
if (F2FS_I(inode)->i_crypt_info)
- f2fs_free_encryption_info(inode);
+ f2fs_free_encryption_info(inode, F2FS_I(inode)->i_crypt_info);
#endif
clear_inode(inode);
}
diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index 26e68ad..daed09c 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -364,7 +364,7 @@ static int f2fs_symlink(struct inode *dir, struct dentry *dentry,
if (err)
goto err_out;
- err = f2fs_setup_fname_crypto(inode);
+ err = f2fs_get_encryption_info(inode);
if (err)
goto err_out;
@@ -927,7 +927,7 @@ static void *f2fs_encrypted_follow_link(struct dentry *dentry,
u32 max_size = inode->i_sb->s_blocksize;
int res;
- res = f2fs_setup_fname_crypto(inode);
+ res = f2fs_get_encryption_info(inode);
if (res)
return ERR_PTR(res);
diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index f596b24..38bb7c6 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -449,7 +449,8 @@ static int f2fs_drop_inode(struct inode *inode)
#ifdef CONFIG_F2FS_FS_ENCRYPTION
if (F2FS_I(inode)->i_crypt_info)
- f2fs_free_encryption_info(inode);
+ f2fs_free_encryption_info(inode,
+ F2FS_I(inode)->i_crypt_info);
#endif
spin_lock(&inode->i_lock);
}
--
2.1.1
If a lot of write streams are triggered, alloc_page and __free_page are
costly called, resulting in high memory pressure.
In order to avoid that, let's reuse mempool pages for writeback pages.
Signed-off-by: Jaegeuk Kim <[email protected]>
---
fs/f2fs/crypto.c | 16 ++++------------
1 file changed, 4 insertions(+), 12 deletions(-)
diff --git a/fs/f2fs/crypto.c b/fs/f2fs/crypto.c
index 2c7819a..2ceee68 100644
--- a/fs/f2fs/crypto.c
+++ b/fs/f2fs/crypto.c
@@ -408,20 +408,12 @@ struct page *f2fs_encrypt(struct inode *inode,
return (struct page *)ctx;
/* The encryption operation will require a bounce page. */
- ciphertext_page = alloc_page(GFP_NOFS);
+ ciphertext_page = mempool_alloc(f2fs_bounce_page_pool, GFP_NOFS);
if (!ciphertext_page) {
- /*
- * This is a potential bottleneck, but at least we'll have
- * forward progress.
- */
- ciphertext_page = mempool_alloc(f2fs_bounce_page_pool,
- GFP_NOFS);
- if (WARN_ON_ONCE(!ciphertext_page))
- ciphertext_page = mempool_alloc(f2fs_bounce_page_pool,
- GFP_NOFS | __GFP_WAIT);
- ctx->flags &= ~F2FS_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
- } else {
+ ciphertext_page = alloc_page(GFP_NOFS);
ctx->flags |= F2FS_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
+ } else {
+ ctx->flags &= ~F2FS_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
}
ctx->flags |= F2FS_WRITE_PATH_FL;
ctx->w.bounce_page = ciphertext_page;
--
2.1.1
This patch changes the number of preallocated pages to BIO_MAX_PAGES to prepare
writeback encryption.
Signed-off-by: Jaegeuk Kim <[email protected]>
---
fs/f2fs/crypto.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/fs/f2fs/crypto.c b/fs/f2fs/crypto.c
index 2ceee68..cfe5a04 100644
--- a/fs/f2fs/crypto.c
+++ b/fs/f2fs/crypto.c
@@ -48,7 +48,7 @@
/* Encryption added and removed here! (L: */
-static unsigned int num_prealloc_crypto_pages = 32;
+static unsigned int num_prealloc_crypto_pages = BIO_MAX_PAGES;
static unsigned int num_prealloc_crypto_ctxs = 128;
module_param(num_prealloc_crypto_pages, uint, 0444);
--
2.1.1
Hi Jaegeuk,
> -----Original Message-----
> From: Jaegeuk Kim [mailto:[email protected]]
> Sent: Friday, May 22, 2015 8:40 AM
> To: [email protected]; [email protected];
> [email protected]
> Cc: Jaegeuk Kim
> Subject: [f2fs-dev] [PATCH 2/3] f2fs crypto: use bounce pages from mempool first
>
> If a lot of write streams are triggered, alloc_page and __free_page are
> costly called, resulting in high memory pressure.
>
> In order to avoid that, let's reuse mempool pages for writeback pages.
>
> Signed-off-by: Jaegeuk Kim <[email protected]>
> ---
> fs/f2fs/crypto.c | 16 ++++------------
> 1 file changed, 4 insertions(+), 12 deletions(-)
>
> diff --git a/fs/f2fs/crypto.c b/fs/f2fs/crypto.c
> index 2c7819a..2ceee68 100644
> --- a/fs/f2fs/crypto.c
> +++ b/fs/f2fs/crypto.c
> @@ -408,20 +408,12 @@ struct page *f2fs_encrypt(struct inode *inode,
> return (struct page *)ctx;
>
> /* The encryption operation will require a bounce page. */
> - ciphertext_page = alloc_page(GFP_NOFS);
> + ciphertext_page = mempool_alloc(f2fs_bounce_page_pool, GFP_NOFS);
> if (!ciphertext_page) {
> - /*
> - * This is a potential bottleneck, but at least we'll have
> - * forward progress.
> - */
> - ciphertext_page = mempool_alloc(f2fs_bounce_page_pool,
> - GFP_NOFS);
> - if (WARN_ON_ONCE(!ciphertext_page))
> - ciphertext_page = mempool_alloc(f2fs_bounce_page_pool,
> - GFP_NOFS | __GFP_WAIT);
> - ctx->flags &= ~F2FS_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
> - } else {
> + ciphertext_page = alloc_page(GFP_NOFS);
Using alloc_page(GFP_NOFS | __GFP_WAIT) to avoid failure?
Thanks,
> ctx->flags |= F2FS_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
> + } else {
> + ctx->flags &= ~F2FS_BOUNCE_PAGE_REQUIRES_FREE_ENCRYPT_FL;
> }
> ctx->flags |= F2FS_WRITE_PATH_FL;
> ctx->w.bounce_page = ciphertext_page;
> --
> 2.1.1
>
>
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On Thu, May 21, 2015 at 05:40:24PM -0700, Jaegeuk Kim wrote:
> If a lot of write streams are triggered, alloc_page and __free_page are
> costly called, resulting in high memory pressure.
>
> In order to avoid that, let's reuse mempool pages for writeback pages.
The reason why the mempool pages was used as a fallback was because
once we are deep in the writeback code, handling memory allocation
failures is close to impossible, since we've already made enough
changes that unwinding them would be extremely difficult. So the
basic idea was to use the mempool as an emergency reserve, since
Failure Is Not An Option, and the alternative, which is to simply loop
until the mm subsystem sees fit to give us a page, has sometimes led
to deadlock.
The primary source of write streams should be either (a) fsync
operations, or (b) calls from the writeback thread. Are there any
additional sources for f2fs? If they are calls from fsync operations,
and we have more than a threshold number of write operations in play,
we might want to think about blocking the fsync/fdatasync writeback,
**before** the operation starts taking locks, so other write
operations can proceed. And the writeback thread should keep the
number of write operations to a reasonable number, especially given
that we are treating page encryption as a blocking operation. Or is
there something else going on which is making this to be more of a
problem for f2fs?
Regards,
- Ted