f2fs crypto: avoid unneeded memory allocation when {en/de}crypting symlink

This patch adopts f2fs with codes of ext4, it removes unneeded memory
allocation in creating/accessing path of symlink.

Signed-off-by: Chao Yu <chao2.yu@samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

3 files changed, 48 insertions, 46 deletions

diff --git a/fs/f2fs/crypto_fname.c b/fs/f2fs/crypto_fname.c
index 73741fb65069..6dfdc978fe45 100644
--- a/fs/f2fs/crypto_fname.c
+++ b/fs/f2fs/crypto_fname.c
@@ -257,6 +257,18 @@ u32 f2fs_fname_crypto_round_up(u32 size, u32 blksize)
         return ((size + blksize - 1) / blksize) * blksize;
 }
 
+unsigned f2fs_fname_encrypted_size(struct inode *inode, u32 ilen)
+{
+        struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
+        int padding = 32;
+
+        if (ci)
+                padding = 4 << (ci->ci_flags & F2FS_POLICY_FLAGS_PAD_MASK);
+        if (ilen < F2FS_CRYPTO_BLOCK_SIZE)
+                ilen = F2FS_CRYPTO_BLOCK_SIZE;
+        return f2fs_fname_crypto_round_up(ilen, padding);
+}
+
 /**
  * f2fs_fname_crypto_alloc_obuff() -
  *
@@ -266,15 +278,8 @@ u32 f2fs_fname_crypto_round_up(u32 size, u32 blksize)
 int f2fs_fname_crypto_alloc_buffer(struct inode *inode,
                                    u32 ilen, struct f2fs_str *crypto_str)
 {
-        unsigned int olen;
-        int padding = 32;
-        struct f2fs_crypt_info *ci = F2FS_I(inode)->i_crypt_info;
+        unsigned int olen = f2fs_fname_encrypted_size(inode, ilen);
 
-        if (ci)
-                padding = 4 << (ci->ci_flags & F2FS_POLICY_FLAGS_PAD_MASK);
-        if (ilen < F2FS_CRYPTO_BLOCK_SIZE)
-                ilen = F2FS_CRYPTO_BLOCK_SIZE;
-        olen = f2fs_fname_crypto_round_up(ilen, padding);
         crypto_str->len = olen;
         if (olen < F2FS_FNAME_CRYPTO_DIGEST_SIZE * 2)
                 olen = F2FS_FNAME_CRYPTO_DIGEST_SIZE * 2;
diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
index 0d2b1ba9660e..f9c294eee0f1 100644
--- a/fs/f2fs/f2fs.h
+++ b/fs/f2fs/f2fs.h
@@ -2226,6 +2226,7 @@ int _f2fs_get_encryption_info(struct inode *inode);
 /* crypto_fname.c */
 bool f2fs_valid_filenames_enc_mode(uint32_t);
 u32 f2fs_fname_crypto_round_up(u32, u32);
+unsigned f2fs_fname_encrypted_size(struct inode *, u32);
 int f2fs_fname_crypto_alloc_buffer(struct inode *, u32, struct f2fs_str *);
 int f2fs_fname_disk_to_usr(struct inode *, f2fs_hash_t *,
                         const struct f2fs_str *, struct f2fs_str *);
diff --git a/fs/f2fs/namei.c b/fs/f2fs/namei.c
index 6f944e5eb76e..fcc8c26c0fe8 100644
--- a/fs/f2fs/namei.c
+++ b/fs/f2fs/namei.c
@@ -345,13 +345,23 @@ static int f2fs_symlink(struct inode *dir, struct dentry *dentry,
         struct f2fs_sb_info *sbi = F2FS_I_SB(dir);
         struct inode *inode;
         size_t len = strlen(symname);
-        size_t p_len;
-        char *p_str;
-        struct f2fs_str disk_link = FSTR_INIT(NULL, 0);
+        struct f2fs_str disk_link = FSTR_INIT((char *)symname, len + 1);
         struct f2fs_encrypted_symlink_data *sd = NULL;
         int err;
 
-        if (len > dir->i_sb->s_blocksize)
+        if (f2fs_encrypted_inode(dir)) {
+                err = f2fs_get_encryption_info(dir);
+                if (err)
+                        return err;
+
+                if (!f2fs_encrypted_inode(dir))
+                        return -EPERM;
+
+                disk_link.len = (f2fs_fname_encrypted_size(dir, len) +
+                                sizeof(struct f2fs_encrypted_symlink_data));
+        }
+
+        if (disk_link.len > dir->i_sb->s_blocksize)
                 return -ENAMETOOLONG;
 
         inode = f2fs_new_inode(dir, S_IFLNK | S_IRWXUGO);
@@ -374,42 +384,36 @@ static int f2fs_symlink(struct inode *dir, struct dentry *dentry,
         f2fs_unlock_op(sbi);
         alloc_nid_done(sbi, inode->i_ino);
 
-        if (f2fs_encrypted_inode(dir)) {
+        if (f2fs_encrypted_inode(inode)) {
                 struct qstr istr = QSTR_INIT(symname, len);
+                struct f2fs_str ostr;
 
-                err = f2fs_get_encryption_info(inode);
-                if (err)
+                sd = kzalloc(disk_link.len, GFP_NOFS);
+                if (!sd) {
+                        err = -ENOMEM;
                         goto err_out;
+                }
 
-                err = f2fs_fname_crypto_alloc_buffer(inode, len, &disk_link);
+                err = f2fs_get_encryption_info(inode);
                 if (err)
                         goto err_out;
 
-                err = f2fs_fname_usr_to_disk(inode, &istr, &disk_link);
-                if (err < 0)
-                        goto err_out;
-
-                p_len = encrypted_symlink_data_len(disk_link.len) + 1;
-
-                if (p_len > dir->i_sb->s_blocksize) {
-                        err = -ENAMETOOLONG;
+                if (!f2fs_encrypted_inode(inode)) {
+                        err = -EPERM;
                         goto err_out;
                 }
 
-                sd = kzalloc(p_len, GFP_NOFS);
-                if (!sd) {
-                        err = -ENOMEM;
+                ostr.name = sd->encrypted_path;
+                ostr.len = disk_link.len;
+                err = f2fs_fname_usr_to_disk(inode, &istr, &ostr);
+                if (err < 0)
                         goto err_out;
-                }
-                memcpy(sd->encrypted_path, disk_link.name, disk_link.len);
-                sd->len = cpu_to_le16(disk_link.len);
-                p_str = (char *)sd;
-        } else {
-                p_len = len + 1;
-                p_str = (char *)symname;
+
+                sd->len = cpu_to_le16(ostr.len);
+                disk_link.name = (char *)sd;
         }
 
-        err = page_symlink(inode, p_str, p_len);
+        err = page_symlink(inode, disk_link.name, disk_link.len);
 
 err_out:
         d_instantiate(dentry, inode);
@@ -425,7 +429,8 @@ err_out:
          * performance regression.
          */
         if (!err) {
-                filemap_write_and_wait_range(inode->i_mapping, 0, p_len - 1);
+                filemap_write_and_wait_range(inode->i_mapping, 0,
+                                                        disk_link.len - 1);
 
                 if (IS_DIRSYNC(dir))
                         f2fs_sync_fs(sbi->sb, 1);
@@ -434,7 +439,6 @@ err_out:
         }
 
         kfree(sd);
-        f2fs_fname_crypto_free_buffer(&disk_link);
         return err;
 out:
         handle_failed_inode(inode);
@@ -966,6 +970,7 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
 
         /* Symlink is encrypted */
         sd = (struct f2fs_encrypted_symlink_data *)caddr;
+        cstr.name = sd->encrypted_path;
         cstr.len = le16_to_cpu(sd->len);
 
         /* this is broken symlink case */
@@ -973,12 +978,6 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
                 res = -ENOENT;
                 goto errout;
         }
-        cstr.name = kmalloc(cstr.len, GFP_NOFS);
-        if (!cstr.name) {
-                res = -ENOMEM;
-                goto errout;
-        }
-        memcpy(cstr.name, sd->encrypted_path, cstr.len);
 
         /* this is broken symlink case */
         if (unlikely(cstr.name[0] == 0)) {
@@ -1000,8 +999,6 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
         if (res < 0)
                 goto errout;
 
-        kfree(cstr.name);
-
         paddr = pstr.name;
 
         /* Null-terminate the name */
@@ -1011,7 +1008,6 @@ static const char *f2fs_encrypted_get_link(struct dentry *dentry,
         set_delayed_call(done, kfree_link, paddr);
         return paddr;
 errout:
-        kfree(cstr.name);
         f2fs_fname_crypto_free_buffer(&pstr);
         page_cache_release(cpage);
         return ERR_PTR(res);