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Date: Tue, 3 Jul 2018 13:06:58 -0400
From: Gabriel Krisman Bertazi <krisman@...labora.co.uk>
To: tytso@....edu
Cc: linux-ext4@...r.kernel.org, darrick.wong@...cle.com,
kernel@...labora.com,
Gabriel Krisman Bertazi <krisman@...labora.co.uk>
Subject: [PATCH 18/20] ext4: Support encoding-aware file name lookups
Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.co.uk>
---
fs/ext4/namei.c | 60 +++++++++++++++++++++++++++++++++++++++++++++----
1 file changed, 56 insertions(+), 4 deletions(-)
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index 2a4c25c4681d..e4906bac7279 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -35,6 +35,7 @@
#include <linux/buffer_head.h>
#include <linux/bio.h>
#include <linux/iversion.h>
+#include <linux/nls.h>
#include "ext4.h"
#include "ext4_jbd2.h"
@@ -1251,15 +1252,26 @@ static void dx_insert_block(struct dx_frame *frame, u32 hash, ext4_lblk_t block)
dx_set_count(entries, count + 1);
}
+static inline bool ext4_charset_match_name(struct nls_table *charset,
+ const struct fscrypt_name *fname,
+ const u8 *de_name,
+ u32 de_name_len)
+{
+ return !nls_strncmp(charset, (char *) de_name, de_name_len,
+ fname->disk_name.name, fname->disk_name.len);
+}
+
/*
* Test whether a directory entry matches the filename being searched for.
*
* Return: %true if the directory entry matches, otherwise %false.
*/
-static inline bool ext4_match(const struct ext4_filename *fname,
+static inline bool ext4_match(const struct inode *parent,
+ const struct ext4_filename *fname,
const struct ext4_dir_entry_2 *de)
{
struct fscrypt_name f;
+ const struct ext4_sb_info *sbi = EXT4_SB(parent->i_sb);
if (!de->inode)
return false;
@@ -1269,6 +1281,11 @@ static inline bool ext4_match(const struct ext4_filename *fname,
#ifdef CONFIG_EXT4_FS_ENCRYPTION
f.crypto_buf = fname->crypto_buf;
#endif
+
+ if (sbi->encoding)
+ return ext4_charset_match_name(sbi->encoding, &f,
+ de->name, de->name_len);
+
return fscrypt_match_name(&f, de->name, de->name_len);
}
@@ -1289,7 +1306,7 @@ int ext4_search_dir(struct buffer_head *bh, char *search_buf, int buf_size,
/* this code is executed quadratically often */
/* do minimal checking `by hand' */
if ((char *) de + de->name_len <= dlimit &&
- ext4_match(fname, de)) {
+ ext4_match(dir, fname, de)) {
/* found a match - just to be sure, do
* a full check */
if (ext4_check_dir_entry(dir, NULL, de, bh, bh->b_data,
@@ -1345,6 +1362,7 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
struct buffer_head *bh_use[NAMEI_RA_SIZE];
struct buffer_head *bh, *ret = NULL;
ext4_lblk_t start, block;
+ struct ext4_sb_info *sbi = EXT4_SB(dir->i_sb);
const u8 *name = d_name->name;
size_t ra_max = 0; /* Number of bh's in the readahead
buffer, bh_use[] */
@@ -1393,9 +1411,16 @@ static struct buffer_head * ext4_find_entry (struct inode *dir,
* On success, or if the error was file not found,
* return. Otherwise, fall back to doing a search the
* old fashioned way.
+ *
+ * Even if we are doing encodings, an exact-match lookup
+ * could still benefit from DX, so we don't skip it
+ * entirely. Only if it fails to find a match, we
+ * fallback to linear search.
*/
- if (!IS_ERR(ret) || PTR_ERR(ret) != ERR_BAD_DX_DIR)
+ if ((ret && (!IS_ERR(ret) || PTR_ERR(ret) != ERR_BAD_DX_DIR))
+ || (!ret && !sbi->encoding))
goto cleanup_and_exit;
+
dxtrace(printk(KERN_DEBUG "ext4_find_entry: dx failed, "
"falling back\n"));
}
@@ -1544,6 +1569,7 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi
struct inode *inode;
struct ext4_dir_entry_2 *de;
struct buffer_head *bh;
+ struct ext4_sb_info *sbi = EXT4_SB(dir->i_sb);
int err;
err = fscrypt_prepare_lookup(dir, dentry, flags);
@@ -1585,6 +1611,32 @@ static struct dentry *ext4_lookup(struct inode *dir, struct dentry *dentry, unsi
iput(inode);
return ERR_PTR(-EPERM);
}
+
+ if (sbi->encoding) {
+ struct dentry *new;
+ struct qstr ciname;
+ char *name;
+
+ name = kmalloc((sizeof(char) * de->name_len) + 1,
+ GFP_NOFS);
+ if (!name)
+ return ERR_PTR(-ENOMEM);
+
+ memcpy(name, de->name, de->name_len);
+ name[de->name_len] = '\0';
+ ciname.len = de->name_len;
+ ciname.name = name;
+ new = d_add_ci(dentry, inode, &ciname);
+ kfree(name);
+ return new;
+ }
+ } else if (sbi->encoding) {
+ /* Eventually we want to call d_add_ci(dentry, NULL) for
+ * negative dentries in the encoding case as well. For
+ * now, prevent the negative dentry from being
+ * cached.
+ */
+ return NULL;
}
return d_splice_alias(inode, dentry);
}
@@ -1796,7 +1848,7 @@ int ext4_find_dest_de(struct inode *dir, struct inode *inode,
if (ext4_check_dir_entry(dir, NULL, de, bh,
buf, buf_size, offset))
return -EFSCORRUPTED;
- if (ext4_match(fname, de))
+ if (ext4_match(dir, fname, de))
return -EEXIST;
nlen = EXT4_DIR_REC_LEN(de->name_len);
rlen = ext4_rec_len_from_disk(de->rec_len, buf_size);
--
2.18.0
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