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Commit 6e29e14f authored by Daniel Rosenberg's avatar Daniel Rosenberg
Browse files

FROMLIST: Add standard casefolding support 



This adds general supporting functions for filesystems that use
utf8 casefolding. It provides standard dentry_operations and adds the
necessary structures in struct super_block to allow this standardization.

Ext4 and F2fs are switch to these implementations.

Signed-off-by: default avatarDaniel Rosenberg <drosen@google.com>
Note: Fixed issue with non-strictly enforced fallback hash
Test: Boots, /data/media is case insensitive
Bug: 138322712
Link: https://lore.kernel.org/linux-f2fs-devel/20200208013552.241832-1-drosen@google.com/T/#t
Change-Id: I81b5fb5d3ce0259a60712ae2505c1e4b03dbafde
parent 73f57a09

fs/libfs.c

+61 −0
Original line number Diff line number Diff line
@@ -16,6 +16,8 @@ 
#include <linux/exportfs.h>

#include <linux/writeback.h>

#include <linux/buffer_head.h> /* sync_mapping_buffers */

#include <linux/unicode.h>

#include <linux/fscrypt.h>



#include <linux/uaccess.h>
@@ -1258,3 +1260,62 @@ bool is_empty_dir_inode(struct inode *inode) 
	return (inode->i_fop == &empty_dir_operations) &&

		(inode->i_op == &empty_dir_inode_operations);

}



#ifdef CONFIG_UNICODE

bool needs_casefold(const struct inode *dir)

{

	return IS_CASEFOLDED(dir) && dir->i_sb->s_encoding &&

			(!IS_ENCRYPTED(dir) || fscrypt_has_encryption_key(dir));

}

EXPORT_SYMBOL(needs_casefold);



int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,

			  const char *str, const struct qstr *name)

{

	const struct dentry *parent = READ_ONCE(dentry->d_parent);

	const struct inode *inode = READ_ONCE(parent->d_inode);

	const struct super_block *sb = dentry->d_sb;

	const struct unicode_map *um = sb->s_encoding;

	struct qstr entry = QSTR_INIT(str, len);

	int ret;



	if (!inode || !needs_casefold(inode))

		goto fallback;



	ret = utf8_strncasecmp(um, name, &entry);

	if (ret >= 0)

		return ret;



	if (sb_has_enc_strict_mode(sb))

		return -EINVAL;

fallback:

	if (len != name->len)

		return 1;

	return !!memcmp(str, name->name, len);

}

EXPORT_SYMBOL(generic_ci_d_compare);



int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str)

{

	const struct inode *inode = READ_ONCE(dentry->d_inode);

	struct super_block *sb = dentry->d_sb;

	const struct unicode_map *um = sb->s_encoding;

	int ret = 0;



	if (!inode || !needs_casefold(inode))

		return 0;



	ret = utf8_casefold_hash(um, dentry, str);

	if (ret < 0)

		goto err;



	return 0;

err:

	if (sb_has_enc_strict_mode(sb))

		ret = -EINVAL;

	else

		ret = 0;

	return ret;

}

EXPORT_SYMBOL(generic_ci_d_hash);

#endif

include/linux/fs.h

+22 −0
Original line number Diff line number Diff line
@@ -1333,6 +1333,12 @@ extern int send_sigurg(struct fown_struct *fown); 
#define SB_ACTIVE	(1<<30)

#define SB_NOUSER	(1<<31)



/* These flags relate to encoding and casefolding */

#define SB_ENC_STRICT_MODE_FL	(1 << 0)



#define sb_has_enc_strict_mode(sb) \

	(sb->s_encoding_flags & SB_ENC_STRICT_MODE_FL)



/*

 *	Umount options

 */
@@ -1400,6 +1406,10 @@ struct super_block { 
#endif

#ifdef CONFIG_FS_VERITY

	const struct fsverity_operations *s_vop;

#endif

#ifdef CONFIG_UNICODE

	struct unicode_map *s_encoding;

	__u16 s_encoding_flags;

#endif

	struct hlist_bl_head	s_roots;	/* alternate root dentries for NFS */

	struct list_head	s_mounts;	/* list of mounts; _not_ for fs use */
@@ -3261,6 +3271,18 @@ extern int generic_file_fsync(struct file *, loff_t, loff_t, int); 


extern int generic_check_addressable(unsigned, u64);



#ifdef CONFIG_UNICODE

extern int generic_ci_d_hash(const struct dentry *dentry, struct qstr *str);

extern int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,

				const char *str, const struct qstr *name);

extern bool needs_casefold(const struct inode *dir);

#else

static inline bool needs_casefold(const struct inode *dir)

{

	return 0;

}

#endif



#ifdef CONFIG_MIGRATION

extern int buffer_migrate_page(struct address_space *,

				struct page *, struct page *,