* [PATCH 1/2] exfat: add keeptail mount option
2021-08-18 11:11 [PATCH 0/2] exfat: allow access to paths with trailing dots David Disseldorp
@ 2021-08-18 11:11 ` David Disseldorp
2021-08-18 11:11 ` [PATCH 2/2] exfat: keep trailing dots in paths if keeptail is set David Disseldorp
2021-08-18 12:48 ` [PATCH 0/2] exfat: allow access to paths with trailing dots Christian Brauner
2 siblings, 0 replies; 6+ messages in thread
From: David Disseldorp @ 2021-08-18 11:11 UTC (permalink / raw)
To: linux-fsdevel; +Cc: David Disseldorp, Takashi Iwai
The "keeptail" mount option will, in a subsequent commit, control
whether or not trailing periods '.' are stripped from path components.
Suggested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: David Disseldorp <ddiss@suse.de>
---
fs/exfat/exfat_fs.h | 3 ++-
fs/exfat/super.c | 7 +++++++
2 files changed, 9 insertions(+), 1 deletion(-)
diff --git a/fs/exfat/exfat_fs.h b/fs/exfat/exfat_fs.h
index 1d6da61157c9..af33f867b34e 100644
--- a/fs/exfat/exfat_fs.h
+++ b/fs/exfat/exfat_fs.h
@@ -204,7 +204,8 @@ struct exfat_mount_options {
/* on error: continue, panic, remount-ro */
enum exfat_error_mode errors;
unsigned utf8:1, /* Use of UTF-8 character set */
- discard:1; /* Issue discard requests on deletions */
+ discard:1, /* Issue discard requests on deletions */
+ keeptail:1; /* Keep trailing periods in paths */
int time_offset; /* Offset of timestamps from UTC (in minutes) */
};
diff --git a/fs/exfat/super.c b/fs/exfat/super.c
index 5539ffc20d16..a55c810ffd90 100644
--- a/fs/exfat/super.c
+++ b/fs/exfat/super.c
@@ -173,6 +173,8 @@ static int exfat_show_options(struct seq_file *m, struct dentry *root)
seq_puts(m, ",errors=remount-ro");
if (opts->discard)
seq_puts(m, ",discard");
+ if (opts->keeptail)
+ seq_puts(m, ",keeptail");
if (opts->time_offset)
seq_printf(m, ",time_offset=%d", opts->time_offset);
return 0;
@@ -216,6 +218,7 @@ enum {
Opt_charset,
Opt_errors,
Opt_discard,
+ Opt_keeptail,
Opt_time_offset,
/* Deprecated options */
@@ -242,6 +245,7 @@ static const struct fs_parameter_spec exfat_parameters[] = {
fsparam_string("iocharset", Opt_charset),
fsparam_enum("errors", Opt_errors, exfat_param_enums),
fsparam_flag("discard", Opt_discard),
+ fsparam_flag("keeptail", Opt_keeptail),
fsparam_s32("time_offset", Opt_time_offset),
__fsparam(NULL, "utf8", Opt_utf8, fs_param_deprecated,
NULL),
@@ -296,6 +300,9 @@ static int exfat_parse_param(struct fs_context *fc, struct fs_parameter *param)
case Opt_discard:
opts->discard = 1;
break;
+ case Opt_keeptail:
+ opts->keeptail = 1;
+ break;
case Opt_time_offset:
/*
* Make the limit 24 just in case someone invents something
--
2.31.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 2/2] exfat: keep trailing dots in paths if keeptail is set
2021-08-18 11:11 [PATCH 0/2] exfat: allow access to paths with trailing dots David Disseldorp
2021-08-18 11:11 ` [PATCH 1/2] exfat: add keeptail mount option David Disseldorp
@ 2021-08-18 11:11 ` David Disseldorp
2021-08-18 12:48 ` [PATCH 0/2] exfat: allow access to paths with trailing dots Christian Brauner
2 siblings, 0 replies; 6+ messages in thread
From: David Disseldorp @ 2021-08-18 11:11 UTC (permalink / raw)
To: linux-fsdevel; +Cc: David Disseldorp, Takashi Iwai
exfat currently unconditionally strips trailing periods '.' when
performing path lookup. This is done intentionally, loosely following
Windows behaviour and specifications which state:
#exFAT
The concatenated file name has the same set of illegal characters as
other FAT-based file systems (see Table 31).
#FAT
...
Leading and trailing spaces in a long name are ignored.
Leading and embedded periods are allowed in a name and are stored in
the long name. Trailing periods are ignored.
Note: Leading and trailing space ' ' characters are currently retained
by Linux kernel exfat, in conflict with the above specification.
Some implementations, such as fuse-exfat, don't perform path trailer
removal. When mounting images which contain trailing-dot paths, these
paths are unreachable, e.g.:
+ mount.exfat-fuse /dev/zram0 /mnt/test/
FUSE exfat 1.3.0
+ cd /mnt/test/
+ touch fuse_created_dots... ' fuse_created_spaces '
+ ls -l
total 0
-rwxrwxrwx 1 root 0 0 Aug 18 09:45 ' fuse_created_spaces '
-rwxrwxrwx 1 root 0 0 Aug 18 09:45 fuse_created_dots...
+ cd /
+ umount /mnt/test/
+ mount -t exfat /dev/zram0 /mnt/test
+ cd /mnt/test
+ ls -l
ls: cannot access 'fuse_created_dots...': No such file or directory
total 0
-rwxr-xr-x 1 root 0 0 Aug 18 09:45 ' fuse_created_spaces '
-????????? ? ? ? ? ? fuse_created_dots...
+ touch kexfat_created_dots... ' kexfat_created_spaces '
+ ls -l
ls: cannot access 'fuse_created_dots...': No such file or directory
total 0
-rwxr-xr-x 1 root 0 0 Aug 18 09:45 ' fuse_created_spaces '
-rwxr-xr-x 1 root 0 0 Aug 18 09:45 ' kexfat_created_spaces '
-????????? ? ? ? ? ? fuse_created_dots...
-rwxr-xr-x 1 root 0 0 Aug 18 09:45 kexfat_created_dots
+ cd /
+ umount /mnt/test/
With this change, the "keeptail" mount option can be used to access
paths with trailing periods. E.g. continuing from the previous example:
+ mount -t exfat -o keeptail /dev/zram0 /mnt/test
+ cd /mnt/test
+ ls -l
total 0
-rwxr-xr-x 1 root 0 0 Aug 18 10:32 ' fuse_created_spaces '
-rwxr-xr-x 1 root 0 0 Aug 18 10:32 ' kexfat_created_spaces '
-rwxr-xr-x 1 root 0 0 Aug 18 10:32 fuse_created_dots...
-rwxr-xr-x 1 root 0 0 Aug 18 10:32 kexfat_created_dots
Link: https://bugzilla.suse.com/show_bug.cgi?id=1188964
Link: https://lore.kernel.org/linux-fsdevel/003b01d755e4$31fb0d80$95f12880$@samsung.com/
Link: https://docs.microsoft.com/en-us/windows/win32/fileio/exfat-specification#773-filename-field
Suggested-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: David Disseldorp <ddiss@suse.de>
---
fs/exfat/namei.c | 25 ++++++++++++++-----------
1 file changed, 14 insertions(+), 11 deletions(-)
diff --git a/fs/exfat/namei.c b/fs/exfat/namei.c
index 24b41103d1cc..e49455ce6da2 100644
--- a/fs/exfat/namei.c
+++ b/fs/exfat/namei.c
@@ -65,11 +65,14 @@ static int exfat_d_revalidate(struct dentry *dentry, unsigned int flags)
return ret;
}
-/* returns the length of a struct qstr, ignoring trailing dots */
-static unsigned int exfat_striptail_len(unsigned int len, const char *name)
+/* returns the length of a struct qstr, possibly ignoring trailing dots */
+static unsigned int exfat_striptail_len(struct super_block *sb,
+ unsigned int len, const char *name)
{
- while (len && name[len - 1] == '.')
- len--;
+ if (!EXFAT_SB(sb)->options.keeptail) {
+ while (len && name[len - 1] == '.')
+ len--;
+ }
return len;
}
@@ -83,7 +86,7 @@ static int exfat_d_hash(const struct dentry *dentry, struct qstr *qstr)
struct super_block *sb = dentry->d_sb;
struct nls_table *t = EXFAT_SB(sb)->nls_io;
const unsigned char *name = qstr->name;
- unsigned int len = exfat_striptail_len(qstr->len, qstr->name);
+ unsigned int len = exfat_striptail_len(sb, qstr->len, qstr->name);
unsigned long hash = init_name_hash(dentry);
int i, charlen;
wchar_t c;
@@ -104,8 +107,8 @@ static int exfat_d_cmp(const struct dentry *dentry, unsigned int len,
{
struct super_block *sb = dentry->d_sb;
struct nls_table *t = EXFAT_SB(sb)->nls_io;
- unsigned int alen = exfat_striptail_len(name->len, name->name);
- unsigned int blen = exfat_striptail_len(len, str);
+ unsigned int alen = exfat_striptail_len(sb, name->len, name->name);
+ unsigned int blen = exfat_striptail_len(sb, len, str);
wchar_t c1, c2;
int charlen, i;
@@ -136,7 +139,7 @@ static int exfat_utf8_d_hash(const struct dentry *dentry, struct qstr *qstr)
{
struct super_block *sb = dentry->d_sb;
const unsigned char *name = qstr->name;
- unsigned int len = exfat_striptail_len(qstr->len, qstr->name);
+ unsigned int len = exfat_striptail_len(sb, qstr->len, qstr->name);
unsigned long hash = init_name_hash(dentry);
int i, charlen;
unicode_t u;
@@ -161,8 +164,8 @@ static int exfat_utf8_d_cmp(const struct dentry *dentry, unsigned int len,
const char *str, const struct qstr *name)
{
struct super_block *sb = dentry->d_sb;
- unsigned int alen = exfat_striptail_len(name->len, name->name);
- unsigned int blen = exfat_striptail_len(len, str);
+ unsigned int alen = exfat_striptail_len(sb, name->len, name->name);
+ unsigned int blen = exfat_striptail_len(sb, len, str);
unicode_t u_a, u_b;
int charlen, i;
@@ -419,7 +422,7 @@ static int __exfat_resolve_path(struct inode *inode, const unsigned char *path,
struct exfat_inode_info *ei = EXFAT_I(inode);
/* strip all trailing periods */
- namelen = exfat_striptail_len(strlen(path), path);
+ namelen = exfat_striptail_len(sb, strlen(path), path);
if (!namelen)
return -ENOENT;
--
2.31.1
^ permalink raw reply related [flat|nested] 6+ messages in thread