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Date: Mon, 1 Jul 2013 19:40:28 +0800
From: bintian.wang@...aro.org
To: linux-kernel@...r.kernel.org
Cc: Mike Lockwood <lockwood@...roid.com>,
dmitry pervushin <dpervushin@...il.com>,
Colin Cross <ccross@...roid.com>,
Android Kernel Team <kernel-team@...roid.com>,
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>,
Andrew Morton <akpm@...ux-foundation.org>,
John Stultz <john.stultz@...aro.org>,
Bintian Wang <bintian.wang@...aro.org>
Subject: [PATCH RFC] Add FAT_IOCTL_GET_VOLUME_ID
From: Mike Lockwood <lockwood@...roid.com>
Adds vfat ioctl command FAT_IOCTL_GET_VOLUME_ID, with this command
we can get the vfat volume ID using following code:
ioctl(fd, FAT_IOCTL_GET_VOLUME_ID, &volume_ID)
This patch is a modified version of the android kernel patch by Mike Lockwood,
the original patch makes the return value of ioctl() as the volume ID,
Dmitry Pervushin noticed some volume IDs abiguous with error returns:
for example, if volume id is set to "0xFFFFFDAD", that matches -ENOIOCTLCMD,
we get a wrong volume ID "0xFFFFFFFF" from the user space.
This patch fixes above bug by adding a parameter to ioctl to get the correct
volume ID.
Cc: dmitry pervushin <dpervushin@...il.com>
Cc: Mike Lockwood <lockwood@...roid.com>
Cc: Colin Cross <ccross@...roid.com>
Cc: Android Kernel Team <kernel-team@...roid.com>
Cc: OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: John Stultz <john.stultz@...aro.org>
Signed-off-by: Bintian Wang <bintian.wang@...aro.org>
---
fs/fat/fat.h | 1 +
fs/fat/file.c | 8 ++++++++
fs/fat/inode.c | 12 ++++++++++++
include/uapi/linux/msdos_fs.h | 10 ++++++++++
4 files changed, 31 insertions(+)
diff --git a/fs/fat/fat.h b/fs/fat/fat.h
index 21664fc..4241e6f 100644
--- a/fs/fat/fat.h
+++ b/fs/fat/fat.h
@@ -86,6 +86,7 @@ struct msdos_sb_info {
const void *dir_ops; /* Opaque; default directory operations */
int dir_per_block; /* dir entries per block */
int dir_per_block_bits; /* log2(dir_per_block) */
+ unsigned int vol_id; /*volume ID*/
int fatent_shift;
struct fatent_operations *fatent_ops;
diff --git a/fs/fat/file.c b/fs/fat/file.c
index b0b632e..ceef10e 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -114,6 +114,12 @@ out:
return err;
}
+static unsigned int fat_ioctl_volume_id(struct inode *inode)
+{
+ struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb);
+ return sbi->vol_id;
+}
+
long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
struct inode *inode = file_inode(filp);
@@ -124,6 +130,8 @@ long fat_generic_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
return fat_ioctl_get_attributes(inode, user_attr);
case FAT_IOCTL_SET_ATTRIBUTES:
return fat_ioctl_set_attributes(filp, user_attr);
+ case FAT_IOCTL_GET_VOLUME_ID:
+ return put_user(fat_ioctl_volume_id(inode), user_attr);
default:
return -ENOTTY; /* Inappropriate ioctl for device */
}
diff --git a/fs/fat/inode.c b/fs/fat/inode.c
index 5d4513c..11b51bb 100644
--- a/fs/fat/inode.c
+++ b/fs/fat/inode.c
@@ -1415,6 +1415,18 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat,
brelse(fsinfo_bh);
}
+ /* interpret volume ID as a little endian 32 bit integer */
+ if (sbi->fat_bits == 32)
+ sbi->vol_id = (((u32)b->fat32.vol_id[0]) |
+ ((u32)b->fat32.vol_id[1] << 8) |
+ ((u32)b->fat32.vol_id[2] << 16) |
+ ((u32)b->fat32.vol_id[3] << 24));
+ else /* fat 16 or 12 */
+ sbi->vol_id = (((u32)b->fat16.vol_id[0]) |
+ ((u32)b->fat16.vol_id[1] << 8) |
+ ((u32)b->fat16.vol_id[2] << 16) |
+ ((u32)b->fat16.vol_id[3] << 24));
+
sbi->dir_per_block = sb->s_blocksize / sizeof(struct msdos_dir_entry);
sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
diff --git a/include/uapi/linux/msdos_fs.h b/include/uapi/linux/msdos_fs.h
index f055e58..e284ff9 100644
--- a/include/uapi/linux/msdos_fs.h
+++ b/include/uapi/linux/msdos_fs.h
@@ -104,6 +104,8 @@ struct __fat_dirent {
/* <linux/videotext.h> has used 0x72 ('r') in collision, so skip a few */
#define FAT_IOCTL_GET_ATTRIBUTES _IOR('r', 0x10, __u32)
#define FAT_IOCTL_SET_ATTRIBUTES _IOW('r', 0x11, __u32)
+/*Android kernel has used 0x12, so we use 0x13*/
+#define FAT_IOCTL_GET_VOLUME_ID _IOR('r', 0x13, __u32)
struct fat_boot_sector {
__u8 ignored[3]; /* Boot strap short or near jump */
@@ -128,6 +130,10 @@ struct fat_boot_sector {
__u8 drive_number; /* Physical drive number */
__u8 state; /* undocumented, but used
for mount state. */
+ __u8 signature; /* extended boot signature */
+ __u8 vol_id[4]; /* volume ID */
+ __u8 vol_label[11]; /* volume label */
+ __u8 fs_type[8]; /* file system type */
/* other fiealds are not added here */
} fat16;
@@ -147,6 +153,10 @@ struct fat_boot_sector {
__u8 drive_number; /* Physical drive number */
__u8 state; /* undocumented, but used
for mount state. */
+ __u8 signature; /* extended boot signature */
+ __u8 vol_id[4]; /* volume ID */
+ __u8 vol_label[11]; /* volume label */
+ __u8 fs_type[8]; /* file system type */
/* other fiealds are not added here */
} fat32;
};
--
1.7.9.5
--
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