diff options
| author | Mike Lockwood <lockwood@android.com> | 2013-07-08 16:00:46 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-07-09 10:33:25 -0700 |
| commit | 6e5b93ee55d401f1619092fb675b57c28c9ed7ec (patch) | |
| tree | d6d9627ec023d7375d8dc996523509ee45d082bd /fs/fat/inode.c | |
| parent | 4e80b1880c5a31d051d1e4a7377dec0a20701c23 (diff) | |
fatfs: add FAT_IOCTL_GET_VOLUME_ID
This patch, originally from Android kernel, 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 patch by Mike Lockwood, with
changes from Dmitry Pervushin, who noticed the original patch makes some
volume IDs abiguous with error returns: for example, if volume id is
0xFFFFFDAD, that matches -ENOIOCTLCMD, we get "FFFFFFFF" from the user
space.
So add a parameter to ioctl to get the correct volume ID.
Android uses vfat volume ID to identify different sd card, when a new sd
card is inserted to device, android can scan the media on it and pop up
new contents.
Signed-off-by: Bintian Wang <bintian.wang@linaro.org>
Cc: dmitry pervushin <dpervushin@gmail.com>
Cc: Mike Lockwood <lockwood@android.com>
Cc: Colin Cross <ccross@android.com>
Acked-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Sean McNeil <sean@mcneil.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/fat/inode.c')
| -rw-r--r-- | fs/fat/inode.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 5d4513cb1b3..11b51bb55b4 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; |