The comment edited in this patch was the only reference to the FAT_FIRST_ENT macro, which is not used anymore. Moreover, the commented line of code does not compile with the current code.
Since the FAT_FIRST_ENT macro checks the FAT variant in a way that the patch series changes, I removed it, and instead wrote a clear explanation of what was checked. I verified that the changed comment is correct according to Microsoft FAT spec, search for "BPB_Media" in the following references: 1. Microsoft FAT specification 2005 (http://read.pudn.com/downloads77/ebook/294884/FAT32%20Spec%20%28SDA%20Contribution%29.pdf). Search for 'volume label'. 2. Microsoft Extensible Firmware Initiative, FAT32 File System Specification (https://staff.washington.edu/dittrich/misc/fatgen103.pdf). Search for 'volume label'. Signed-off-by: Carmeli Tamir <carmeli.ta...@gmail.com> --- fs/fat/inode.c | 12 ++++++++---- include/uapi/linux/msdos_fs.h | 3 --- 2 files changed, 8 insertions(+), 7 deletions(-) diff --git a/fs/fat/inode.c b/fs/fat/inode.c index e981e9d..708de6d 100644 --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -1804,11 +1804,15 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat, fat_ent_access_init(sb); /* - * The low byte of FAT's first entry must have same value with - * media-field. But in real world, too many devices is - * writing wrong value. So, removed that validity check. + * The low byte of the first FAT entry must have the same value as + * the media field of the boot sector. But in real world, too many + * devices are writing wrong values. So, removed that validity check. * - * if (FAT_FIRST_ENT(sb, media) != first) + * The removed check compared the first FAT entry to a value dependent + * on the media field like this: + * == (0x0F00 | media), for FAT12 + * == (0XFF00 | media), for FAT16 + * == (0x0FFFFF | media), for FAT32 */ error = -EINVAL; diff --git a/include/uapi/linux/msdos_fs.h b/include/uapi/linux/msdos_fs.h index 1216e6c..833c707 100644 --- a/include/uapi/linux/msdos_fs.h +++ b/include/uapi/linux/msdos_fs.h @@ -58,9 +58,6 @@ #define MSDOS_DOT ". " /* ".", padded to MSDOS_NAME chars */ #define MSDOS_DOTDOT ".. " /* "..", padded to MSDOS_NAME chars */ -#define FAT_FIRST_ENT(s, x) ((MSDOS_SB(s)->fat_bits == 32 ? 0x0FFFFF00 : \ - MSDOS_SB(s)->fat_bits == 16 ? 0xFF00 : 0xF00) | (x)) - /* start of data cluster's entry (number of reserved clusters) */ #define FAT_START_ENT 2 -- 2.7.4
