The patch titled
floppy: fix jiffies dependency
has been added to the -mm tree. Its filename is
floppy-fix-jiffies-dependency.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: floppy: fix jiffies dependency
From: Sylvain Ferriol <sferriol@xxxxxxx>
=====
BUG 1
=====
bug_1 symptom:
--------------
sometimes after changing disk floppy, the mount command returns:
$ mount -t ext2 /dev/fd0 /mnt
mount: Mounting /dev/fd0 on/mnt failed: Invalid argument
and the kernel floppy driver log is:
kernel: floppy0: disk absent or changed during operation
bug_1 description:
------------------
last_checked is the date (in jiffies) of the last disk check
the mount process calls floppy_open which :
- set last_checked to 0
- calls check_floppy_change
check_floppy_change checks disk only when last_checked + checkfreq >
current_time(jiffies)
it uses time_after jiffies macro: if(time_after(jiffies, (last_checked+checkfreq))
but by setting last_checked to an absolute value (0) in floppy_open, check disk
is done depending on the value of current time.
and if jiffies = 0xffffffff, there is no check and the mount fails
bug_1 solution:
---------------
a better way to force disk check in floppy_open is to set last_checked = jiffies
- checkfreq - 1
=====
BUG 2
=====
bug_2 symptom:
--------------
if we activate debug (modprobe floppy floppy=debug), bug_1 does not appear.
bug_2 decription:
-----------------
debug activates the following print:
DPRINT("disk change line=%x\n", fd_inb(FD_DIR) & 0x80);
as fd_inb returns that floppy has changed, the next call:
if ((fd_inb(FD_DIR) ^ UDP->flags) & 0x80) {
returns always false
and it never detects if floppy has changed during operation => bug1 not detected
bug 2 solution:
---------------
char dir = 0; /* digital input register */
/* MUST be called only once for checking disk change */
dir = fd_inb(FD_DIR);
DPRINT("disk change line=%x\n", dir & 0x80);
if ((dir ^ UDP->flags) & 0x80) {
Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
---
drivers/block/floppy.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff -puN drivers/block/floppy.c~floppy-fix-jiffies-dependency drivers/block/floppy.c
--- a/drivers/block/floppy.c~floppy-fix-jiffies-dependency
+++ a/drivers/block/floppy.c
@@ -733,6 +733,8 @@ static void reschedule_timeout(int drive
static int disk_change(int drive)
{
int fdc = FDC(drive);
+ char dir = 0; /* digital input register */
+
#ifdef FLOPPY_SANITY_CHECK
if (time_before(jiffies, UDRS->select_date + UDP->select_delay))
DPRINT("WARNING disk change called early\n");
@@ -744,17 +746,20 @@ static int disk_change(int drive)
}
#endif
+ /* MUST be called only once for checking disk change */
+ dir = fd_inb(FD_DIR);
+
#ifdef DCL_DEBUG
if (UDP->flags & FD_DEBUG) {
DPRINT("checking disk change line for drive %d\n", drive);
DPRINT("jiffies=%lu\n", jiffies);
- DPRINT("disk change line=%x\n", fd_inb(FD_DIR) & 0x80);
+ DPRINT("disk change line=%x\n", dir & 0x80);
DPRINT("flags=%lx\n", UDRS->flags);
}
#endif
if (UDP->flags & FD_BROKEN_DCL)
return UTESTF(FD_DISK_CHANGED);
- if ((fd_inb(FD_DIR) ^ UDP->flags) & 0x80) {
+ if ((dir ^ UDP->flags) & 0x80) {
USETF(FD_VERIFY); /* verify write protection */
if (UDRS->maxblock) {
/* mark it changed */
@@ -3762,7 +3767,9 @@ static int floppy_open(struct inode *ino
if (!(filp->f_flags & O_NDELAY)) {
if (filp->f_mode & 3) {
- UDRS->last_checked = 0;
+ /* Force check disk by putting the date of the last check
+ * far enough in the past */
+ UDRS->last_checked = jiffies - UDP->checkfreq - 1;
check_disk_change(inode->i_bdev);
if (UTESTF(FD_DISK_CHANGED))
goto out;
_
Patches currently in -mm which might be from sferriol@xxxxxxx are
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