* [PATCH] Reread partition table when a partition is added
@ 2004-08-22 22:19 Stefanos Harhalakis
2004-08-23 9:53 ` Andries Brouwer
0 siblings, 1 reply; 3+ messages in thread
From: Stefanos Harhalakis @ 2004-08-22 22:19 UTC (permalink / raw)
To: rmk; +Cc: linux-kernel
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This small patch rereads the partition table even if the block device is
beeing used. It only rereads it when there are no changes at the current
partitions and there are new partitions added at the end. Any existing
partition change will/should make it fail.
Is it OK and/or useful ?
(I'm quite inexperienced about kernel coding so be gentle :)
Signed-off-by: Stefanos Harhalakis <v13@priest.com>
RCS file: /usr/local/cvsroot/linux-2.6/fs/partitions/check.c,v
retrieving revision 1.1.1.1
diff -u -p -r1.1.1.1 check.c
--- check.c 22 Aug 2004 11:08:27 -0000 1.1.1.1
+++ check.c 22 Aug 2004 22:09:11 -0000
@@ -391,19 +391,44 @@ void register_disk(struct gendisk *disk)
blkdev_put(bdev);
}
+/*
+ * Determine the last partition.
+ * Return the partition number or 0 if there is no partition
+ */
+static int get_last_partition(struct gendisk *disk)
+{
+ int n, ret = 0;
+
+ for (n=0; n < disk->minors ; n++) {
+ if (disk->part[n])
+ ret=n+1;
+ }
+
+ return(ret);
+}
+
int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
{
struct parsed_partitions *state;
+ struct hd_struct *phd;
int p, res;
+ int is_busy = 0, last_partition = 0;
+
+ if (bdev->bd_part_count) {
+ is_busy = 1;
+ last_partition=get_last_partition(disk);
+ }
- if (bdev->bd_part_count)
- return -EBUSY;
res = invalidate_partition(disk, 0);
if (res)
return res;
bdev->bd_invalidated = 0;
- for (p = 1; p < disk->minors; p++)
- delete_partition(disk, p);
+
+ if (!is_busy) {
+ for (p = 1; p < disk->minors; p++)
+ delete_partition(disk, p);
+ }
+
if (disk->fops->revalidate_disk)
disk->fops->revalidate_disk(disk);
if (!get_capacity(disk) || !(state = check_partition(disk, bdev)))
@@ -411,13 +436,29 @@ int rescan_partitions(struct gendisk *di
for (p = 1; p < state->limit; p++) {
sector_t size = state->parts[p].size;
sector_t from = state->parts[p].from;
+
+ if (is_busy && p<=last_partition) {
+ phd=disk->part[p-1];
+ if (phd != NULL && (phd->start_sect != from ||
+ phd->nr_sects != size)) {
+ printk(KERN_INFO
+ "Existing partition was changed. "
+ "Reboot is required.\n");
+ res=-EBUSY;
+ break;
+ }
+ }
+
if (!size)
continue;
- add_partition(disk, p, from, size);
+
+ if (!is_busy || p>last_partition) {
+ add_partition(disk, p, from, size);
#ifdef CONFIG_BLK_DEV_MD
- if (state->parts[p].flags)
- md_autodetect_dev(bdev->bd_dev+p);
+ if (state->parts[p].flags)
+ md_autodetect_dev(bdev->bd_dev+p);
#endif
+ }
}
kfree(state);
return res;
[-- Attachment #1.2: rescan_partitions.patch --]
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RCS file: /usr/local/cvsroot/linux-2.6/fs/partitions/check.c,v
retrieving revision 1.1.1.1
diff -u -p -r1.1.1.1 check.c
--- check.c 22 Aug 2004 11:08:27 -0000 1.1.1.1
+++ check.c 22 Aug 2004 22:09:11 -0000
@@ -391,19 +391,44 @@ void register_disk(struct gendisk *disk)
blkdev_put(bdev);
}
+/*
+ * Determine the last partition.
+ * Return the partition number or 0 if there is no partition
+ */
+static int get_last_partition(struct gendisk *disk)
+{
+ int n, ret = 0;
+
+ for (n=0; n < disk->minors ; n++) {
+ if (disk->part[n])
+ ret=n+1;
+ }
+
+ return(ret);
+}
+
int rescan_partitions(struct gendisk *disk, struct block_device *bdev)
{
struct parsed_partitions *state;
+ struct hd_struct *phd;
int p, res;
+ int is_busy = 0, last_partition = 0;
+
+ if (bdev->bd_part_count) {
+ is_busy = 1;
+ last_partition=get_last_partition(disk);
+ }
- if (bdev->bd_part_count)
- return -EBUSY;
res = invalidate_partition(disk, 0);
if (res)
return res;
bdev->bd_invalidated = 0;
- for (p = 1; p < disk->minors; p++)
- delete_partition(disk, p);
+
+ if (!is_busy) {
+ for (p = 1; p < disk->minors; p++)
+ delete_partition(disk, p);
+ }
+
if (disk->fops->revalidate_disk)
disk->fops->revalidate_disk(disk);
if (!get_capacity(disk) || !(state = check_partition(disk, bdev)))
@@ -411,13 +436,29 @@ int rescan_partitions(struct gendisk *di
for (p = 1; p < state->limit; p++) {
sector_t size = state->parts[p].size;
sector_t from = state->parts[p].from;
+
+ if (is_busy && p<=last_partition) {
+ phd=disk->part[p-1];
+ if (phd != NULL && (phd->start_sect != from ||
+ phd->nr_sects != size)) {
+ printk(KERN_INFO
+ "Existing partition was changed. "
+ "Reboot is required.\n");
+ res=-EBUSY;
+ break;
+ }
+ }
+
if (!size)
continue;
- add_partition(disk, p, from, size);
+
+ if (!is_busy || p>last_partition) {
+ add_partition(disk, p, from, size);
#ifdef CONFIG_BLK_DEV_MD
- if (state->parts[p].flags)
- md_autodetect_dev(bdev->bd_dev+p);
+ if (state->parts[p].flags)
+ md_autodetect_dev(bdev->bd_dev+p);
#endif
+ }
}
kfree(state);
return res;
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Reread partition table when a partition is added
2004-08-22 22:19 [PATCH] Reread partition table when a partition is added Stefanos Harhalakis
@ 2004-08-23 9:53 ` Andries Brouwer
2004-08-23 16:14 ` V13
0 siblings, 1 reply; 3+ messages in thread
From: Andries Brouwer @ 2004-08-23 9:53 UTC (permalink / raw)
To: Stefanos Harhalakis; +Cc: rmk, linux-kernel
On Mon, Aug 23, 2004 at 01:19:06AM +0300, Stefanos Harhalakis wrote:
> This small patch rereads the partition table even if the block device is
> beeing used. It only rereads it when there are no changes at the current
> partitions and there are new partitions added at the end. Any existing
> partition change will/should make it fail.
>
> Is it OK and/or useful ?
What you want is possible already today.
For an example, see partx in util-linux.
Andries
[More precisely: rereading the pt consists of (i) reading pt, and
(ii) updating kernel tables. Now (i) can be done from user space,
by fdisk-type programs, and (ii) can be done from user space,
by partx-type programs.]
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] Reread partition table when a partition is added
2004-08-23 9:53 ` Andries Brouwer
@ 2004-08-23 16:14 ` V13
0 siblings, 0 replies; 3+ messages in thread
From: V13 @ 2004-08-23 16:14 UTC (permalink / raw)
To: Andries Brouwer; +Cc: rmk, linux-kernel
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On Monday 23 August 2004 12:53, Andries Brouwer wrote:
> On Mon, Aug 23, 2004 at 01:19:06AM +0300, Stefanos Harhalakis wrote:
> > This small patch rereads the partition table even if the block device
> > is beeing used. It only rereads it when there are no changes at the
> > current partitions and there are new partitions added at the end. Any
> > existing partition change will/should make it fail.
> >
> > Is it OK and/or useful ?
>
> What you want is possible already today.
> For an example, see partx in util-linux.
Oh! didn't new about that. Indeed it seems to be the right thing to do (tm)
regarding partition handling. Util-linux does not build partx by default so I
didn't notice it at all.
Thanks!
> Andries
<<V13>>
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^ permalink raw reply [flat|nested] 3+ messages in thread
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