* [PATCH] mm: fix blkdev size calculation in generic_write_checks
@ 2007-08-15 13:52 Dmitry Monakhov
2007-09-12 3:25 ` Andrew Morton
2008-02-26 23:49 ` Andrew Morton
0 siblings, 2 replies; 4+ messages in thread
From: Dmitry Monakhov @ 2007-08-15 13:52 UTC (permalink / raw)
To: linux-kernel; +Cc: axboe
Currently block device size calculated regardless its
bd_block_size. This may result attempt to write outside
block device if i_size not aligned to bdev->bd_block_size
and result in EIO.
#### TEST_CASE_BEGIN
# fdisk -l /dev/sdc
Disk /dev/sdc: 36.7 GB, 36703918080 bytes
255 heads, 63 sectors/track, 4462 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sdc1 * 1 254 2040223+ 83 Ldinux
/dev/sdc2 255 379 1004062+ 83 Linux
####
#### /dev/sdc2 size not aligned to 4K
#### at this time bd_block_size == 512 so generic_write_check
#### performed correctly
# dd if=/dev/zero of=/dev/sdc2 bs=1k count=7 seek=1004058
dd: writing `/dev/sdc2': No space left on device
5+0 records in
4+0 records out
#### this bdev contain ext4fs with blksize = 4K
# mount /dev/sdc2 /mnt/
#### after we mounted this bdev bd_block_size == fsblksize == 4K
#### the same write operation failed with EIO
# dd if=/dev/zero of=/dev/sdc2 bs=1k count=7 seek=1004058
dd: writing `/dev/sdc2': Input/output error
3+0 records in
2+0 records out
#### Attempt to write whole fsblock result write access outside
#### blkdevice and cause -EIO (returned by blkdev_get_block)
#### TEST_CASE_END
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
mm/filemap.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/mm/filemap.c b/mm/filemap.c
index 2c8776b..a23ee8a 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1867,9 +1867,11 @@ inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, i
} else {
#ifdef CONFIG_BLOCK
loff_t isize;
+ unsigned int blksize;
if (bdev_read_only(I_BDEV(inode)))
return -EPERM;
- isize = i_size_read(inode);
+ blksize = block_size(I_BDEV(inode));
+ isize = i_size_read(inode) & ~(blksize - 1);
if (*pos >= isize) {
if (*count || *pos > isize)
return -ENOSPC;
--
1.5.2.2
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] mm: fix blkdev size calculation in generic_write_checks
2007-08-15 13:52 [PATCH] mm: fix blkdev size calculation in generic_write_checks Dmitry Monakhov
@ 2007-09-12 3:25 ` Andrew Morton
2008-02-26 23:49 ` Andrew Morton
1 sibling, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2007-09-12 3:25 UTC (permalink / raw)
To: Dmitry Monakhov; +Cc: linux-kernel, axboe
On Wed, 15 Aug 2007 17:52:28 +0400 Dmitry Monakhov <dmonakhov@openvz.org> wrote:
> Currently block device size calculated regardless its
> bd_block_size. This may result attempt to write outside
> block device if i_size not aligned to bdev->bd_block_size
> and result in EIO.
>
> #### TEST_CASE_BEGIN
> # fdisk -l /dev/sdc
> Disk /dev/sdc: 36.7 GB, 36703918080 bytes
> 255 heads, 63 sectors/track, 4462 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
>
> Device Boot Start End Blocks Id System
> /dev/sdc1 * 1 254 2040223+ 83 Ldinux
> /dev/sdc2 255 379 1004062+ 83 Linux
> ####
> #### /dev/sdc2 size not aligned to 4K
>
> #### at this time bd_block_size == 512 so generic_write_check
> #### performed correctly
> # dd if=/dev/zero of=/dev/sdc2 bs=1k count=7 seek=1004058
> dd: writing `/dev/sdc2': No space left on device
> 5+0 records in
> 4+0 records out
>
> #### this bdev contain ext4fs with blksize = 4K
> # mount /dev/sdc2 /mnt/
> #### after we mounted this bdev bd_block_size == fsblksize == 4K
>
> #### the same write operation failed with EIO
> # dd if=/dev/zero of=/dev/sdc2 bs=1k count=7 seek=1004058
> dd: writing `/dev/sdc2': Input/output error
> 3+0 records in
> 2+0 records out
> #### Attempt to write whole fsblock result write access outside
> #### blkdevice and cause -EIO (returned by blkdev_get_block)
> #### TEST_CASE_END
>
> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
> ---
> mm/filemap.c | 4 +++-
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 2c8776b..a23ee8a 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1867,9 +1867,11 @@ inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, i
> } else {
> #ifdef CONFIG_BLOCK
> loff_t isize;
> + unsigned int blksize;
> if (bdev_read_only(I_BDEV(inode)))
> return -EPERM;
> - isize = i_size_read(inode);
> + blksize = block_size(I_BDEV(inode));
> + isize = i_size_read(inode) & ~(blksize - 1);
> if (*pos >= isize) {
> if (*count || *pos > isize)
> return -ENOSPC;
Can't say I really like the idea of adding additional overhead in this
hotpath for such an odd case. Is there a faster way of doing it? Maybe
adjust i_size, perhaps when the blocksize gets changed?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] mm: fix blkdev size calculation in generic_write_checks
2007-08-15 13:52 [PATCH] mm: fix blkdev size calculation in generic_write_checks Dmitry Monakhov
2007-09-12 3:25 ` Andrew Morton
@ 2008-02-26 23:49 ` Andrew Morton
2008-02-27 10:13 ` Dmitri Monakhov
1 sibling, 1 reply; 4+ messages in thread
From: Andrew Morton @ 2008-02-26 23:49 UTC (permalink / raw)
To: Dmitry Monakhov; +Cc: linux-kernel, axboe
On Wed, 15 Aug 2007 17:52:28 +0400 Dmitry Monakhov <dmonakhov@openvz.org> wrote:
> Currently block device size calculated regardless its
> bd_block_size. This may result attempt to write outside
> block device if i_size not aligned to bdev->bd_block_size
> and result in EIO.
>
> #### TEST_CASE_BEGIN
> # fdisk -l /dev/sdc
> Disk /dev/sdc: 36.7 GB, 36703918080 bytes
> 255 heads, 63 sectors/track, 4462 cylinders
> Units = cylinders of 16065 * 512 = 8225280 bytes
>
> Device Boot Start End Blocks Id System
> /dev/sdc1 * 1 254 2040223+ 83 Ldinux
> /dev/sdc2 255 379 1004062+ 83 Linux
> ####
> #### /dev/sdc2 size not aligned to 4K
>
> #### at this time bd_block_size == 512 so generic_write_check
> #### performed correctly
> # dd if=/dev/zero of=/dev/sdc2 bs=1k count=7 seek=1004058
> dd: writing `/dev/sdc2': No space left on device
> 5+0 records in
> 4+0 records out
>
> #### this bdev contain ext4fs with blksize = 4K
> # mount /dev/sdc2 /mnt/
> #### after we mounted this bdev bd_block_size == fsblksize == 4K
>
> #### the same write operation failed with EIO
> # dd if=/dev/zero of=/dev/sdc2 bs=1k count=7 seek=1004058
> dd: writing `/dev/sdc2': Input/output error
> 3+0 records in
> 2+0 records out
> #### Attempt to write whole fsblock result write access outside
> #### blkdevice and cause -EIO (returned by blkdev_get_block)
> #### TEST_CASE_END
>
> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
> ---
> mm/filemap.c | 4 +++-
> 1 files changed, 3 insertions(+), 1 deletions(-)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 2c8776b..a23ee8a 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1867,9 +1867,11 @@ inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, i
> } else {
> #ifdef CONFIG_BLOCK
> loff_t isize;
> + unsigned int blksize;
> if (bdev_read_only(I_BDEV(inode)))
> return -EPERM;
> - isize = i_size_read(inode);
> + blksize = block_size(I_BDEV(inode));
> + isize = i_size_read(inode) & ~(blksize - 1);
> if (*pos >= isize) {
> if (*count || *pos > isize)
> return -ENOSPC;
I'm trying to work out how the heck we fixed
http://bugzilla.kernel.org/show_bug.cgi?id=10116
We never merged your patch because it introduced problems. But did we
merge some alternative fix, or does the bug remain in there?
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] mm: fix blkdev size calculation in generic_write_checks
2008-02-26 23:49 ` Andrew Morton
@ 2008-02-27 10:13 ` Dmitri Monakhov
0 siblings, 0 replies; 4+ messages in thread
From: Dmitri Monakhov @ 2008-02-27 10:13 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-kernel, axboe
On 15:49 Tue 26 Feb , Andrew Morton wrote:
> On Wed, 15 Aug 2007 17:52:28 +0400 Dmitry Monakhov <dmonakhov@openvz.org> wrote:
>
> > Currently block device size calculated regardless its
> > bd_block_size. This may result attempt to write outside
> > block device if i_size not aligned to bdev->bd_block_size
> > and result in EIO.
> >
> > #### TEST_CASE_BEGIN
> > # fdisk -l /dev/sdc
> > Disk /dev/sdc: 36.7 GB, 36703918080 bytes
> > 255 heads, 63 sectors/track, 4462 cylinders
> > Units = cylinders of 16065 * 512 = 8225280 bytes
> >
> > Device Boot Start End Blocks Id System
> > /dev/sdc1 * 1 254 2040223+ 83 Ldinux
> > /dev/sdc2 255 379 1004062+ 83 Linux
> > ####
> > #### /dev/sdc2 size not aligned to 4K
> >
> > #### at this time bd_block_size == 512 so generic_write_check
> > #### performed correctly
> > # dd if=/dev/zero of=/dev/sdc2 bs=1k count=7 seek=1004058
> > dd: writing `/dev/sdc2': No space left on device
> > 5+0 records in
> > 4+0 records out
> >
> > #### this bdev contain ext4fs with blksize = 4K
> > # mount /dev/sdc2 /mnt/
> > #### after we mounted this bdev bd_block_size == fsblksize == 4K
> >
> > #### the same write operation failed with EIO
> > # dd if=/dev/zero of=/dev/sdc2 bs=1k count=7 seek=1004058
> > dd: writing `/dev/sdc2': Input/output error
> > 3+0 records in
> > 2+0 records out
> > #### Attempt to write whole fsblock result write access outside
> > #### blkdevice and cause -EIO (returned by blkdev_get_block)
> > #### TEST_CASE_END
> >
> > Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
> > ---
> > mm/filemap.c | 4 +++-
> > 1 files changed, 3 insertions(+), 1 deletions(-)
> >
> > diff --git a/mm/filemap.c b/mm/filemap.c
> > index 2c8776b..a23ee8a 100644
> > --- a/mm/filemap.c
> > +++ b/mm/filemap.c
> > @@ -1867,9 +1867,11 @@ inline int generic_write_checks(struct file *file, loff_t *pos, size_t *count, i
> > } else {
> > #ifdef CONFIG_BLOCK
> > loff_t isize;
> > + unsigned int blksize;
> > if (bdev_read_only(I_BDEV(inode)))
> > return -EPERM;
> > - isize = i_size_read(inode);
> > + blksize = block_size(I_BDEV(inode));
> > + isize = i_size_read(inode) & ~(blksize - 1);
> > if (*pos >= isize) {
> > if (*count || *pos > isize)
> > return -ENOSPC;
>
> I'm trying to work out how the heck we fixed
In fact original issue (wich was reported by me) stil exist
# uname -a
Linux ts52 2.6.25-rc3 #8 SMP Wed Feb 27 11:41:29 MSK 2008 x86_64 x86_64 x86_64
GNU/Linux
# blockdev --getsz /dev/sda7
208782
# blockdev --getbsz /dev/sda7
4096
# dd if=/dev/zero of=/dev/sda7 bs=1k seek=104390 count=1
dd: writing `/dev/sda7': Input/output error
1+0 records in
0+0 records out
0 bytes (0 B) copied, 0.000918887 seconds, 0.0 kB/s
This issue triggered in blkdev_get_block(), which is VFS layer
> http://bugzilla.kernel.org/show_bug.cgi?id=10116
Issue from the bug was triggered in
__generic_make_request()
->bio_check_eod()
->handle_bad_sector()
###Bug's log:
Feb 26 19:17:25 tux attempt to access beyond end of device
Feb 26 19:17:25 tux sr0: rw=0, want=4911744, limit=2097151
###Corresponding code:
printk(KERN_INFO "%s: rw=%ld, want=%Lu, limit=%Lu\n",
bdevname(bio->bi_bdev, b),
bio->bi_rw,
(unsigned long long)bio->bi_sector + bio_sectors(bio),
(long long)(bio->bi_bdev->bd_inode->i_size >> 9));
This means that all vfs checks was already done
(iblock >=max_block(I_BDEV(inode))) was TRUE at this time.
But during __generic_make_request() we have found what "want" was more whan x2
times biger than "limit".
IMHO: this may happens because of bug in DVD driver itself.
>
> We never merged your patch because it introduced problems. But did we
> merge some alternative fix, or does the bug remain in there?
>
^ permalink raw reply [flat|nested] 4+ messages in thread
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2007-08-15 13:52 [PATCH] mm: fix blkdev size calculation in generic_write_checks Dmitry Monakhov
2007-09-12 3:25 ` Andrew Morton
2008-02-26 23:49 ` Andrew Morton
2008-02-27 10:13 ` Dmitri Monakhov
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