On Mon, 23 Jun 2008, Aneesh Kumar K.V wrote:
On Fri, Jun 20, 2008 at 09:21:48AM +0000, Holger Kiehl wrote:
On Fri, 20 Jun 2008, Theodore Tso wrote:
On Fri, Jun 20, 2008 at 08:32:52AM +0000, Holger Kiehl wrote:
It sounds like i_size is actually dropping in
size at some pointer long after the file was written. If I had to
sorry, "at some point"...
guess the value in the inode cache is correct; and perhaps so is the
value on the journal. But somehow, the wrong value is getting written
to disk
Or, "the right value is never getting written to disk". (Which as I
think about it is more likely; it's likely that an update to i_size is
getting *lost*, perhaps because the delalloc code is possibly
modifying i_size without starting a transaction first. Again this is
just a guess.)
What I find strange is that the missing parts of the file are not for
example exactly 512 or 1024 or 4096 bytes it is mostly some odd number
of bytes.
Is there any chance the truncation point is related to how the program
is writing its output file? i.e., if it is a text file, is the
truncation happening after a new-line or when the stdio library might
have done an explicit or implicit fflush()?
When the benchmark runs it writes to stdout and with tee to the result
file. It first writes some information about the system, prepares the
test files (creates lots of small files), calls sync and then starts
the test. Then every minute one line gets written to the result file.
Often I have seen that everything after the sync was missing. But
sometimes it happened that some parts at the end are missing. But it
was always a clean cut, that is there where no lines that where cut
partially. The lines where always complete.
I found one place where we fail to update i_disksize. Can you try this
patch ?
Yes, I would like to however when I take
ext4-patch-queue-70acdb9605784bd5c4b06e1a19761828a494a337.tar.gz (which is
the current ext4-patch-queue from http://repo.or.cz/w/ext4-patch-queue.git)
and apply those to linux-2.6.26-rc6 I get the following reject:
***************
*** 574,579 ****
INIT_LIST_HEAD(&ei->i_prealloc_list);
spin_lock_init(&ei->i_prealloc_lock);
jbd2_journal_init_jbd_inode(&ei->jinode, &ei->vfs_inode);
return &ei->vfs_inode;
}
--- 574,584 ----
INIT_LIST_HEAD(&ei->i_prealloc_list);
spin_lock_init(&ei->i_prealloc_lock);
jbd2_journal_init_jbd_inode(&ei->jinode, &ei->vfs_inode);
+ ei->i_reserved_data_blocks = 0;
+ ei->i_reserved_meta_blocks = 0;
+ ei->i_allocated_meta_blocks = 0;
+ ei->i_delalloc_reserved_flag = 0;
+ spin_lock_init(&(ei->i_block_reservation_lock));
return &ei->vfs_inode;
}
Which is from delalloc-ext4-ENOSPC-handling.patch. What am I doing wrong?
I could apply this by hand but I do not know if this would be correct.
Please can anyone advice what I need to do?
Thanks,
Holger
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