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Date: Thu, 24 Apr 2008 00:28:01 +0530
From: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To: Theodore Tso <tytso@....EDU>
Cc: linux-ext4@...r.kernel.org
Subject: Re: What's cooking in e2fsprogs.git (topics)
On Mon, Apr 21, 2008 at 12:41:44PM -0400, Theodore Tso wrote:
>
> * ak/undo-mgr (Mon Aug 13 15:56:26 2007 +0530) 6 commits
> - Add test cases for undoe2fs: u_undoe2fs_mke2fs and
> u_undoe2fs_tune2fs
> - Fix the resize inode test case
> - tune2fs: Support for large inode migration.
> - mke2fs: Add support for the undo I/O manager.
> - Add undoe2fs command
> - libext2fs: Add undo I/O manager
>
> These patches have been *significantly* rototilled.
>
> * The test cases weren't correctly setting and deleting the
> test_name.ok and test_name.failed files
>
> * mke2fs would bomb out with an incomprehensible error message
> if run twice in a row, or if the user didn't have write access
> to /var/lib/e2fsprogs (some users run mke2fs as a non-root
> user!)
>
> * the undoe2fs program was calling com_err and passing
> in uninitialized retval values, and was otherwise confused
> about how to do proper error handling, resulting in garbage
> getting printed if the file passed in didn't exist
>
> * there was a terrible performance problem because in the
> mke2fs case, the undo manager was using a tdb_data_size of
> 512.
>
> * I added the ability to configure the location of the scratch
> dirctory via mke2fs.conf for mk2efs. What we should do for
> tune2fs is less clear, and still needs to be addressed. It
> is also possible to force an undo file to be always created,
> and not just when doing a lazy inode table initialization.
> By using a 4k instead of 512 tdb_data_size, the time to
> speed up an mke2fs was cut in half, while still using an
> undo file. I suspect if we force the tdb_data_size to be
> even larger, say 32k or 64k the overhead would shrink even
> more.
>
> Unfortunately, there appears to be some kind of data
> corruption bug if I force a tdb_data_size of 32768, so I'm not
> entirely sure I trust the undo manager to be working
> correctly. The undo_manager code itself needs a pretty
> serious auditing and checking to make sure it's doing the
> right thing with large tdb_data_sizes.
>
The bug was in the changes added to support block size via set_options
We had two records in the data for blocksize. one 1024. configured via
set_blk_size and other 32K configured via set_options. So the undoe2fs
was replaying with 1K as the block size.
The below changes get everything working for me. The patch is not clean.
so they are not to apply. I still need to think a little bit more about
what to do when we attempt to read tdb_data_size from the end of file
system. Will send the cleanup patch later.
Let me know whether you want to keep the debug printf
diff --git a/lib/ext2fs/undo_io.c b/lib/ext2fs/undo_io.c
index 9bee1b6..4ad0fd6 100644
--- a/lib/ext2fs/undo_io.c
+++ b/lib/ext2fs/undo_io.c
@@ -169,6 +169,9 @@ static errcode_t write_block_size(TDB_CONTEXT *tdb, int block_size)
tdb_key.dsize = sizeof("filesystem BLKSIZE");
tdb_data.dptr = (unsigned char *)&(block_size);
tdb_data.dsize = sizeof(block_size);
+#ifdef DEBUG
+ printf("Setting blocksize %d\n", block_size);
+#endif
retval = tdb_store(tdb, tdb_key, tdb_data, TDB_INSERT);
if (retval == -1) {
@@ -182,13 +185,14 @@ static errcode_t undo_write_tdb(io_channel channel,
unsigned long block, int count)
{
- int size, loop_count = 0, i;
+ int size, i;
unsigned long block_num, backing_blk_num;
errcode_t retval = 0;
ext2_loff_t offset;
struct undo_private_data *data;
TDB_DATA tdb_key, tdb_data;
char *read_ptr;
+ unsigned long end_block;
data = (struct undo_private_data *) channel->private_data;
@@ -208,21 +212,26 @@ static errcode_t undo_write_tdb(io_channel channel,
size = count * channel->block_size;
}
+#ifdef DEBUG
+ printf("Writing at %ld of size %ld\n", block, size);
+#endif
/*
* Data is stored in tdb database as blocks of tdb_data_size size
* This helps in efficient lookup further.
*
* We divide the disk to blocks of tdb_data_size.
*/
+ /*FIXME need to check end of file system. */
- block_num = ((block*channel->block_size)+data->offset) /
- data->tdb_data_size;
-
- loop_count = (size + data->tdb_data_size -1) /
- data->tdb_data_size;
+ offset = (block * channel->block_size) + data->offset ;
+ block_num = offset / data->tdb_data_size;
+ end_block = (offset + size) / data->tdb_data_size;
+#ifdef DEBUG
+ printf("Writing from %ld to %ld\n", block_num, end_block);
+#endif
tdb_transaction_start(data->tdb);
- for (i = 0; i < loop_count; i++) {
+ while (block_num <= end_block ) {
tdb_key.dptr = (unsigned char *)&block_num;
tdb_key.dsize = sizeof(block_num);
@@ -231,8 +240,11 @@ static errcode_t undo_write_tdb(io_channel channel,
* Check if we have the record already
*/
if (tdb_exists(data->tdb, tdb_key)) {
-
/* Try the next block */
+#ifdef DEBUG
+ printf("The block %d already exist in database\n",
+ block_num);
+#endif
block_num++;
continue;
}
@@ -258,6 +270,9 @@ static errcode_t undo_write_tdb(io_channel channel,
}
memset(read_ptr, 0, count);
+#ifdef DEBUG
+ printf("Reading from %ld to %ld\n", backing_blk_num, count);
+#endif
retval = io_channel_read_blk(data->real, backing_blk_num,
-count, read_ptr);
@@ -276,10 +291,22 @@ static errcode_t undo_write_tdb(io_channel channel,
printf("Printing with key %ld data %x and size %d\n",
block_num,
tdb_data.dptr,
- channel->tdb_data_size);
+ data->tdb_data_size);
#endif
- data->tdb_written = 1;
+ if (!data->tdb_written) {
+ data->tdb_written = 1;
+
+ /* Write the blocksize to tdb file */
+ retval = write_block_size(data->tdb,
+ data->tdb_data_size);
+ if (retval) {
+ tdb_transaction_cancel(data->tdb);
+ retval = EXT2_ET_TDB_ERR_IO;
+ free(read_ptr);
+ return retval;
+ }
+ }
retval = tdb_store(data->tdb, tdb_key, tdb_data, TDB_INSERT);
if (retval == -1) {
/*
@@ -417,11 +444,6 @@ static errcode_t undo_set_blksize(io_channel channel, int blksize)
*/
if (!data->tdb_data_size) {
data->tdb_data_size = blksize;
-
- /* Write it to tdb file */
- retval = write_block_size(data->tdb, data->tdb_data_size);
- if (retval)
- return retval;
}
channel->block_size = blksize;
@@ -540,12 +562,6 @@ static errcode_t undo_set_option(io_channel channel, const char *option,
return EXT2_ET_INVALID_ARGUMENT;
if (!data->tdb_data_size || !data->tdb_written) {
data->tdb_data_size = tmp;
-
- /* Write it to tdb file */
- retval = write_block_size(data->tdb,
- data->tdb_data_size);
- if (retval)
- return retval;
}
return 0;
}
diff --git a/misc/mke2fs.c b/misc/mke2fs.c
index 593b743..be772ee 100644
--- a/misc/mke2fs.c
+++ b/misc/mke2fs.c
@@ -1745,6 +1745,7 @@ static int should_do_undo(const char *name)
io_manager manager = unix_io_manager;
int csum_flag, force_undo;
+
csum_flag = EXT2_HAS_RO_COMPAT_FEATURE(&fs_param,
EXT4_FEATURE_RO_COMPAT_GDT_CSUM);
force_undo = get_int_from_profile(fs_types, "force_undo", 0);
@@ -1873,7 +1874,7 @@ int main (int argc, char *argv[])
com_err(device_name, retval, _("while setting up superblock"));
exit(1);
}
-#if 0 /* XXX bug in undo_io.c if we set this? */
+#if 1 /* XXX bug in undo_io.c if we set this? */
io_channel_set_options(fs->io, "tdb_data_size=32768");
#endif
--
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