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Subject: Re: [PATCH] e2fsprogs: Try again to solve unreliable io case
To:     "Darrick J. Wong" <djwong@kernel.org>,
        Haotian Li <lihaotian9@huawei.com>
CC:     Ext4 Developers List <linux-ext4@vger.kernel.org>,
        "Theodore Y. Ts'o" <tytso@mit.edu>,
        "harshad shirwadkar," <harshadshirwadkar@gmail.com>,
        linfeilong <linfeilong@huawei.com>
References: <d4fd737d-4280-1aee-32ae-36b303e6644d@huawei.com>
 <20210420150835.GA3122213@magnolia>
From:   Zhiqiang Liu <liuzhiqiang26@huawei.com>
Message-ID: <303e599d-6c31-d03a-3d56-6d678703b23e@huawei.com>
Date:   Thu, 22 Apr 2021 21:03:29 +0800
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On 2021/4/20 23:08, Darrick J. Wong wrote:
> On Tue, Apr 20, 2021 at 03:18:05PM +0800, Haotian Li wrote:
>> If some I/O error occured during e2fsck, for example the
>> fibre channel connections are flasky, the e2fsck may exit.
>> Try again in these I/O error cases may help e2fsck
>> successfully execute and fix the disk correctly.
>>
>> We may try five times when io_channel_write/read failed.
>> Enable this option by setting true on unreliable_io in
>> configure file "e2fsck.conf".
> 
> Why not set 'io_max_retries = 5' in e2fsck.conf and feed that to the io
> manager directly?  That would be more flexible than a boolean that
> triggers a hardwired retry counter.
> 
> --D
>
Thanks for your suggestion.

We will have a try, and send the v2 patch.

Regards
Zhiqiang Liu
>>
>> Signed-off-by: Haotian Li <lihaotian9@huawei.com>
>> Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com>
>> ---
>>  e2fsck/unix.c           |   7 +++
>>  lib/ext2fs/ext2_io.h    |   3 ++
>>  lib/ext2fs/ext2fs.h     |   2 +-
>>  lib/ext2fs/io_manager.c | 102 ++++++++++++++++++++++++++++++----------
>>  lib/ext2fs/openfs.c     |   2 +
>>  lib/ext2fs/unix_io.c    |   4 ++
>>  6 files changed, 93 insertions(+), 27 deletions(-)
>>
>> diff --git a/e2fsck/unix.c b/e2fsck/unix.c
>> index c5f9e441..faa2f77d 100644
>> --- a/e2fsck/unix.c
>> +++ b/e2fsck/unix.c
>> @@ -1398,6 +1398,7 @@ int main (int argc, char *argv[])
>>  	int journal_size;
>>  	int sysval, sys_page_size = 4096;
>>  	int old_bitmaps;
>> +	int unreliable_io;
>>  	__u32 features[3];
>>  	char *cp;
>>  	enum quota_type qtype;
>> @@ -1496,6 +1497,12 @@ restart:
>>  			    &old_bitmaps);
>>  	if (!old_bitmaps)
>>  		flags |= EXT2_FLAG_64BITS;
>> +
>> +	profile_get_boolean(ctx->profile, "options", "unreliable_io", 0, 0,
>> +			    &unreliable_io);
>> +	if (unreliable_io)
>> +		flags |= EXT2_FLAG_UNRELIABLE_IO;
>> +
>>  	if ((ctx->options & E2F_OPT_READONLY) == 0) {
>>  		flags |= EXT2_FLAG_RW;
>>  		if (!(ctx->mount_flags & EXT2_MF_ISROOT &&
>> diff --git a/lib/ext2fs/ext2_io.h b/lib/ext2fs/ext2_io.h
>> index 8fe5b323..38d23a1b 100644
>> --- a/lib/ext2fs/ext2_io.h
>> +++ b/lib/ext2fs/ext2_io.h
>> @@ -34,8 +34,10 @@ typedef struct struct_io_stats *io_stats;
>>  #define CHANNEL_FLAGS_DISCARD_ZEROES	0x02
>>  #define CHANNEL_FLAGS_BLOCK_DEVICE	0x04
>>  #define CHANNEL_FLAGS_THREADS		0x08
>> +#define CHANNEL_FLAGS_UNRELIABLE_IO     0x10
>>
>>  #define io_channel_discard_zeroes_data(i) (i->flags & CHANNEL_FLAGS_DISCARD_ZEROES)
>> +#define UNRELIABLE_IO_RETRY_TIMES 5
>>
>>  struct struct_io_channel {
>>  	errcode_t	magic;
>> @@ -107,6 +109,7 @@ struct struct_io_manager {
>>  #define IO_FLAG_FORCE_BOUNCE	0x0008
>>  #define IO_FLAG_THREADS		0x0010
>>  #define IO_FLAG_NOCACHE		0x0020
>> +#define IO_FLAG_UNRELIABLE_IO   0x0040
>>
>>  /*
>>   * Convenience functions....
>> diff --git a/lib/ext2fs/ext2fs.h b/lib/ext2fs/ext2fs.h
>> index df150f00..4ce5e311 100644
>> --- a/lib/ext2fs/ext2fs.h
>> +++ b/lib/ext2fs/ext2fs.h
>> @@ -207,7 +207,7 @@ typedef struct ext2_file *ext2_file_t;
>>  #define EXT2_FLAG_BBITMAP_TAIL_PROBLEM	0x1000000
>>  #define EXT2_FLAG_IBITMAP_TAIL_PROBLEM	0x2000000
>>  #define EXT2_FLAG_THREADS		0x4000000
>> -
>> +#define EXT2_FLAG_UNRELIABLE_IO         0x8000000
>>  /*
>>   * Special flag in the ext2 inode i_flag field that means that this is
>>   * a new inode.  (So that ext2_write_inode() can clear extra fields.)
>> diff --git a/lib/ext2fs/io_manager.c b/lib/ext2fs/io_manager.c
>> index 996c31a1..f062ef0a 100644
>> --- a/lib/ext2fs/io_manager.c
>> +++ b/lib/ext2fs/io_manager.c
>> @@ -61,66 +61,116 @@ errcode_t io_channel_write_byte(io_channel channel, unsigned long offset,
>>  				int count, const void *data)
>>  {
>>  	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
>> -
>> -	if (channel->manager->write_byte)
>> -		return channel->manager->write_byte(channel, offset,
>> +	errcode_t ret = EXT2_ET_UNIMPLEMENTED;
>> +       int retry_times = (channel->flags & CHANNEL_FLAGS_UNRELIABLE_IO) ?
>> +               UNRELIABLE_IO_RETRY_TIMES : 0;
>> +retry:
>> +	if (channel->manager->write_byte) {
>> +		ret = channel->manager->write_byte(channel, offset,
>>  						    count, data);
>> -
>> -	return EXT2_ET_UNIMPLEMENTED;
>> +		if (ret && retry_times) {
>> +                        retry_times--;
>> +                        goto retry;
>> +               }
>> +	}
>> +	return ret;
>>  }
>>
>>  errcode_t io_channel_read_blk64(io_channel channel, unsigned long long block,
>>  				 int count, void *data)
>>  {
>> -	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
>> -
>> -	if (channel->manager->read_blk64)
>> -		return (channel->manager->read_blk64)(channel, block,
>> +       EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
>> +	errcode_t ret = 0;
>> +	int retry_times = (channel->flags & CHANNEL_FLAGS_UNRELIABLE_IO) ?
>> +		UNRELIABLE_IO_RETRY_TIMES : 0;
>> +retry_read_blk64:
>> +	if (channel->manager->read_blk64) {
>> +		ret = (channel->manager->read_blk64)(channel, block,
>>  						      count, data);
>> +		if (ret && retry_times) {
>> +			retry_times--;
>> +			goto retry_read_blk64;
>> +		}
>> +		return ret;
>> +	}
>>
>>  	if ((block >> 32) != 0)
>>  		return EXT2_ET_IO_CHANNEL_NO_SUPPORT_64;
>> -
>> -	return (channel->manager->read_blk)(channel, (unsigned long) block,
>> +retry_read_blk:
>> +	ret = (channel->manager->read_blk)(channel, (unsigned long) block,
>>  					     count, data);
>> +	if (ret && retry_times) {
>> +		retry_times--;
>> +               goto retry_read_blk;
>> +       }
>> +	return ret;
>>  }
>>
>> +
>>  errcode_t io_channel_write_blk64(io_channel channel, unsigned long long block,
>>  				 int count, const void *data)
>>  {
>>  	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
>> -
>> -	if (channel->manager->write_blk64)
>> -		return (channel->manager->write_blk64)(channel, block,
>> +	errcode_t ret = 0;
>> +       int retry_times = (channel->flags & CHANNEL_FLAGS_UNRELIABLE_IO) ?
>> +                UNRELIABLE_IO_RETRY_TIMES : 0;
>> +retry_write_blk64:
>> +	if (channel->manager->write_blk64) {
>> +		ret = (channel->manager->write_blk64)(channel, block,
>>  						       count, data);
>> +		if (ret && retry_times) {
>> +                        retry_times--;
>> +                        goto retry_write_blk64;
>> +               }
>> +               return ret;
>> +        }
>>
>>  	if ((block >> 32) != 0)
>>  		return EXT2_ET_IO_CHANNEL_NO_SUPPORT_64;
>> -
>> -	return (channel->manager->write_blk)(channel, (unsigned long) block,
>> +retry_write_blk:
>> +	ret = (channel->manager->write_blk)(channel, (unsigned long) block,
>>  					     count, data);
>> +	if (ret && retry_times) {
>> +               retry_times--;
>> +               goto retry_write_blk;
>> +       }
>> +	return ret;
>>  }
>>
>>  errcode_t io_channel_discard(io_channel channel, unsigned long long block,
>>  			     unsigned long long count)
>>  {
>>  	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
>> -
>> -	if (channel->manager->discard)
>> -		return (channel->manager->discard)(channel, block, count);
>> -
>> -	return EXT2_ET_UNIMPLEMENTED;
>> +	errcode_t ret = EXT2_ET_UNIMPLEMENTED;
>> +	int retry_times = (channel->flags & CHANNEL_FLAGS_UNRELIABLE_IO) ?
>> +	                UNRELIABLE_IO_RETRY_TIMES : 0;
>> +retry:
>> +	if (channel->manager->discard) {
>> +		ret = (channel->manager->discard)(channel, block, count);
>> +		if (ret && retry_times) {
>> +                       retry_times--;
>> +                       goto retry;
>> +               }
>> +	}
>> +	return ret;
>>  }
>>
>>  errcode_t io_channel_zeroout(io_channel channel, unsigned long long block,
>>  			     unsigned long long count)
>>  {
>>  	EXT2_CHECK_MAGIC(channel, EXT2_ET_MAGIC_IO_CHANNEL);
>> -
>> -	if (channel->manager->zeroout)
>> -		return (channel->manager->zeroout)(channel, block, count);
>> -
>> -	return EXT2_ET_UNIMPLEMENTED;
>> +	errcode_t ret = EXT2_ET_UNIMPLEMENTED;
>> +       int retry_times = (channel->flags & CHANNEL_FLAGS_UNRELIABLE_IO) ?
>> +                        UNRELIABLE_IO_RETRY_TIMES : 0;
>> +retry:
>> +	if (channel->manager->zeroout) {
>> +		ret = (channel->manager->zeroout)(channel, block, count);
>> +		if (ret && retry_times) {
>> +                        retry_times--;
>> +                        goto retry;
>> +               }
>> +       }
>> +	return ret;
>>  }
>>
>>  errcode_t io_channel_alloc_buf(io_channel io, int count, void *ptr)
>> diff --git a/lib/ext2fs/openfs.c b/lib/ext2fs/openfs.c
>> index 5ec8ed5c..a98a5815 100644
>> --- a/lib/ext2fs/openfs.c
>> +++ b/lib/ext2fs/openfs.c
>> @@ -172,6 +172,8 @@ errcode_t ext2fs_open2(const char *name, const char *io_options,
>>  		io_flags |= IO_FLAG_DIRECT_IO;
>>  	if (flags & EXT2_FLAG_THREADS)
>>  		io_flags |= IO_FLAG_THREADS;
>> +	if (flags & EXT2_FLAG_UNRELIABLE_IO)
>> +		io_flags |= IO_FLAG_UNRELIABLE_IO;
>>  	retval = manager->open(fs->device_name, io_flags, &fs->io);
>>  	if (retval)
>>  		goto cleanup;
>> diff --git a/lib/ext2fs/unix_io.c b/lib/ext2fs/unix_io.c
>> index 64eee342..845a1e16 100644
>> --- a/lib/ext2fs/unix_io.c
>> +++ b/lib/ext2fs/unix_io.c
>> @@ -837,6 +837,10 @@ static errcode_t unix_open_channel(const char *name, int fd,
>>  		}
>>  	}
>>  #endif
>> +	if (flags & IO_FLAG_UNRELIABLE_IO) {
>> +		io->flags |= CHANNEL_FLAGS_UNRELIABLE_IO;
>> +	}
>> +
>>  	*channel = io;
>>  	return 0;
>>
>> -- 
>> 2.23.0
>>
> 
> .
>