Re: [PATCH 2/3] fat: fix time updates for create and delete

From: Namjae Jeon
Date: Thu Nov 15 2012 - 02:02:22 EST

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2012/11/12, OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>:
> OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> writes:
>
>> Namjae Jeon <linkinjeon@xxxxxxxxx> writes:
>>
>>>>> What was difference with XFS, FAT, and MSDOS?
>>> Okay, the description of patch was lacked, So I will resend patch with
>>> specifical test reseult with other filesystem.
>>>>
>>>> BTW, I recall I checked this, and yes, it is strange. But it is
>>>> historical.
>>> "historical" means It is difficult to change ?
>>
>> The timestamp handling was not same with unix fs from initial, and FAT
>> doesn't have inode change timestamp. This historical reason it is not
>> better to change to same with unix fs, and never be possible to support
>> inode change timestamp cleanly.
>
> I.e. the user visible change without strong reason is the wrong.

1)If we consider the code for FAT and MSDOS to be same with respect to
timing updates - there there is difference in code as mentioned below:
a) For:vfat_rmdir()
inode->i_mtime = inode->i_atime = CURRENT_TIME_SEC;
For:msdos_rmdir()
inode->i_ctime = CURRENT_TIME_SEC;

b) For: vfat_unlink()
inode->i_mtime = inode->i_atime = CURRENT_TIME_SEC;
For: msdos_unlink()
inode->i_ctime = CURRENT_TIME_SEC;

So, atleast the uniformity in the code is missing for MSDOS and VFAT.

2) Regarding timings information
Original timings on VFAT:
#> mkdir parent
#> stat parent
File type: directory
I-node number: 30
Mode: 40755 (octal)
Link count: 2
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Thu Jan 1 00:01:29 2012
Last file access: Thu Jan 1 00:01:29 2012
Last file modification: Thu Jan 1 00:01:29 2012
#>
#> echo "hello" > parent/childfile
#> stat parent
File type: directory
I-node number: 30
Mode: 40755 (octal)
Link count: 2
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Thu Jan 1 00:01:45 2012
Last file access: Thu Jan 1 00:01:45 2012
Last file modification: Thu Jan 1 00:01:45 2012
#>
#> mkdir parent/childdir
#> stat parent
File type: directory
I-node number: 30
Mode: 40755 (octal)
Link count: 3
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Thu Jan 1 00:01:56 2012
Last file access: Thu Jan 1 00:01:56 2012
Last file modification: Thu Jan 1 00:01:56 2012
#> rm parent/childfile
#> stat parent
File type: directory
I-node number: 30
Mode: 40755 (octal)
Link count: 3
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Thu Jan 1 00:01:56 2012
Last file access: Thu Jan 1 00:02:12 2012
Last file modification: Thu Jan 1 00:02:12 2012
#> rm -rf parent/childdir
#> stat parent
File type: directory
I-node number: 30
Mode: 40755 (octal)
Link count: 2
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Thu Jan 1 00:01:56 2012
Last file access: Thu Jan 1 00:02:24 2012
Last file modification: Thu Jan 1 00:02:24 2012

For timing information comparison after changes in VFAT -> for VFAT ,
EXT4 and XFS
########################################################################
VFAT Filesystem with timestamp patch
########################################################################
#> mkdir parent
#> stat parent
File type: directory
I-node number: 29
Mode: 40755 (octal)
Link count: 2
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Sun Jan 1 00:11:10 2012
Last file access: Sun Jan 1 00:11:10 2012
Last file modification: Sun Jan 1 00:11:10 2012
#>
#> echo "hello" parent/childfile
hello parent/childfile
#> echo "hello" > parent/childfile
#> stat parent
File type: directory
I-node number: 29
Mode: 40755 (octal)
Link count: 2
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Sun Jan 1 00:12:22 2012
Last file access: Sun Jan 1 00:11:10 2012
Last file modification: Sun Jan 1 00:12:22 2012
#>
#>
#> mkdir parent/childdir
#> stat parent
File type: directory
I-node number: 29
Mode: 40755 (octal)
Link count: 3
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Sun Jan 1 00:13:10 2012
Last file access: Sun Jan 1 00:11:10 2012
Last file modification: Sun Jan 1 00:13:10 2012
#>
#> rm parent/childfile
#> stat parent
File type: directory
I-node number: 29
Mode: 40755 (octal)
Link count: 3
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Sun Jan 1 00:13:38 2012
Last file access: Sun Jan 1 00:11:10 2012
Last file modification: Sun Jan 1 00:13:38 2012
#> rm parent/childdir
rm: parent/childdir: is a directory
#> rm -rf parent/childdir
#> stat parent
File type: directory
I-node number: 29
Mode: 40755 (octal)
Link count: 2
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Sun Jan 1 00:13:59 2012
Last file access: Sun Jan 1 00:11:10 2012
Last file modification: Sun Jan 1 00:13:59 2012
#>

########################################################################
EXT4 Filesystem
########################################################################
#> cd /dtv/usb/sdb2
#> pwd
/dtv/usb/sdb2
#>
#> mkdir parent
#> stat parent
File type: directory
I-node number: 12
Mode: 40755 (octal)
Link count: 2
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Sun Jan 1 00:14:44 2012
Last file access: Sun Jan 1 00:14:44 2012
Last file modification: Sun Jan 1 00:14:44 2012
#>
#> echo "hello" > parent/childfile
#> stat parent
File type: directory
I-node number: 12
Mode: 40755 (octal)
Link count: 2
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Sun Jan 1 00:15:04 2012
Last file access: Sun Jan 1 00:14:44 2012
Last file modification: Sun Jan 1 00:15:04 2012
#> mkdir parent/childdir
#> stat parent
File type: directory
I-node number: 12
Mode: 40755 (octal)
Link count: 3
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Sun Jan 1 00:15:34 2012
Last file access: Sun Jan 1 00:14:44 2012
Last file modification: Sun Jan 1 00:15:34 2012
#>
#> rm parent/childfile
#> stat parent
File type: directory
I-node number: 12
Mode: 40755 (octal)
Link count: 3
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Sun Jan 1 00:15:53 2012
Last file access: Sun Jan 1 00:14:44 2012
Last file modification: Sun Jan 1 00:15:53 2012
#>
#> rm -rf parent/childdir
#> stat parent
File type: directory
I-node number: 12
Mode: 40755 (octal)
Link count: 2
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 4096 bytes
Blocks allocated: 8
Last status change: Sun Jan 1 00:16:09 2012
Last file access: Sun Jan 1 00:14:44 2012
Last file modification: Sun Jan 1 00:16:09 2012
#>

####################################################################
XFS
####################################################################
#> mkdir parent
#> stat parent
File type: directory
I-node number: 131
Mode: 40755 (octal)
Link count: 2
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 6 bytes
Blocks allocated: 0
Last status change: Sun Jan 1 00:17:06 2012
Last file access: Sun Jan 1 00:17:06 2012
Last file modification: Sun Jan 1 00:17:06 2012
#>
#> echo "hello" > parent/childfile
#> stat parent
File type: directory
I-node number: 131
Mode: 40755 (octal)
Link count: 2
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 22 bytes
Blocks allocated: 0
Last status change: Sun Jan 1 00:17:22 2012
Last file access: Sun Jan 1 00:17:06 2012
Last file modification: Sun Jan 1 00:17:22 2012
#>
#> mkdir parent/childdir
#> stat parent
File type: directory
I-node number: 131
Mode: 40755 (octal)
Link count: 3
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 37 bytes
Blocks allocated: 0
Last status change: Sun Jan 1 00:17:36 2012
Last file access: Sun Jan 1 00:17:06 2012
Last file modification: Sun Jan 1 00:17:36 2012
#>
#>
#> rm parent/childfile
#> stat parent
File type: directory
I-node number: 131
Mode: 40755 (octal)
Link count: 3
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 21 bytes
Blocks allocated: 0
Last status change: Sun Jan 1 00:17:51 2012
Last file access: Sun Jan 1 00:17:06 2012
Last file modification: Sun Jan 1 00:17:51 2012
#>
#> rm -rf parent/childdir
#> stat parent
File type: directory
I-node number: 131
Mode: 40755 (octal)
Link count: 2
Ownership: UID=0 GID=0
Preferred I/O block size: 4096 bytes
File size: 6 bytes
Blocks allocated: 0
Last status change: Sun Jan 1 00:17:58 2012
Last file access: Sun Jan 1 00:17:06 2012
Last file modification: Sun Jan 1 00:17:58 2012
#>

As can be seen from the 'stat' information - the timing information
appears same for VFAT like EXT4/XFS after changes.
Please let me know your opinion.

Thanks.

> --
> OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
>
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Next message: Wendy Drake: "[no subject]"
Previous message: Wen Congyang: "[Patch v5 3/7] acpi_memhotplug.c: fix memory leak when memory device is unbound from the module acpi_memhotplug"
In reply to: OGAWA Hirofumi: "Re: [PATCH 2/3] fat: fix time updates for create and delete"
Next in thread: OGAWA Hirofumi: "Re: [PATCH 2/3] fat: fix time updates for create and delete"
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