[U-Boot] ext4 delete file fails when ext4 extents enabled in filesystem

[Thomas Schaefer]

> -----Ursprüngliche Nachricht-----
> Von: Brüns, Stefan [mailto:Stefan.Bruens at rwth-aachen.de] 
> Gesendet: Freitag, 2. September 2016 13:43
> An: Thomas Schaefer
> Cc: u-boot at lists.denx.de; Michael Walle
> Betreff: Re: ext4 delete file fails when ext4 extents enabled in filesystem

> On Donnerstag, 1. September 2016 19:25:30 CEST you wrote:
> > On Donnerstag, 1. September 2016 16:08:51 CEST you wrote:
> > > Hi Stefan,
> > > 
> > > applying patch [U-Boot,v4,06/13]ext4 and Michael Walles patch 
> > > [U-Boot,v4,3/4]ext4, I'm now able to write into directories on ext4 
> > > fs from u-boot. However, when deleting a given file (i.e. when 
> > > writing to an existing filename), u-boot crashes when ext4 extents 
> > > are enabled.
> > > 
> > > Some debugging showd that blknr from 'read_allocated_block' function 
> > > returns negative value. I can only guess, maybe its due to 64 bit 
> > > values calculated from ee_start_hi and ee_start_lo entries in the 
> > > ext4_extent structure.
> > > 
> > > When disabling extents in the ext4 fs, deleting a given file is working.
> > 
> > Hi Thomas,
> > 
> > U-boots ext4 implementation currently does not support 64bit or even 
> > 48bit block numbers, so this may be the cause.
> > 
> > Can you provide some information about your test setup?
> > 
> > You can use the debugsfs ext tool to gather some information about the 
> > problematic file. Just access the filesystem with:
> > 
> > /sbin/debugfs /dev/sda1  ;  (or whatever your partion name is)
> > 
> >   or
> > 
> > /sbin/debugfs /path/to/imagefile
> > 
> > debugfs supports commands like cd, stat, ls. stat gives you the block 
> > number list.
> > 
> > Kind regards,
> > 
> > Stefan
>
> Hi Thomas,
>
> short followup:
>
> read_allocated_blocks returns either 0 or -1 in case of an error. 
> Unfortunately, the return value is only checked for 0 equality in most/all? 
> cases, and seemingly my patch series introduced some more occasions.
>
>
> Now, what *should* read_allocated_blocks return in case of an error? Either:
>
> - 0: a file block can never be allocated as block 0, as that is always in use by the superblock and/or the bootsector block.
>
> - <0: Extents allow 48 bit block numbers. "Limiting" the return value to the positive half of int64_t for valid block numbers and and reserving negative values for error codes is fine.
>
> I would go for negative error codes, as these are more expressive. Comments/ opinions welcome!
>
>
> I will update the patch series for correct checking of read_allocated_blocks return values and fix all the other block number checks.
>
> Anyway, it would be good to know why *exactly* read_allocated_blocks returns an error code in your case. Do you remember the exact negative value returned (there are -EINVAL and -> > > > > ENOMEN, and many several unspecific uses of 0 and -1). 
>
> Can you provide a disk image of the failing file system?
>
> Kind regards,
>
> Stefan

Hi Stefan,

the attachment contains an image file that causes u-boot to crash when trying to overwrite existing files in ext4 fs.

Calling debugfs show the following output

root at s1909:~# /sbin/debugfs /dev/mmcblk0p1
debugfs 1.43-WIP (18-May-2015)
debugfs:  ls
 2  (12) .    2  (12) ..    11  (20) lost+found    12  (12) foo
 7729  (4040) images
debugfs:  ls foo
 12  (12) .    2  (12) ..    13  (16) test.bin    14  (4056) test2.bin
debugfs:  stat foo/test.bin
Inode: 13   Type: regular    Mode:  0644   Flags: 0x80000
Generation: 2312001584    Version: 0x00000000:00000001
User:     0   Group:     0   Size: 559364
File ACL: 0    Directory ACL: 0
Links: 1   Blockcount: 1096
Fragment:  Address: 0    Number: 0    Size: 0
 ctime: 0x57c93d53:3a2e2ac0 -- Fri Sep  2 08:50:27 2016
 atime: 0x57c98a2b:00001708 -- Fri Sep  2 14:18:19 2016
 mtime: 0x57c93d53:3a2e2ac0 -- Fri Sep  2 08:50:27 2016
crtime: 0x57c93d53:243eee64 -- Fri Sep  2 08:50:27 2016
Size of extra inode fields: 32
EXTENTS:
(0-136):32852-32988
debugfs:  stat foo/test2.bin
Inode: 14   Type: regular    Mode:  0644   Flags: 0x80000
Generation: 2312001585    Version: 0x00000000:00000001
User:     0   Group:     0   Size: 559364
File ACL: 0    Directory ACL: 0
Links: 1   Blockcount: 1096
Fragment:  Address: 0    Number: 0    Size: 0
 ctime: 0x57c93d5d:e206ed50 -- Fri Sep  2 08:50:37 2016
 atime: 0x57c93d5d:cc17b0f4 -- Fri Sep  2 08:50:37 2016
 mtime: 0x57c93d5d:e206ed50 -- Fri Sep  2 08:50:37 2016
crtime: 0x57c93d5d:cc17b0f4 -- Fri Sep  2 08:50:37 2016
Size of extra inode fields: 32
EXTENTS:
(0-136):32989-33125
debugfs: q


Thank you and best regards,
Thomas
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