[Bug 12793] New: ext4 gives wrong errno with too long extended attribute values

[Bug 12793] New: ext4 gives wrong errno with too long extended attribute values

[bugme-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=12793

           Summary: ext4 gives wrong errno with too long extended attribute
                    values
           Product: File System
           Version: 2.5
     KernelVersion: 2.6.29-rc6
          Platform: All
        OS/Version: Linux
              Tree: Mainline
            Status: NEW
          Severity: normal
          Priority: P1
         Component: ext4
        AssignedTo: fs_ext4@kernel-bugs.osdl.org
        ReportedBy: betelgeuse@gentoo.org


Latest working kernel version: haven't seen it working
Earliest failing kernel version: 2.6.28-gentoo-r1 had the same issue
Distribution: Gentoo
Hardware Environment: SMP Sun Mar 1 14:15:44 EET 2009 i686 Intel(R) Core(TM)2
CPU 6600 @ 2.40GHz GenuineIntel GNU/Linux
Software Environment: Gentoo ~x86
Problem Description:

>From man attr_set:

       attr_set will fail if one or more of the following are true:

       [ENOATTR]        The attribute name given is not associated with the
indicated filesystem object and the ATTR_REPLACE flag bit was set.

       [E2BIG]          The value of the given attribute is too large, it
exceeds the maximum allowable size of an attribute value.

This is what the test script gives for ext4:

3900                                            
4000                                                                            
4100                                                                            
Traceback (most recent call last):                                              
  File "test_xattr.py", line 10, in <module>                                    
    xattr.set('/mnt/test/header.txt','user.test',s)                             
IOError: [Errno 28] No space left on device   

This is what xfs gives:

65500
65600
Traceback (most recent call last):
  File "test_xattr.py", line 10, in <module>
    xattr.set('/mnt/test/header.txt','user.test',s)
IOError: [Errno 7] Argument list too long

>>> errno.errorcode[7]
'E2BIG'
>>> errno.errorcode[28]
'ENOSPC'

Steps to reproduce:

betelgeuse@pena ~/python $ cat test_xattr.py
import xattr
hundred = ''
for i in range(100):
        hundred+='a'

s=hundred

while True:
        print len(s)
        xattr.set('/mnt/test/header.txt','user.test',s)
        s+=hundred


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[Bug 12793] ext4 gives wrong errno with too long extended attribute values

[bugzilla-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=12793


Narendra Prasad Madanapalli <narendramind@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |narendramind@gmail.com




--- Comment #1 from Narendra Prasad Madanapalli <narendramind@gmail.com>  2009-08-07 15:02:16 ---
The following patch fixes the issue.

====Patch starts
iff -uNr linux-2.6.30.3-orig/fs/ext4/xattr.c linux-2.6.30.3-fix/fs/ext4/xattr.c
--- linux-2.6.30.3-orig/fs/ext4/xattr.c    2009-07-25 03:17:51.000000000 +0530
+++ linux-2.6.30.3-fix/fs/ext4/xattr.c    2009-08-07 20:27:40.907412651 +0530
@@ -698,7 +698,7 @@
 #define header(x) ((struct ext4_xattr_header *)(x))

     if (i->value && i->value_len > sb->s_blocksize)
-        return -ENOSPC;
+        return -E2BIG;
     if (s->base) {
         ce = mb_cache_entry_get(ext4_xattr_cache, bs->bh->b_bdev,
                     bs->bh->b_blocknr);
====Patch ends

Ran test_xattr.py on the kernel with above fix, it terminates with OSError 7.

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[Bug 12793] ext4 gives wrong errno with too long extended attribute values

[bugzilla-daemon]

http://bugzilla.kernel.org/show_bug.cgi?id=12793


Theodore Tso <tytso@mit.edu> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tytso@mit.edu
         Regression|---                         |No




--- Comment #2 from Theodore Tso <tytso@mit.edu>  2009-08-11 02:58:18 ---
I'm not convinced this change to use E2BIG instead of ENOSPC is always the
right thing.   Consider the wording of E2BIG: "The value of the given attribute
is too large, IT EXCEEDS THE MAXIMUM ALLOWABLE SIZE OF AN ATTRIBUTE VALUE".  In
other words E2BIG implies that a request was made to create an attribute where
the size exceeded some static value.

So if we pass in a request to create an attribute which is 2MB, E2BIG makes
sense.  On the other hand, if the EA block is almost full, a request to create
an attribute value which is 2 bytes long could result in an error --- and in
that case, ENOSPC makes a lot more sense that E2BIG.

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[Bug 12793] ext4 gives wrong errno with too long extended attribute values

[bugzilla-daemon]

https://bugzilla.kernel.org/show_bug.cgi?id=12793


Alan <alan@lxorguk.ukuu.org.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |alan@lxorguk.ukuu.org.uk
         Resolution|                            |OBSOLETE




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[Bug 12793] ext4 gives wrong errno with too long extended attribute values

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https://bugzilla.kernel.org/show_bug.cgi?id=12793


Alan <alan@lxorguk.ukuu.org.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |CLOSED




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