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ext4: return 32/64-bit dir name hash according to usage type

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Traditionally ext2/3/4 has returned a 32-bit hash value from llseek()
to appease NFSv2, which can only handle a 32-bit cookie for seekdir()
and telldir().  However, this causes problems if there are 32-bit hash
collisions, since the NFSv2 server can get stuck resending the same
entries from the directory repeatedly.

Allow ext4 to return a full 64-bit hash (both major and minor) for
telldir to decrease the chance of hash collisions.  This still needs
integration on the NFS side.

Patch-updated-by: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
(blame me if something is not correct)

Signed-off-by: Fan Yong <yong.fan@whamcloud.com>
Signed-off-by: Andreas Dilger <adilger@whamcloud.com>
Signed-off-by: Bernd Schubert <bernd.schubert@itwm.fraunhofer.de>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Fan Yong
2012-03-18 22:44:40 -04:00
committed by Theodore Ts'o
parent 6a8a13e038
commit d1f5273e9a
3 changed files with 176 additions and 48 deletions
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6
fs/ext4/ext4.h
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@@ -1612,7 +1612,11 @@ struct dx_hash_info
u32 *seed;
};
#define EXT4_HTREE_EOF 0x7fffffff
/* 32 and 64 bit signed EOF for dx directories */
#define EXT4_HTREE_EOF_32BIT ((1UL << (32 - 1)) - 1)
#define EXT4_HTREE_EOF_64BIT ((1ULL << (64 - 1)) - 1)
/*
* Control parameters used by ext4_htree_next_block