2012/12/12, Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx>:
> 2012-12-12 (수), 00:10 +0900, Namjae Jeon:
>> From: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
>>
>> Test Case:
>> [NFS Client]
>> ls -lR .
>>
>> [NFS Server]
>> while [ 1 ]
>> do
>> echo 3 > /proc/sys/vm/drop_caches
>> done
>>
>> Error on NFS Client: "No such file or directory"
>>
>> When cache is dropped at the server, it results in lookup failure at the
>> NFS client due to non-connection with the parent. The default path is it
>> initiates a lookup by calculating the hash value for the name, even
>> though
>> the hash values stored on the disk for "." and ".." is maintained as
>> zero,
>> which results in failure from find_in_block due to not matching HASH
>> values.
>> Fix up, by using the correct hashing values for these entries and
>> then initiating lookup request.
>>
>> Signed-off-by: Namjae Jeon <namjae.jeon@xxxxxxxxxxx>
>> Signed-off-by: Amit Sahrawat <a.sahrawat@xxxxxxxxxxx>
>> ---
>> fs/f2fs/dir.c | 5 +++--
>> 1 file changed, 3 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
>> index b4e24f3..6cf39db 100644
>> --- a/fs/f2fs/dir.c
>> +++ b/fs/f2fs/dir.c
>> @@ -184,7 +184,7 @@ struct f2fs_dir_entry *f2fs_find_entry(struct inode
>> *dir,
>> int namelen = child->len;
>> unsigned long npages = dir_blocks(dir);
>> struct f2fs_dir_entry *de = NULL;
>> - f2fs_hash_t name_hash;
>> + f2fs_hash_t name_hash = 0;
>> unsigned int max_depth;
>> unsigned int level;
>>
>> @@ -193,7 +193,8 @@ struct f2fs_dir_entry *f2fs_find_entry(struct inode
>> *dir,
>>
>> *res_page = NULL;
>>
>> - name_hash = f2fs_dentry_hash(name, namelen);
>> + if (strcmp(name, ".") && (strcmp(name, "..")))
>> + name_hash = f2fs_dentry_hash(name, namelen);
>
> Got it.
> For code consistency, could you rewrite the patch like below?
> Thanks,
Sure, I will resend the patch at tonight.
Thanks!
>
> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> index b4e24f3..e1f66df 100644
> --- a/fs/f2fs/dir.c
> +++ b/fs/f2fs/dir.c
> @@ -540,13 +540,13 @@ int f2fs_make_empty(struct inode *inode, struct
> inode *parent)
>
> de = &dentry_blk->dentry[0];
> de->name_len = cpu_to_le16(1);
> - de->hash_code = 0;
> + de->hash_code = f2fs_dentry_hash(".", 1);
> de->ino = cpu_to_le32(inode->i_ino);
> memcpy(dentry_blk->filename[0], ".", 1);
> set_de_type(de, inode);
>
> de = &dentry_blk->dentry[1];
> - de->hash_code = 0;
> + de->hash_code = f2fs_dentry_hash("..", 2);
> de->name_len = cpu_to_le16(2);
> de->ino = cpu_to_le32(parent->i_ino);
> memcpy(dentry_blk->filename[1], "..", 2);
> diff --git a/fs/f2fs/hash.c b/fs/f2fs/hash.c
> index a60f042..30ca4a2 100644
> --- a/fs/f2fs/hash.c
> +++ b/fs/f2fs/hash.c
> @@ -76,6 +76,10 @@ f2fs_hash_t f2fs_dentry_hash(const char *name, int
> len)
> const char *p;
> __u32 in[8], buf[4];
>
> + /* dot and dotdot dentries should have zero-value hash code */
> + if (!memcmp(name, ".", 1) || !memcmp(name, "..", 2))
> + return 0;
> +
> /* Initialize the default seed for the hash checksum functions */
> buf[0] = 0x67452301;
> buf[1] = 0xefcdab89;
> --
> 1.8.0.1.250.gb7973fb
>
>
>
> --
> Jaegeuk Kim
> Samsung
>
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