> Am 23.02.2014 um 07:03 schrieb Hin-Tak Leung <htl10@xxxxxxxxxxxxxxxxxxxxx>:
>
> ------------------------------
> On Sun, Feb 23, 2014 5:33 AM GMT Sergei Antonov wrote:
>
>>> --- a/fs/hfsplus/hfsplus_fs.h
>>> +++ b/fs/hfsplus/hfsplus_fs.h
>>> ...
>>> @@ -166,6 +167,11 @@ struct hfsplus_sb_info {
>>> u32 total_blocks;
>>> u32 data_clump_blocks, rsrc_clump_blocks;
>>>
>>> + /* immutable data on the placement of the journal (if there is one) */
>>> + u64 journal_offset; /* relative to volume start */
>>> + u64 journal_size; /* relative to volume start */
>>> + bool journal_swab; /* need swap bytes in journal */
>>> +
>>> /* mutable data from the volume header, protected by alloc_mutex */
>>> u32 free_blocks;
>>> struct mutex alloc_mutex;
>>> ...
>>>
>>> --- a/fs/hfsplus/hfsplus_raw.h
>>> +++ b/fs/hfsplus/hfsplus_raw.h
>>> @@ -105,7 +105,7 @@ struct hfsplus_vh {
>>> __be16 version;
>>> __be32 attributes;
>>> __be32 last_mount_vers;
>>> - u32 reserved;
>>> + __be32 jrnl_info_block;
>>>
>>> __be32 create_date;
>>> __be32 modify_date;
>>> @@ -145,6 +145,69 @@ struct hfsplus_vh {
>>> #define HFSPLUS_VOL_JOURNALED (1 < 13)
>>> #define HFSPLUS_VOL_SOFTLOCK (1 < 15)
>>>
>>> +/* Journal info */
>>> +struct hfs_jrnl_info {
>>> + __be32 flags;
>>> + u32 unused[8];
>>> + __be64 journal_offset; /* Misaligned! relative to volume start */
>>> + __be64 journal_size; /* Misaligned! relative to volume start */
>>> +} __packed;
>>> +
>>> ...
>>>
>>> Storing journal_offset and journal_size in two places seems redundant
>>> - the journal info block is part of the volume header struct, which is accessible
>>> from the superblock struct.
>>
>> It is not in volume header. Only its block number is in header.
>
> Hmm, would be make sense to hook them up? seems a bit strange
> to have a smaller loose-hanging struct which is 2/3 of the superblock addition.
The structure has misaligned fields. It is only good for reading values through special misalignment-safe functions once. Temporal structure on a way to journal.
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