Re: [PATCH] Fix journal detection on HFS+.

["Warren Turkal" <wt@penguintechs.org>]

The kernel was mounting an HFS+ FS ro if the volume header indicated
that it had a journal and the journal info block was 0. The kernel
should just treat the volume as not having a journal in that case.

wt

On Wed, Nov 19, 2008 at 2:51 PM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> On Tue, 11 Nov 2008 12:56:47 -0800
> Warren Turkal <wt@penguintechs.org> wrote:
>
>> The code was unconditionally assumming that the volume had a jounal if the
>> jounal attribute was set in the volume header. However, the volume also has to
>> have a non-zero journal info block to actually have a journal.
>
> OK, but so what?
>
> Presumably there is some situation in which this is causing you a
> problem, but what is that situation, and what was the kernel's
> behaviour in that situation?
>
>> Signed-off-by: Warren Turkal <wt@penguintechs.org>
>> ---
>>  fs/hfsplus/super.c |   11 +++++++++--
>>  1 files changed, 9 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/hfsplus/super.c b/fs/hfsplus/super.c
>> index eb74531..128101b 100644
>> --- a/fs/hfsplus/super.c
>> +++ b/fs/hfsplus/super.c
>> @@ -17,9 +17,16 @@
>>
>>  static struct inode *hfsplus_alloc_inode(struct super_block *sb);
>>  static void hfsplus_destroy_inode(struct inode *inode);
>> +static bool hfsplus_vol_has_journal(struct hfsplus_vh *vhdr);
>>
>>  #include "hfsplus_fs.h"
>>
>> +static bool hfsplus_vol_has_journal(struct hfsplus_vh *vhdr)
>> +{
>> +     return (vhdr->attributes & cpu_to_be32(HFSPLUS_VOL_JOURNALED) &&
>> +                             vhdr->journal_info_block);
>> +}
>> +
>>  struct inode *hfsplus_iget(struct super_block *sb, unsigned long ino)
>>  {
>>       struct hfs_find_data fd;
>> @@ -260,7 +267,7 @@ static int hfsplus_remount(struct super_block *sb, int *flags, char *data)
>>                       printk(KERN_WARNING "hfs: filesystem is marked locked, leaving read-only.\n");
>>                       sb->s_flags |= MS_RDONLY;
>>                       *flags |= MS_RDONLY;
>> -             } else if (vhdr->attributes & cpu_to_be32(HFSPLUS_VOL_JOURNALED)) {
>> +             } else if (hfsplus_vol_has_journal(vhdr)) {
>>                       printk(KERN_WARNING "hfs: filesystem is marked journaled, leaving read-only.\n");
>>                       sb->s_flags |= MS_RDONLY;
>>                       *flags |= MS_RDONLY;
>> @@ -356,7 +363,7 @@ static int hfsplus_fill_super(struct super_block *sb, void *data, int silent)
>>       } else if (vhdr->attributes & cpu_to_be32(HFSPLUS_VOL_SOFTLOCK)) {
>>               printk(KERN_WARNING "hfs: Filesystem is marked locked, mounting read-only.\n");
>>               sb->s_flags |= MS_RDONLY;
>> -     } else if ((vhdr->attributes & cpu_to_be32(HFSPLUS_VOL_JOURNALED)) && !(sb->s_flags & MS_RDONLY)) {
>> +     } else if (hfsplus_vol_has_journal(vhdr) && !(sb->s_flags & MS_RDONLY)) {
>>               printk(KERN_WARNING "hfs: write access to a journaled filesystem is not supported, "
>>                      "use the force option at your own risk, mounting read-only.\n");
>>               sb->s_flags |= MS_RDONLY;
>
> The patch itself looks OK to me.
>