[PATCH v4 4/4] Documentation: update nfs option in filesystem/vfat.txt

[PATCH v4 4/4] Documentation: update nfs option in filesystem/vfat.txt

[Namjae Jeon]

From: Namjae Jeon <namjae.jeon@samsung.com>

update nfs option in filesystem/vfat.txt

Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Ravishankar N <ravi.n1@samsung.com>
Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
---
 Documentation/filesystems/vfat.txt |   23 ++++++++++++++++++-----
 1 file changed, 18 insertions(+), 5 deletions(-)

diff --git a/Documentation/filesystems/vfat.txt b/Documentation/filesystems/vfat.txt
index de1e6c4..d62f8e6 100644
--- a/Documentation/filesystems/vfat.txt
+++ b/Documentation/filesystems/vfat.txt
@@ -141,13 +141,26 @@ discard       -- If set, issues discard/TRIM commands to the block
 		 device when blocks are freed. This is useful for SSD devices
 		 and sparse/thinly-provisoned LUNs.
 
-nfs           -- This option maintains an index (cache) of directory
-		 inodes by i_logstart which is used by the nfs-related code to
-		 improve look-ups.
-
-		 Enable this only if you want to export the FAT filesystem
+nfs= stale_rw|nostale_ro
+	      -- Enable this only if you want to export the FAT filesystem
 		 over NFS
 
+		 stale_rw:This option maintains an index (cache) of directory
+		 inodes by i_logstart which is used by the nfs-related code to
+		 improve look-ups.Full file operations (read/write) over NFS is supported
+		 but with cache eviction at NFS server, this could result in ESTALE issues.
+
+		 nostale_ro:This option bases the inode number and filehandle on the on-disk
+		 location of a file in the MS-DOS directory entry.This ensures that ESTALE
+		 will not be returned after a file is evicted from the inode cache. However,
+		 it means that operations such as rename, create and unlink could cause
+		 filehandles that previously pointed at one file to point at a different file,
+		 potentially causing data corruption. For this reason, this option also mounts
+		 the filesystem readonly.
+
+		 To maintain backward compatibility, '-o nfs' is also accepted, defaulting to
+		 stale_rw
+
 <bool>: 0,1,yes,no,true,false
 
 TODO
-- 
1.7.9.5

Re: [PATCH v4 4/4] Documentation: update nfs option in filesystem/vfat.txt

[J. Bruce Fields]

On Sun, Oct 07, 2012 at 04:33:02AM -0400, Namjae Jeon wrote:
> From: Namjae Jeon <namjae.jeon@samsung.com>
> 
> update nfs option in filesystem/vfat.txt
> 
> Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
> Signed-off-by: Ravishankar N <ravi.n1@samsung.com>
> Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
> ---
>  Documentation/filesystems/vfat.txt |   23 ++++++++++++++++++-----
>  1 file changed, 18 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/filesystems/vfat.txt b/Documentation/filesystems/vfat.txt
> index de1e6c4..d62f8e6 100644
> --- a/Documentation/filesystems/vfat.txt
> +++ b/Documentation/filesystems/vfat.txt
> @@ -141,13 +141,26 @@ discard       -- If set, issues discard/TRIM commands to the block
>  		 device when blocks are freed. This is useful for SSD devices
>  		 and sparse/thinly-provisoned LUNs.
>  
> -nfs           -- This option maintains an index (cache) of directory
> -		 inodes by i_logstart which is used by the nfs-related code to
> -		 improve look-ups.
> -
> -		 Enable this only if you want to export the FAT filesystem
> +nfs= stale_rw|nostale_ro
> +	      -- Enable this only if you want to export the FAT filesystem
>  		 over NFS
>  
> +		 stale_rw:This option maintains an index (cache) of directory
> +		 inodes by i_logstart which is used by the nfs-related code to
> +		 improve look-ups.Full file operations (read/write) over NFS is supported
> +		 but with cache eviction at NFS server, this could result in ESTALE issues.
> +
> +		 nostale_ro:This option bases the inode number and filehandle on the on-disk
> +		 location of a file in the MS-DOS directory entry.This ensures that ESTALE
> +		 will not be returned after a file is evicted from the inode cache. However,
> +		 it means that operations such as rename, create and unlink could cause
> +		 filehandles that previously pointed at one file to point at a different file,
> +		 potentially causing data corruption. For this reason, this option also mounts
> +		 the filesystem readonly.
> +
> +		 To maintain backward compatibility, '-o nfs' is also accepted, defaulting to
> +		 stale_rw
> +

The documentation makes more sense to me now, thanks.

--b.

Re: [PATCH v4 4/4] Documentation: update nfs option in filesystem/vfat.txt

[Namjae Jeon]

2012/10/9, J. Bruce Fields <bfields@fieldses.org>:
> On Sun, Oct 07, 2012 at 04:33:02AM -0400, Namjae Jeon wrote:
>> From: Namjae Jeon <namjae.jeon@samsung.com>
>>
>> update nfs option in filesystem/vfat.txt
>>
>> Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
>> Signed-off-by: Ravishankar N <ravi.n1@samsung.com>
>> Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com>
>> ---
>>  Documentation/filesystems/vfat.txt |   23 ++++++++++++++++++-----
>>  1 file changed, 18 insertions(+), 5 deletions(-)
>>
>> diff --git a/Documentation/filesystems/vfat.txt
>> b/Documentation/filesystems/vfat.txt
>> index de1e6c4..d62f8e6 100644
>> --- a/Documentation/filesystems/vfat.txt
>> +++ b/Documentation/filesystems/vfat.txt
>> @@ -141,13 +141,26 @@ discard       -- If set, issues discard/TRIM
>> commands to the block
>>  		 device when blocks are freed. This is useful for SSD devices
>>  		 and sparse/thinly-provisoned LUNs.
>>
>> -nfs           -- This option maintains an index (cache) of directory
>> -		 inodes by i_logstart which is used by the nfs-related code to
>> -		 improve look-ups.
>> -
>> -		 Enable this only if you want to export the FAT filesystem
>> +nfs= stale_rw|nostale_ro
>> +	      -- Enable this only if you want to export the FAT filesystem
>>  		 over NFS
>>
>> +		 stale_rw:This option maintains an index (cache) of directory
>> +		 inodes by i_logstart which is used by the nfs-related code to
>> +		 improve look-ups.Full file operations (read/write) over NFS is
>> supported
>> +		 but with cache eviction at NFS server, this could result in ESTALE
>> issues.
>> +
>> +		 nostale_ro:This option bases the inode number and filehandle on the
>> on-disk
>> +		 location of a file in the MS-DOS directory entry.This ensures that
>> ESTALE
>> +		 will not be returned after a file is evicted from the inode cache.
>> However,
>> +		 it means that operations such as rename, create and unlink could
>> cause
>> +		 filehandles that previously pointed at one file to point at a
>> different file,
>> +		 potentially causing data corruption. For this reason, this option also
>> mounts
>> +		 the filesystem readonly.
>> +
>> +		 To maintain backward compatibility, '-o nfs' is also accepted,
>> defaulting to
>> +		 stale_rw
>> +
>
> The documentation makes more sense to me now, thanks.
Thanks for your review.
>
> --b.
>