WARNING: This server is unstable and will be retired in the next days.
If you want to keep this forum available, please request immediately a migration
on the Nabble Support forum.
Forums that don't receive any migration request will be deleted forever.
I am already using FSB format, i am using this format for sparsing the absolute block number,
as we know extent is 128 bit in size and uses the following packed layout:
LSB... bit 0-20 gives # blocks
bits 21 to 72 (52) gives absolute number
bits 72 to 126 (54) gives logical file block offset
the value i am getting in absolute no. is in FSB and after multiplying with no. of sectors in FS block i am trying to jump that value (pointer location). But only in 0th AG i am able to get the data.Afterwards i am not able to reach the data in next AGs.
I also read in document that "sb_agblklog"--> This value is used to generate inode numbers and absolute block numbers defined in extent maps.
How i can use this value in interprating the absolute block number?
Is the above sparsing method is right or there is any other calculation? Please guide me.
David Chinner wrote:
On Thu, Jun 21, 2007 at 11:23:35PM -0700, Sandy1 wrote:
> I am Using SuSe 10.0 with Xfs file system. I am working on a File system
> based project. During the initial research in On disk layout of File system
> , i found data pointer problem. I was not able to get the data location as
> per pointed by "absolute block no." in "xfs_bmbt_rec" extent pointers.
The xfs_bmbt_rec holds the address in FSB format, not DADDR format.
> When i create any file in 0th (zero`th) AG in that case i am able to reach
> on proper location by using "absolute block no." pointer.
> But when i create any file in 1st or in 2nd AG and so on. I never got the
> file data at the location pointed by "absolute block no.". I always found
> the file data before the the pointed address.
FSB notation is sparse representation.
> I am not getting any value in Superblock that tells me about difference in
> pointer location with actual data.
> This value always becomes multiple of the AG number.
> Please help to get out from this problem.
> Is there any other calculation for finding the data locations.
man xfs_db. Search for "convert".
SGI Australian Software Group