On Sat, Dec 20, 2008 at 12:31 AM, Rohit Sharma <imreckless@xxxxxxxxx> wrote: > I am not sure but ext2_alloc_blocks function > in inode.c, allocate blocks for indirect blocks. > You are right, The allocation can be from direct or indirect blocks depending on the availability. What I feel is that you dont need any kind of optimizations for the allocation of all your direct blocks, but surely for indirect blocks. > > > On Sat, Dec 20, 2008 at 12:19 AM, Rohit Sharma <imreckless@xxxxxxxxx> wrote: >> Is there a difference between how ext2 allocates block between >> inode's indirect blocks and data blocks. >> Ofcourse, you surely will have. So, as a part of the block allocation optimization ext2 uses the concepts of goals and reservation windows for its indirect blocks. >> >> On Fri, Dec 19, 2008 at 8:59 PM, Peter Teoh <htmldeveloper@xxxxxxxxx> wrote: >>> On Fri, Dec 19, 2008 at 7:18 PM, Rohit Sharma <imreckless@xxxxxxxxx> wrote: >>>> On Fri, Dec 19, 2008 at 3:05 PM, Peter Teoh <htmldeveloper@xxxxxxxxx> wrote: >>>>> On Fri, Dec 19, 2008 at 3:42 PM, Rohit Sharma <imreckless@xxxxxxxxx> wrote: >>>>>> On Fri, Dec 19, 2008 at 4:09 AM, Jan Kara <jack@xxxxxxx> wrote: >>>>>>>> On Fri, Dec 19, 2008 at 12:12 AM, Rohit Sharma <imreckless@xxxxxxxxx> wrote: >>>>>>>> > How does ext2 allocate blocks for directory. >>>>>>>> > >>>>>>>> > ext2_mkdir calls ext2_make_empty >>>>>>>> > >>>>>>>> > ext2_make_empty calls __ext2_write_begin >>>>>>>> > >>>>>>>> > __ ext2_write_begin calls block_write_begin >>>>>>>> > >>>>>>>> > my query is that how does this function allocates blocks for directories. ?? >>>>>>>> > >>>>>>>> >>>>>>>> Does ext2 uses ext2_get_block to allocate blocks for both files and >>>>>>>> directories. ?? >>>>>>> Yes, exactly. Ext2 (unlike ext3 or ext4) treats directories the same >>>>>>> ways as ordinary files and thus ext2_get_block is used for block >>>>>>> allocation. >>>>>>> >>>>>> >>>>>> Can i modify this function to restrict allocation of blocks >>>>>> to a particular block group ? >>>>>> >>>>>> Like i want that my abc.txt file should be in block group 5 suppose, then >>>>>> what should i do? >>>>>> >>>>> >>>>> I think this can be done. Or is done in the kernel source in several >>>>> ways (indirectly). >>>>> >>>>> 1. ext2_find_goal()-->this will look for the best new block. when >>>>> searching, it will try to find the block to be allocated to follow the >>>>> one last allocated in the file, so as to maintain storage contiguity. >>>>> >>>>> 2. looking into fs/ext2/balloc.c: ext2_try_to_allocate(), there is a >>>>> argument called group_goal, whose purpose is to specify the goal block >>>>> group, and the algorithm will start searching from the group specified >>>>> (look for "start=grp_goal"). Of course, if search is in vain it will >>>>> proceed to other block group, which u don't want ....so may be can >>>>> customize from here. >>>>> >>>>> Not sure if I am right? >>>>> >>>> When we create new file, do we use reservation window to allocate blocks >>>> or we use reservation window every time we need a new data blocks >>>> for file. >>>> >>>> >>> >>> http://lwn.net/Articles/81357/ ===> from here, we deduced that it >>> should be done at every new block request level, and not at the file >>> level. This is because when file level request is initiated, the >>> first thing is see if any existing block can be reused or not, before >>> allocating new block (which then comes with reservation features - to >>> ensure contiguity of datablocks). >>> >>> >>> -- >>> Regards, >>> Peter Teoh >>> >>> Ernest Hemingway - "Never mistake motion for action." >>> >> > > -- > To unsubscribe from this list: send an email with > "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx > Please read the FAQ at http://kernelnewbies.org/FAQ > > -- Regards, Sandeep. "To learn is to change. Education is a process that changes the learner." -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
