[Cluster-devel] [PATCH 06/19] libgfs2: Add functions for finding free extents

[Steven Whitehouse <swhiteho@redhat.com>]

Hi,

On 03/09/14 13:13, Andrew Price wrote:
> On 03/09/14 11:17, Steven Whitehouse wrote:
>> Hi,
>>
>> You shouldn't need this for allocation in mkfs since you already know
>> where the free extents are, so no need to be reading the bitmaps to find
>> that out,
>>
>> Steve.
>
> Well, that's true, but I'd like to use generic file allocation 
> functions where possible and I wanted to make sure the new functions 
> were able to allocate extents. I'd like to keep these changes in 
> libgfs2 anyway because they'll be useful for future work in other 
> tools, so how about an additional patch like the one below?
>
> Andy
>
That may be ok, depending on the context. I was expecting to see a two 
stage process of calculating how many blocks are required, and then 
figuring out how to divide the blocks between the rgrps (i.e. fixing the 
location) as a second stage,

Steve.

> diff --git a/gfs2/libgfs2/fs_ops.c b/gfs2/libgfs2/fs_ops.c
> index 9c9cc82..b84b7f4 100644
> --- a/gfs2/libgfs2/fs_ops.c
> +++ b/gfs2/libgfs2/fs_ops.c
> @@ -296,7 +296,9 @@ uint64_t lgfs2_space_for_data(const struct 
> gfs2_sbd *sdp, const unsigned bsize,
>   * Allocate an extent for a file in a resource group's bitmaps.
>   * rg: The resource group in which to allocate the extent
>   * di_size: The size of the file in bytes
> - * ip: A pointer to the inode structure, whose fields will be set 
> appropriately
> + * ip: A pointer to the inode structure, whose fields will be set 
> appropriately.
> + *     If ip->i_di.di_num.no_addr is not 0, the extent search will be 
> skipped and
> + *     the file allocated from that address.
>   * flags: GFS2_DIF_* flags
>   * mode: File mode flags, see creat(2)
>   * Returns 0 on success with the contents of ip set accordingly, or 
> non-zero
> @@ -310,11 +312,13 @@ int lgfs2_file_alloc(lgfs2_rgrp_t rg, uint64_t 
> di_size, struct gfs2_inode *ip, u
>      struct gfs2_sbd *sdp = rg->rgrps->sdp;
>      struct lgfs2_rbm rbm = { .rgd = rg, .offset = 0, .bii = 0 };
>      uint32_t blocks = lgfs2_space_for_data(sdp, sdp->bsize, di_size);
> -    int err;
>
> -    err = lgfs2_rbm_find(&rbm, GFS2_BLKST_FREE, &blocks);
> -    if (err != 0)
> -        return err;
> +    if (ip->i_di.di_num.no_addr != 0) {
> +        if (lgfs2_rbm_from_block(&rbm, ip->i_di.di_num.no_addr) != 0)
> +            return 1;
> +    } else if (lgfs2_rbm_find(&rbm, GFS2_BLKST_FREE, &blocks) != 0) {
> +        return 1;
> +    }
>
>      extlen = lgfs2_alloc_extent(&rbm, GFS2_BLKST_DINODE, blocks);
>      if (extlen < blocks) {
> diff --git a/gfs2/libgfs2/rgrp.c b/gfs2/libgfs2/rgrp.c
> index f57ae3a..0d0f000 100644
> --- a/gfs2/libgfs2/rgrp.c
> +++ b/gfs2/libgfs2/rgrp.c
> @@ -643,7 +643,7 @@ lgfs2_rgrp_t lgfs2_rgrp_last(lgfs2_rgrps_t rgs)
>   *
>   * Returns: 0 on success, or non-zero with errno set
>   */
> -static int lgfs2_rbm_from_block(struct lgfs2_rbm *rbm, uint64_t block)
> +int lgfs2_rbm_from_block(struct lgfs2_rbm *rbm, uint64_t block)
>  {
>      uint64_t rblock = block - rbm->rgd->ri.ri_data0;
>      struct gfs2_sbd *sdp = rbm_bi(rbm)->bi_bh->sdp;
> diff --git a/gfs2/libgfs2/rgrp.h b/gfs2/libgfs2/rgrp.h
> index bd89289..fd442b1 100644
> --- a/gfs2/libgfs2/rgrp.h
> +++ b/gfs2/libgfs2/rgrp.h
> @@ -44,6 +44,7 @@ static inline int lgfs2_rbm_eq(const struct 
> lgfs2_rbm *rbm1, const struct lgfs2_
>              (rbm1->offset == rbm2->offset);
>  }
>
> +extern int lgfs2_rbm_from_block(struct lgfs2_rbm *rbm, uint64_t block);
>  extern int lgfs2_rbm_find(struct lgfs2_rbm *rbm, uint8_t state, 
> uint32_t *minext);
>  extern unsigned lgfs2_alloc_extent(const struct lgfs2_rbm *rbm, int 
> state, const unsigned elen);
>
> diff --git a/gfs2/mkfs/main_mkfs.c b/gfs2/mkfs/main_mkfs.c
> index 530383d..e927d82 100644
> --- a/gfs2/mkfs/main_mkfs.c
> +++ b/gfs2/mkfs/main_mkfs.c
> @@ -694,6 +694,8 @@ static int place_journals(struct gfs2_sbd *sdp, 
> lgfs2_rgrps_t rgs, struct mkfs_o
>              perror(_("Failed to allocate space for bitmap buffer"));
>              return result;
>          }
> +        /* Allocate at the beginning of the rgrp, bypassing extent 
> search */
> +        in.i_di.di_num.no_addr = lgfs2_rgrp_index(rg)->ri_data0;
>          /* In order to keep writes sequential here, we have to allocate
>             the journal, then write the rgrp header (which is now in its
>             final form) and then write the journal out */
>