Re: [PATCH v7 05/19] xfs: Factor out new helper functions xfs_attr_rmtval_set

Chandan Rajendra
2020-02-25T12:50:50Z

On Sunday, February 23, 2020 7:35 AM Allison Collins wrote:
> Break xfs_attr_rmtval_set into two helper functions xfs_attr_rmt_find_hole
> and xfs_attr_rmtval_set_value. xfs_attr_rmtval_set rolls the transaction between the
> helpers, but delayed operations cannot. We will use the helpers later when
> constructing new delayed attribute routines.

I don't see any logical errors.

Reviewed-by: Chandan Rajendra <chandanrlinux@gmail.com>

>
> Signed-off-by: Allison Collins <allison.henderson@oracle.com>
> Reviewed-by: Brian Foster <bfoster@redhat.com>
> Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
> fs/xfs/libxfs/xfs_attr_remote.c | 149 +++++++++++++++++++++++++---------------
> 1 file changed, 92 insertions(+), 57 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_attr_remote.c b/fs/xfs/libxfs/xfs_attr_remote.c
> index df8aca5..d1eee24 100644
> --- a/fs/xfs/libxfs/xfs_attr_remote.c
> +++ b/fs/xfs/libxfs/xfs_attr_remote.c
> @@ -440,32 +440,23 @@ xfs_attr_rmtval_get(
> }
>
> /*
> - * Write the value associated with an attribute into the out-of-line buffer
> - * that we have defined for it.
> + * Find a "hole" in the attribute address space large enough for us to drop the
> + * new attribute's value into
> */
> -int
> -xfs_attr_rmtval_set(
> +STATIC int
> +xfs_attr_rmt_find_hole(
> struct xfs_da_args *args)
> {
> struct xfs_inode *dp = args->dp;
> struct xfs_mount *mp = dp->i_mount;
> - struct xfs_bmbt_irec map;
> - xfs_dablk_t lblkno;
> - xfs_fileoff_t lfileoff = 0;
> - uint8_t *src = args->value;
> - int blkcnt;
> - int valuelen;
> - int nmap;
> int error;
> - int offset = 0;
> -
> - trace_xfs_attr_rmtval_set(args);
> + int blkcnt;
> + xfs_fileoff_t lfileoff = 0;
>
> /*
> - * Find a "hole" in the attribute address space large enough for
> - * us to drop the new attribute's value into. Because CRC enable
> - * attributes have headers, we can't just do a straight byte to FSB
> - * conversion and have to take the header space into account.
> + * Because CRC enable attributes have headers, we can't just do a
> + * straight byte to FSB conversion and have to take the header space
> + * into account.
> */
> blkcnt = xfs_attr3_rmt_blocks(mp, args->rmtvaluelen);
> error = xfs_bmap_first_unused(args->trans, args->dp, blkcnt, &lfileoff,
> @@ -473,48 +464,26 @@ xfs_attr_rmtval_set(
> if (error)
> return error;
>
> - args->rmtblkno = lblkno = (xfs_dablk_t)lfileoff;
> + args->rmtblkno = (xfs_dablk_t)lfileoff;
> args->rmtblkcnt = blkcnt;
>
> - /*
> - * Roll through the "value", allocating blocks on disk as required.
> - */
> - while (blkcnt > 0) {
> - /*
> - * Allocate a single extent, up to the size of the value.
> - *
> - * Note that we have to consider this a data allocation as we
> - * write the remote attribute without logging the contents.
> - * Hence we must ensure that we aren't using blocks that are on
> - * the busy list so that we don't overwrite blocks which have
> - * recently been freed but their transactions are not yet
> - * committed to disk. If we overwrite the contents of a busy
> - * extent and then crash then the block may not contain the
> - * correct metadata after log recovery occurs.
> - */
> - nmap = 1;
> - error = xfs_bmapi_write(args->trans, dp, (xfs_fileoff_t)lblkno,
> - blkcnt, XFS_BMAPI_ATTRFORK, args->total, &map,
> - &nmap);
> - if (error)
> - return error;
> - error = xfs_defer_finish(&args->trans);
> - if (error)
> - return error;
> -
> - ASSERT(nmap == 1);
> - ASSERT((map.br_startblock != DELAYSTARTBLOCK) &&
> - (map.br_startblock != HOLESTARTBLOCK));
> - lblkno += map.br_blockcount;
> - blkcnt -= map.br_blockcount;
> + return 0;
> +}
>
> - /*
> - * Start the next trans in the chain.
> - */
> - error = xfs_trans_roll_inode(&args->trans, dp);
> - if (error)
> - return error;
> - }
> +STATIC int
> +xfs_attr_rmtval_set_value(
> + struct xfs_da_args *args)
> +{
> + struct xfs_inode *dp = args->dp;
> + struct xfs_mount *mp = dp->i_mount;
> + struct xfs_bmbt_irec map;
> + xfs_dablk_t lblkno;
> + uint8_t *src = args->value;
> + int blkcnt;
> + int valuelen;
> + int nmap;
> + int error;
> + int offset = 0;
>
> /*
> * Roll through the "value", copying the attribute value to the
> @@ -595,6 +564,72 @@ xfs_attr_rmtval_stale(
> }
>
> /*
> + * Write the value associated with an attribute into the out-of-line buffer
> + * that we have defined for it.
> + */
> +int
> +xfs_attr_rmtval_set(
> + struct xfs_da_args *args)
> +{
> + struct xfs_inode *dp = args->dp;
> + struct xfs_bmbt_irec map;
> + xfs_dablk_t lblkno;
> + int blkcnt;
> + int nmap;
> + int error;
> +
> + trace_xfs_attr_rmtval_set(args);
> +
> + error = xfs_attr_rmt_find_hole(args);
> + if (error)
> + return error;
> +
> + blkcnt = args->rmtblkcnt;
> + lblkno = (xfs_dablk_t)args->rmtblkno;
> + /*
> + * Roll through the "value", allocating blocks on disk as required.
> + */
> + while (blkcnt > 0) {
> + /*
> + * Allocate a single extent, up to the size of the value.
> + *
> + * Note that we have to consider this a data allocation as we
> + * write the remote attribute without logging the contents.
> + * Hence we must ensure that we aren't using blocks that are on
> + * the busy list so that we don't overwrite blocks which have
> + * recently been freed but their transactions are not yet
> + * committed to disk. If we overwrite the contents of a busy
> + * extent and then crash then the block may not contain the
> + * correct metadata after log recovery occurs.
> + */
> + nmap = 1;
> + error = xfs_bmapi_write(args->trans, dp, (xfs_fileoff_t)lblkno,
> + blkcnt, XFS_BMAPI_ATTRFORK, args->total, &map,
> + &nmap);
> + if (error)
> + return error;
> + error = xfs_defer_finish(&args->trans);
> + if (error)
> + return error;
> +
> + ASSERT(nmap == 1);
> + ASSERT((map.br_startblock != DELAYSTARTBLOCK) &&
> + (map.br_startblock != HOLESTARTBLOCK));
> + lblkno += map.br_blockcount;
> + blkcnt -= map.br_blockcount;
> +
> + /*
> + * Start the next trans in the chain.
> + */
> + error = xfs_trans_roll_inode(&args->trans, dp);
> + if (error)
> + return error;
> + }
> +
> + return xfs_attr_rmtval_set_value(args);
> +}
> +
> +/*
> * Remove the value associated with an attribute by deleting the
> * out-of-line buffer that it is stored on.
> */
>

--
chandan