On Fri, Dec 04, 2020 at 12:10:27AM +0800, Gao Xiang wrote:
> From: Dave Chinner <dchinner@xxxxxxxxxx>
>
> This patch explicitly separates free inode chunk allocation and
> inode allocation into two individual high level operations.
>
> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
> Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxx>
FWIW I thought about doing some similar things with the xfs_dir_ialloc
in the metadata directory tree patchset, so this makes sense to me (and
will probably simplify things) so:
Reviewed-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
--D
> ---
> fs/xfs/libxfs/xfs_ialloc.c | 59 +++++++++++++++++---------------------
> fs/xfs/libxfs/xfs_ialloc.h | 20 +++++++++----
> fs/xfs/xfs_inode.c | 19 ++++++++----
> 3 files changed, 55 insertions(+), 43 deletions(-)
>
> diff --git a/fs/xfs/libxfs/xfs_ialloc.c b/fs/xfs/libxfs/xfs_ialloc.c
> index d2d7378abf49..597629353d4d 100644
> --- a/fs/xfs/libxfs/xfs_ialloc.c
> +++ b/fs/xfs/libxfs/xfs_ialloc.c
> @@ -1570,7 +1570,7 @@ xfs_dialloc_ag_update_inobt(
> * The caller selected an AG for us, and made sure that free inodes are
> * available.
> */
> -STATIC int
> +int
> xfs_dialloc_ag(
> struct xfs_trans *tp,
> struct xfs_buf *agbp,
> @@ -1728,21 +1728,22 @@ xfs_dialloc_roll(
> }
>
> /*
> - * Allocate an inode on disk.
> + * Select and prepare an AG for inode allocation.
> *
> - * Mode is used to tell whether the new inode will need space, and whether it
> - * is a directory.
> + * Mode is used to tell whether the new inode is a directory and hence where to
> + * locate it.
> *
> - * Once we successfully pick an inode its number is returned and the on-disk
> - * data structures are updated. The inode itself is not read in, since doing so
> - * would break ordering constraints with xfs_reclaim.
> + * This function will ensure that the selected AG has free inodes available to
> + * allocate from. The selected AGI will be returned locked to the caller, and it
> + * will allocate more free inodes if required. If no free inodes are found or
> + * can be allocated, no AGI will be returned.
> */
> int
> -xfs_dialloc(
> +xfs_dialloc_select_ag(
> struct xfs_trans **tpp,
> xfs_ino_t parent,
> umode_t mode,
> - xfs_ino_t *inop)
> + struct xfs_buf **IO_agbp)
> {
> struct xfs_mount *mp = (*tpp)->t_mountp;
> struct xfs_buf *agbp;
> @@ -1755,15 +1756,15 @@ xfs_dialloc(
> struct xfs_ino_geometry *igeo = M_IGEO(mp);
> bool okalloc = true;
>
> + *IO_agbp = NULL;
> +
> /*
> * We do not have an agbp, so select an initial allocation
> * group for inode allocation.
> */
> start_agno = xfs_ialloc_ag_select(*tpp, parent, mode);
> - if (start_agno == NULLAGNUMBER) {
> - *inop = NULLFSINO;
> + if (start_agno == NULLAGNUMBER)
> return 0;
> - }
>
> /*
> * If we have already hit the ceiling of inode blocks then clear
> @@ -1796,7 +1797,7 @@ xfs_dialloc(
> if (!pag->pagi_init) {
> error = xfs_ialloc_pagi_init(mp, *tpp, agno);
> if (error)
> - goto out_error;
> + break;
> }
>
> /*
> @@ -1811,11 +1812,12 @@ xfs_dialloc(
> */
> error = xfs_ialloc_read_agi(mp, *tpp, agno, &agbp);
> if (error)
> - goto out_error;
> + break;
>
> if (pag->pagi_freecount) {
> xfs_perag_put(pag);
> - goto out_alloc;
> + *IO_agbp = agbp;
> + return 0;
> }
>
> if (!okalloc)
> @@ -1826,19 +1828,17 @@ xfs_dialloc(
> if (error) {
> xfs_trans_brelse(*tpp, agbp);
>
> - if (error != -ENOSPC)
> - goto out_error;
> -
> - xfs_perag_put(pag);
> - *inop = NULLFSINO;
> - return 0;
> + if (error == -ENOSPC)
> + error = 0;
> + break;
> }
>
> if (ialloced) {
> /*
> - * We successfully allocated some inodes, roll the
> - * transaction so they can allocate one of the free
> - * inodes we just prepared for them.
> + * We successfully allocated some inodes, so roll the
> + * transaction and return the locked AGI buffer to the
> + * caller so they can allocate one of the free inodes we
> + * just prepared for them.
> */
> ASSERT(pag->pagi_freecount > 0);
> xfs_perag_put(pag);
> @@ -1847,8 +1847,8 @@ xfs_dialloc(
> if (error)
> return error;
>
> - *inop = NULLFSINO;
> - goto out_alloc;
> + *IO_agbp = agbp;
> + return 0;
> }
>
> nextag_relse_buffer:
> @@ -1857,15 +1857,10 @@ xfs_dialloc(
> xfs_perag_put(pag);
> if (++agno == mp->m_sb.sb_agcount)
> agno = 0;
> - if (agno == start_agno) {
> - *inop = NULLFSINO;
> + if (agno == start_agno)
> return noroom ? -ENOSPC : 0;
> - }
> }
>
> -out_alloc:
> - return xfs_dialloc_ag(*tpp, agbp, parent, inop);
> -out_error:
> xfs_perag_put(pag);
> return error;
> }
> diff --git a/fs/xfs/libxfs/xfs_ialloc.h b/fs/xfs/libxfs/xfs_ialloc.h
> index 13810ffe4af9..3511086a7ae1 100644
> --- a/fs/xfs/libxfs/xfs_ialloc.h
> +++ b/fs/xfs/libxfs/xfs_ialloc.h
> @@ -37,16 +37,26 @@ xfs_make_iptr(struct xfs_mount *mp, struct xfs_buf *b, int o)
> * Mode is used to tell whether the new inode will need space, and whether
> * it is a directory.
> *
> - * Once we successfully pick an inode its number is returned and the
> - * on-disk data structures are updated. The inode itself is not read
> - * in, since doing so would break ordering constraints with xfs_reclaim.
> + * There are two phases to inode allocation: selecting an AG and ensuring
> + * that it contains free inodes, followed by allocating one of the free
> + * inodes. xfs_dialloc_select_ag() does the former and returns a locked AGI
> + * to the caller, ensuring that followup call to xfs_dialloc_ag() will
> + * have free inodes to allocate from. xfs_dialloc_ag() will return the inode
> + * number of the free inode we allocated.
> */
> int /* error */
> -xfs_dialloc(
> +xfs_dialloc_select_ag(
> struct xfs_trans **tpp, /* double pointer of transaction */
> xfs_ino_t parent, /* parent inode (directory) */
> umode_t mode, /* mode bits for new inode */
> - xfs_ino_t *inop); /* inode number allocated */
> + struct xfs_buf **IO_agbp);
> +
> +int
> +xfs_dialloc_ag(
> + struct xfs_trans *tp,
> + struct xfs_buf *agbp,
> + xfs_ino_t parent,
> + xfs_ino_t *inop);
>
> /*
> * Free disk inode. Carefully avoids touching the incore inode, all
> diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> index c039fc56b396..d0ae0d6ee892 100644
> --- a/fs/xfs/xfs_inode.c
> +++ b/fs/xfs/xfs_inode.c
> @@ -908,10 +908,11 @@ xfs_dir_ialloc(
> xfs_inode_t **ipp) /* pointer to inode; it will be
> locked. */
> {
> - xfs_inode_t *ip;
> - xfs_ino_t pino = dp ? dp->i_ino : 0;
> - xfs_ino_t ino;
> - int error;
> + struct xfs_buf *agibp;
> + struct xfs_inode *ip;
> + xfs_ino_t pino = dp ? dp->i_ino : 0;
> + xfs_ino_t ino;
> + int error;
>
> ASSERT((*tpp)->t_flags & XFS_TRANS_PERM_LOG_RES);
> *ipp = NULL;
> @@ -927,13 +928,19 @@ xfs_dir_ialloc(
> * commit so that no other process can steal the inode(s) that we've
> * just allocated.
> */
> - error = xfs_dialloc(tpp, pino, mode, &ino);
> + error = xfs_dialloc_select_ag(tpp, pino, mode, &agibp);
> if (error)
> return error;
>
> - if (ino == NULLFSINO)
> + if (!agibp)
> return -ENOSPC;
>
> + /* Allocate an inode from the selected AG */
> + error = xfs_dialloc_ag(*tpp, agibp, pino, &ino);
> + if (error)
> + return error;
> + ASSERT(ino != NULLFSINO);
> +
> /* Initialise the newly allocated inode. */
> ip = xfs_ialloc(*tpp, dp, ino, mode, nlink, rdev, prid);
> if (IS_ERR(ip))
> --
> 2.18.4
>
