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xfs: convert xfs_ialloc_next_ag() to an atomic

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This is currently a spinlock lock protected rotor which can be
implemented with a single atomic operation. Change it to be more
efficient and get rid of the m_agirotor_lock. Noticed while
converting the inode allocation AG selection loop to active perag
references.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
This commit is contained in:
Dave Chinner 2023-02-13 09:14:52 +11:00
parent bab8b79518
commit 20a5eab49d
4 changed files with 4 additions and 20 deletions
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17
fs/xfs/libxfs/xfs_ialloc.c
View File

@ -1576,21 +1576,6 @@ xfs_dialloc_roll(
return error;
}
static xfs_agnumber_t
xfs_ialloc_next_ag(
xfs_mount_t *mp)
{
xfs_agnumber_t agno;
spin_lock(&mp->m_agirotor_lock);
agno = mp->m_agirotor;
if (++mp->m_agirotor >= mp->m_maxagi)
mp->m_agirotor = 0;
spin_unlock(&mp->m_agirotor_lock);
return agno;
}
static bool
xfs_dialloc_good_ag(
struct xfs_perag *pag,
@ -1748,7 +1733,7 @@ xfs_dialloc(
* an AG has enough space for file creation.
*/
if (S_ISDIR(mode))
start_agno = xfs_ialloc_next_ag(mp);
start_agno = atomic_inc_return(&mp->m_agirotor) % mp->m_maxagi;
else {
start_agno = XFS_INO_TO_AGNO(mp, parent);
if (start_agno >= mp->m_maxagi)

3
fs/xfs/libxfs/xfs_sb.c
View File

@ -909,7 +909,8 @@ xfs_sb_mount_common(
struct xfs_mount *mp,
struct xfs_sb *sbp)
{
mp->m_agfrotor = mp->m_agirotor = 0;
mp->m_agfrotor = 0;
atomic_set(&mp->m_agirotor, 0);
mp->m_maxagi = mp->m_sb.sb_agcount;
mp->m_blkbit_log = sbp->sb_blocklog + XFS_NBBYLOG;
mp->m_blkbb_log = sbp->sb_blocklog - BBSHIFT;

3
fs/xfs/xfs_mount.h
View File

@ -210,8 +210,7 @@ typedef struct xfs_mount {
struct xfs_error_cfg m_error_cfg[XFS_ERR_CLASS_MAX][XFS_ERR_ERRNO_MAX];
struct xstats m_stats; /* per-fs stats */
xfs_agnumber_t m_agfrotor; /* last ag where space found */
xfs_agnumber_t m_agirotor; /* last ag dir inode alloced */
spinlock_t m_agirotor_lock;/* .. and lock protecting it */
atomic_t m_agirotor; /* last ag dir inode alloced */
/* Memory shrinker to throttle and reprioritize inodegc */
struct shrinker m_inodegc_shrinker;

1
fs/xfs/xfs_super.c
View File

@ -1922,7 +1922,6 @@ static int xfs_init_fs_context(
return -ENOMEM;
spin_lock_init(&mp->m_sb_lock);
spin_lock_init(&mp->m_agirotor_lock);
INIT_RADIX_TREE(&mp->m_perag_tree, GFP_ATOMIC);
spin_lock_init(&mp->m_perag_lock);
mutex_init(&mp->m_growlock);