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authorDave Chinner <dchinner@redhat.com>2021-03-22 09:52:03 -0700
committerDarrick J. Wong <djwong@kernel.org>2021-03-25 16:47:51 -0700
commite6a688c3323840f3e388ba28fd2db86675b79917 (patch)
treea1413916fb8dc3287c05753d41990229884c0bba /fs/xfs/xfs_inode.h
parentb2c2974b8cdf1eb3ef90ff845eb27b19e2187b7e (diff)
xfs: initialise attr fork on inode create
When we allocate a new inode, we often need to add an attribute to the inode as part of the create. This can happen as a result of needing to add default ACLs or security labels before the inode is made visible to userspace. This is highly inefficient right now. We do the create transaction to allocate the inode, then we do an "add attr fork" transaction to modify the just created empty inode to set the inode fork offset to allow attributes to be stored, then we go and do the attribute creation. This means 3 transactions instead of 1 to allocate an inode, and this greatly increases the load on the CIL commit code, resulting in excessive contention on the CIL spin locks and performance degradation: 18.99% [kernel] [k] __pv_queued_spin_lock_slowpath 3.57% [kernel] [k] do_raw_spin_lock 2.51% [kernel] [k] __raw_callee_save___pv_queued_spin_unlock 2.48% [kernel] [k] memcpy 2.34% [kernel] [k] xfs_log_commit_cil The typical profile resulting from running fsmark on a selinux enabled filesytem is adds this overhead to the create path: - 15.30% xfs_init_security - 15.23% security_inode_init_security - 13.05% xfs_initxattrs - 12.94% xfs_attr_set - 6.75% xfs_bmap_add_attrfork - 5.51% xfs_trans_commit - 5.48% __xfs_trans_commit - 5.35% xfs_log_commit_cil - 3.86% _raw_spin_lock - do_raw_spin_lock __pv_queued_spin_lock_slowpath - 0.70% xfs_trans_alloc 0.52% xfs_trans_reserve - 5.41% xfs_attr_set_args - 5.39% xfs_attr_set_shortform.constprop.0 - 4.46% xfs_trans_commit - 4.46% __xfs_trans_commit - 4.33% xfs_log_commit_cil - 2.74% _raw_spin_lock - do_raw_spin_lock __pv_queued_spin_lock_slowpath 0.60% xfs_inode_item_format 0.90% xfs_attr_try_sf_addname - 1.99% selinux_inode_init_security - 1.02% security_sid_to_context_force - 1.00% security_sid_to_context_core - 0.92% sidtab_entry_to_string - 0.90% sidtab_sid2str_get 0.59% sidtab_sid2str_put.part.0 - 0.82% selinux_determine_inode_label - 0.77% security_transition_sid 0.70% security_compute_sid.part.0 And fsmark creation rate performance drops by ~25%. The key point to note here is that half the additional overhead comes from adding the attribute fork to the newly created inode. That's crazy, considering we can do this same thing at inode create time with a couple of lines of code and no extra overhead. So, if we know we are going to add an attribute immediately after creating the inode, let's just initialise the attribute fork inside the create transaction and chop that whole chunk of code out of the create fast path. This completely removes the performance drop caused by enabling SELinux, and the profile looks like: - 8.99% xfs_init_security - 9.00% security_inode_init_security - 6.43% xfs_initxattrs - 6.37% xfs_attr_set - 5.45% xfs_attr_set_args - 5.42% xfs_attr_set_shortform.constprop.0 - 4.51% xfs_trans_commit - 4.54% __xfs_trans_commit - 4.59% xfs_log_commit_cil - 2.67% _raw_spin_lock - 3.28% do_raw_spin_lock 3.08% __pv_queued_spin_lock_slowpath 0.66% xfs_inode_item_format - 0.90% xfs_attr_try_sf_addname - 0.60% xfs_trans_alloc - 2.35% selinux_inode_init_security - 1.25% security_sid_to_context_force - 1.21% security_sid_to_context_core - 1.19% sidtab_entry_to_string - 1.20% sidtab_sid2str_get - 0.86% sidtab_sid2str_put.part.0 - 0.62% _raw_spin_lock_irqsave - 0.77% do_raw_spin_lock __pv_queued_spin_lock_slowpath - 0.84% selinux_determine_inode_label - 0.83% security_transition_sid 0.86% security_compute_sid.part.0 Which indicates the XFS overhead of creating the selinux xattr has been halved. This doesn't fix the CIL lock contention problem, just means it's not a limiting factor for this workload. Lock contention in the security subsystems is going to be an issue soon, though... Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> [djwong: fix compilation error when CONFIG_SECURITY=n] Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Gao Xiang <hsiangkao@redhat.com>
Diffstat (limited to 'fs/xfs/xfs_inode.h')
-rw-r--r--fs/xfs/xfs_inode.h6
1 files changed, 4 insertions, 2 deletions
diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index c2c26f8f4a81..13f4cd2e1f4f 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -379,7 +379,8 @@ int xfs_lookup(struct xfs_inode *dp, struct xfs_name *name,
struct xfs_inode **ipp, struct xfs_name *ci_name);
int xfs_create(struct user_namespace *mnt_userns,
struct xfs_inode *dp, struct xfs_name *name,
- umode_t mode, dev_t rdev, struct xfs_inode **ipp);
+ umode_t mode, dev_t rdev, bool need_xattr,
+ struct xfs_inode **ipp);
int xfs_create_tmpfile(struct user_namespace *mnt_userns,
struct xfs_inode *dp, umode_t mode,
struct xfs_inode **ipp);
@@ -421,7 +422,8 @@ xfs_extlen_t xfs_get_cowextsz_hint(struct xfs_inode *ip);
int xfs_dir_ialloc(struct user_namespace *mnt_userns,
struct xfs_trans **tpp, struct xfs_inode *dp,
umode_t mode, xfs_nlink_t nlink, dev_t dev,
- prid_t prid, struct xfs_inode **ipp);
+ prid_t prid, bool need_xattr,
+ struct xfs_inode **ipp);
static inline int
xfs_itruncate_extents(