From: Waiman Long <longman@redhat.com>
To: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Jan Kara <jack@suse.cz>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Miklos Szeredi <mszeredi@redhat.com>,
Matthew Wilcox <willy@infradead.org>,
Larry Woodman <lwoodman@redhat.com>,
James Bottomley <James.Bottomley@HansenPartnership.com>,
"Wangkai (Kevin C)" <wangkai86@huawei.com>,
Waiman Long <longman@redhat.com>
Subject: [PATCH v5 6/6] fs/dcache: Make negative dentry limit enforcement sysctl parameter
Date: Mon, 2 Jul 2018 13:52:03 +0800 [thread overview]
Message-ID: <1530510723-24814-7-git-send-email-longman@redhat.com> (raw)
In-Reply-To: <1530510723-24814-1-git-send-email-longman@redhat.com>
It can be useful to make negative dentry limit enformcement a runtime
tuning parameter instead of just a boot time option. This allows system
administrator to disable limit enforcement in normal use, but turn it
on under certain circumstances.
A new /proc/sys/fs/enforce-neg-dentry-limit sysctl parameter is now
added. This is a boolean flag that accept a value of either 0 or 1
for disabling and enabling enforcement of negative dentry limit
respectively.
Signed-off-by: Waiman Long <longman@redhat.com>
---
Documentation/sysctl/fs.txt | 11 +++++++++++
fs/dcache.c | 4 +++-
include/linux/dcache.h | 4 ++++
kernel/sysctl.c | 11 +++++++++++
4 files changed, 29 insertions(+), 1 deletion(-)
diff --git a/Documentation/sysctl/fs.txt b/Documentation/sysctl/fs.txt
index a8e3f1f..ef8fd32 100644
--- a/Documentation/sysctl/fs.txt
+++ b/Documentation/sysctl/fs.txt
@@ -24,6 +24,7 @@ Currently, these files are in /proc/sys/fs:
- dentry-state
- dquot-max
- dquot-nr
+- enforce-neg-dentry-limit
- file-max
- file-nr
- inode-max
@@ -97,6 +98,16 @@ you might want to raise the limit.
==============================================================
+enforce-neg-dentry-limit:
+
+The file enforce-neg-dentry-limit, if present, contains a boolean
+flag (0 or 1) indicating if the negative dentries limit set by
+the "neg_dentry_pc" kernel parameter should be enforced or not.
+If enforced, excess negative dentries over the limit will be killed
+immediately after use.
+
+==============================================================
+
file-max & file-nr:
The value in file-max denotes the maximum number of file-
diff --git a/fs/dcache.c b/fs/dcache.c
index 77910c9..f50886e 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -146,7 +146,9 @@ struct dentry_stat_t dentry_stat = {
unlikely(!(sb)->s_root || !((sb)->s_flags & MS_ACTIVE))
#ifdef CONFIG_DCACHE_TRACK_NEG_ENTRY
-static int enforce_neg_dentry_limit __read_mostly;
+int enforce_neg_dentry_limit __read_mostly;
+EXPORT_SYMBOL_GPL(enforce_neg_dentry_limit);
+
static int neg_dentry_pc __read_mostly = NEG_DENTRY_PC_DEFAULT;
static long neg_dentry_percpu_limit __read_mostly;
static long neg_dentry_nfree_init __read_mostly; /* Free pool initial value */
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index 69b8cb3..bd7238a0 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -610,4 +610,8 @@ struct name_snapshot {
void take_dentry_name_snapshot(struct name_snapshot *, struct dentry *);
void release_dentry_name_snapshot(struct name_snapshot *);
+#ifdef CONFIG_DCACHE_TRACK_NEG_ENTRY
+extern int enforce_neg_dentry_limit;
+#endif
+
#endif /* __LINUX_DCACHE_H */
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 2d9837c..94f6f6c 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -1849,6 +1849,17 @@ static int sysrq_sysctl_handler(struct ctl_table *table, int write,
.proc_handler = proc_dointvec_minmax,
.extra1 = &one,
},
+#ifdef CONFIG_DCACHE_TRACK_NEG_ENTRY
+ {
+ .procname = "enforce-neg-dentry-limit",
+ .data = &enforce_neg_dentry_limit,
+ .maxlen = sizeof(enforce_neg_dentry_limit),
+ .mode = 0644,
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &zero,
+ .extra2 = &one,
+ },
+#endif
{ }
};
--
1.8.3.1
next prev parent reply other threads:[~2018-07-02 5:53 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-02 5:51 [PATCH v5 0/6] fs/dcache: Track & limit # of negative dentries Waiman Long
2018-07-02 5:51 ` [PATCH v5 1/6] fs/dcache: Track & report number " Waiman Long
2018-07-02 5:51 ` [PATCH v5 2/6] fs/dcache: Make negative dentry tracking configurable Waiman Long
2018-07-02 21:12 ` Andrew Morton
2018-07-03 0:59 ` Waiman Long
2018-07-02 5:52 ` [PATCH v5 3/6] fs/dcache: Enable automatic pruning of negative dentries Waiman Long
2018-07-02 5:52 ` [PATCH v5 4/6] fs/dcache: Spread negative dentry pruning across multiple CPUs Waiman Long
2018-07-02 5:52 ` [PATCH v5 5/6] fs/dcache: Allow optional enforcement of negative dentry limit Waiman Long
2018-07-02 5:52 ` Waiman Long [this message]
2018-07-02 19:34 ` [PATCH v5 0/6] fs/dcache: Track & limit # of negative dentries Linus Torvalds
2018-07-02 21:18 ` Andrew Morton
2018-07-02 22:21 ` Matthew Wilcox
2018-07-02 22:31 ` Linus Torvalds
2018-07-02 22:34 ` James Bottomley
2018-07-02 22:54 ` Linus Torvalds
2018-07-02 23:03 ` Linus Torvalds
2018-07-02 23:19 ` Andrew Morton
2018-07-02 23:28 ` Linus Torvalds
2018-07-03 1:38 ` Waiman Long
2018-07-03 9:18 ` Jan Kara
2018-07-14 17:35 ` Pavel Machek
2018-07-14 18:00 ` Linus Torvalds
2018-07-14 18:34 ` Al Viro
2018-07-14 18:36 ` Al Viro
2018-07-14 18:43 ` Linus Torvalds
2018-07-18 16:01 ` Waiman Long
2018-07-03 1:11 ` Waiman Long
2018-07-03 13:48 ` Vlastimil Babka
2018-07-03 0:46 ` Waiman Long
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