The sysctl_vfs_cache_pressure belongs to fs/dcache.c, move it to
its own file from kernel/sysctl.c. As a part of fs/dcache.c cleaning,
sysctl_vfs_cache_pressure is changed to a static variable, and export
vfs_pressure_ratio with EXPORT_SYMBOL_GPL to be used by other files.
And move the unneeded include(linux/dcache.h).

Signed-off-by: Kaixiong Yu <redacted>
---
 fs/dcache.c            | 21 +++++++++++++++++++--
 include/linux/dcache.h |  7 +------
 kernel/sysctl.c        |  9 ---------
 3 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index 1af75fa68638..8717d5026cda 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c

@@ -73,8 +73,13 @@
  * If no ancestor relationship:
  * arbitrary, since it's serialized on rename_lock
  */
-int sysctl_vfs_cache_pressure __read_mostly = 100;
-EXPORT_SYMBOL_GPL(sysctl_vfs_cache_pressure);
+static int sysctl_vfs_cache_pressure __read_mostly = 100;
+
+unsigned long vfs_pressure_ratio(unsigned long val)
+{
+	return mult_frac(val, sysctl_vfs_cache_pressure, 100);
+}
+EXPORT_SYMBOL_GPL(vfs_pressure_ratio);