fs/dcache: Track & report number of negative dentries

[mirror_ubuntu-eoan-kernel.git] / Documentation / sysctl / fs.txt

diff --git a/Documentation/sysctl/fs.txt b/Documentation/sysctl/fs.txt
index 819caf8ca05f8b4b16226c0f5d6f76068de09131..58649bd4fcfcc30de978b071143f6560b3d5a1e4 100644 (file)
--- a/Documentation/sysctl/fs.txt
+++ b/Documentation/sysctl/fs.txt
@@ -56,26 +56,32 @@ of any kernel data structures.
 
 dentry-state:
 
-From linux/fs/dentry.c:
+From linux/include/linux/dcache.h:
 --------------------------------------------------------------
-struct {
+struct dentry_stat_t dentry_stat {
         int nr_dentry;
         int nr_unused;
         int age_limit;         /* age in seconds */
         int want_pages;        /* pages requested by system */
-        int dummy[2];
-} dentry_stat = {0, 0, 45, 0,};
--------------------------------------------------------------- 
-
-Dentries are dynamically allocated and deallocated, and
-nr_dentry seems to be 0 all the time. Hence it's safe to
-assume that only nr_unused, age_limit and want_pages are
-used. Nr_unused seems to be exactly what its name says.
+        int nr_negative;       /* # of unused negative dentries */
+        int dummy;             /* Reserved for future use */
+};
+--------------------------------------------------------------
+
+Dentries are dynamically allocated and deallocated.
+
+nr_dentry shows the total number of dentries allocated (active
++ unused). nr_unused shows the number of dentries that are not
+actively used, but are saved in the LRU list for future reuse.
+
 Age_limit is the age in seconds after which dcache entries
 can be reclaimed when memory is short and want_pages is
 nonzero when shrink_dcache_pages() has been called and the
 dcache isn't pruned yet.
 
+nr_negative shows the number of unused dentries that are also
+negative dentries which do not mapped to actual files.
+
 ==============================================================
 
 dquot-max & dquot-nr: