hugetlbfs: accept subpool min_size mount option and setup accordingly

Make 'min_size=<value>' be an option when mounting a hugetlbfs.  This
option takes the same value as the 'size' option.  min_size can be
specified without specifying size.  If both are specified, min_size must
be less that or equal to size else the mount will fail.  If min_size is
specified, then at mount time an attempt is made to reserve min_size
pages.  If the reservation fails, the mount fails.  At umount time, the
reserved pages are released.

Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 71 insertions, 19 deletions

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index db76cec3ce21..3a8f12762821 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -47,9 +47,10 @@ struct hugetlbfs_config {
         kuid_t   uid;
         kgid_t   gid;
         umode_t mode;
-        long    nr_blocks;
+        long    max_hpages;
         long    nr_inodes;
         struct hstate *hstate;
+        long    min_hpages;
 };
 
 struct hugetlbfs_inode_info {
@@ -67,7 +68,7 @@ int sysctl_hugetlb_shm_group;
 enum {
         Opt_size, Opt_nr_inodes,
         Opt_mode, Opt_uid, Opt_gid,
-        Opt_pagesize,
+        Opt_pagesize, Opt_min_size,
         Opt_err,
 };
 
@@ -78,6 +79,7 @@ static const match_table_t tokens = {
         {Opt_uid,       "uid=%u"},
         {Opt_gid,       "gid=%u"},
         {Opt_pagesize,  "pagesize=%s"},
+        {Opt_min_size,  "min_size=%s"},
         {Opt_err,       NULL},
 };
 
@@ -754,14 +756,38 @@ static const struct super_operations hugetlbfs_ops = {
         .show_options   = generic_show_options,
 };
 
+enum { NO_SIZE, SIZE_STD, SIZE_PERCENT };
+
+/*
+ * Convert size option passed from command line to number of huge pages
+ * in the pool specified by hstate.  Size option could be in bytes
+ * (val_type == SIZE_STD) or percentage of the pool (val_type == SIZE_PERCENT).
+ */
+static long long
+hugetlbfs_size_to_hpages(struct hstate *h, unsigned long long size_opt,
+                                                                int val_type)
+{
+        if (val_type == NO_SIZE)
+                return -1;
+
+        if (val_type == SIZE_PERCENT) {
+                size_opt <<= huge_page_shift(h);
+                size_opt *= h->max_huge_pages;
+                do_div(size_opt, 100);
+        }
+
+        size_opt >>= huge_page_shift(h);
+        return size_opt;
+}
+
 static int
 hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
 {
         char *p, *rest;
         substring_t args[MAX_OPT_ARGS];
         int option;
-        unsigned long long size = 0;
-        enum { NO_SIZE, SIZE_STD, SIZE_PERCENT } setsize = NO_SIZE;
+        unsigned long long max_size_opt = 0, min_size_opt = 0;
+        int max_val_type = NO_SIZE, min_val_type = NO_SIZE;
 
         if (!options)
                 return 0;
@@ -799,10 +825,10 @@ hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
                         /* memparse() will accept a K/M/G without a digit */
                         if (!isdigit(*args[0].from))
                                 goto bad_val;
-                        size = memparse(args[0].from, &rest);
-                        setsize = SIZE_STD;
+                        max_size_opt = memparse(args[0].from, &rest);
+                        max_val_type = SIZE_STD;
                         if (*rest == '%')
-                                setsize = SIZE_PERCENT;
+                                max_val_type = SIZE_PERCENT;
                         break;
                 }
 
@@ -825,6 +851,17 @@ hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
                         break;
                 }
 
+                case Opt_min_size: {
+                        /* memparse() will accept a K/M/G without a digit */
+                        if (!isdigit(*args[0].from))
+                                goto bad_val;
+                        min_size_opt = memparse(args[0].from, &rest);
+                        min_val_type = SIZE_STD;
+                        if (*rest == '%')
+                                min_val_type = SIZE_PERCENT;
+                        break;
+                }
+
                 default:
                         pr_err("Bad mount option: \"%s\"\n", p);
                         return -EINVAL;
@@ -832,15 +869,22 @@ hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
                 }
         }
 
-        /* Do size after hstate is set up */
-        if (setsize > NO_SIZE) {
-                struct hstate *h = pconfig->hstate;
-                if (setsize == SIZE_PERCENT) {
-                        size <<= huge_page_shift(h);
-                        size *= h->max_huge_pages;
-                        do_div(size, 100);
-                }
-                pconfig->nr_blocks = (size >> huge_page_shift(h));
+        /*
+         * Use huge page pool size (in hstate) to convert the size
+         * options to number of huge pages.  If NO_SIZE, -1 is returned.
+         */
+        pconfig->max_hpages = hugetlbfs_size_to_hpages(pconfig->hstate,
+                                                max_size_opt, max_val_type);
+        pconfig->min_hpages = hugetlbfs_size_to_hpages(pconfig->hstate,
+                                                min_size_opt, min_val_type);
+
+        /*
+         * If max_size was specified, then min_size must be smaller
+         */
+        if (max_val_type > NO_SIZE &&
+            pconfig->min_hpages > pconfig->max_hpages) {
+                pr_err("minimum size can not be greater than maximum size\n");
+                return -EINVAL;
         }
 
         return 0;
@@ -859,12 +903,13 @@ hugetlbfs_fill_super(struct super_block *sb, void *data, int silent)
 
         save_mount_options(sb, data);
 
-        config.nr_blocks = -1; /* No limit on size by default */
+        config.max_hpages = -1; /* No limit on size by default */
         config.nr_inodes = -1; /* No limit on number of inodes by default */
         config.uid = current_fsuid();
         config.gid = current_fsgid();
         config.mode = 0755;
         config.hstate = &default_hstate;
+        config.min_hpages = -1; /* No default minimum size */
         ret = hugetlbfs_parse_options(data, &config);
         if (ret)
                 return ret;
@@ -878,8 +923,15 @@ hugetlbfs_fill_super(struct super_block *sb, void *data, int silent)
         sbinfo->max_inodes = config.nr_inodes;
         sbinfo->free_inodes = config.nr_inodes;
         sbinfo->spool = NULL;
-        if (config.nr_blocks != -1) {
-                sbinfo->spool = hugepage_new_subpool(config.nr_blocks);
+        /*
+         * Allocate and initialize subpool if maximum or minimum size is
+         * specified.  Any needed reservations (for minimim size) are taken
+         * taken when the subpool is created.
+         */
+        if (config.max_hpages != -1 || config.min_hpages != -1) {
+                sbinfo->spool = hugepage_new_subpool(config.hstate,
+                                                        config.max_hpages,
+                                                        config.min_hpages);
                 if (!sbinfo->spool)
                         goto out_free;
         }