3 files changed, 173 insertions, 138 deletions

diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 678fc72c3646..e6410d8edd0e 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -59,7 +59,6 @@ static void huge_pagevec_release(struct pagevec *pvec)
 static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 {
         struct inode *inode = file->f_dentry->d_inode;
-        struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
         loff_t len, vma_len;
         int ret;
 
@@ -87,9 +86,10 @@ static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
         if (!(vma->vm_flags & VM_WRITE) && len > inode->i_size)
                 goto out;
 
-        if (vma->vm_flags & VM_MAYSHARE)
-                if (hugetlb_extend_reservation(info, len >> HPAGE_SHIFT) != 0)
-                        goto out;
+        if (vma->vm_flags & VM_MAYSHARE &&
+            hugetlb_reserve_pages(inode, vma->vm_pgoff >> (HPAGE_SHIFT-PAGE_SHIFT),
+                                  len >> HPAGE_SHIFT))
+                goto out;
 
         ret = 0;
         hugetlb_prefault_arch_hook(vma->vm_mm);
@@ -195,12 +195,8 @@ static void truncate_hugepages(struct inode *inode, loff_t lstart)
         const pgoff_t start = lstart >> HPAGE_SHIFT;
         struct pagevec pvec;
         pgoff_t next;
-        int i;
+        int i, freed = 0;
 
-        hugetlb_truncate_reservation(HUGETLBFS_I(inode),
-                                     lstart >> HPAGE_SHIFT);
-        if (!mapping->nrpages)
-                return;
         pagevec_init(&pvec, 0);
         next = start;
         while (1) {
@@ -221,10 +217,12 @@ static void truncate_hugepages(struct inode *inode, loff_t lstart)
                         truncate_huge_page(page);
                         unlock_page(page);
                         hugetlb_put_quota(mapping);
+                        freed++;
                 }
                 huge_pagevec_release(&pvec);
         }
         BUG_ON(!lstart && mapping->nrpages);
+        hugetlb_unreserve_pages(inode, start, freed);
 }
 
 static void hugetlbfs_delete_inode(struct inode *inode)
@@ -366,6 +364,7 @@ static struct inode *hugetlbfs_get_inode(struct super_block *sb, uid_t uid,
                 inode->i_mapping->a_ops = &hugetlbfs_aops;
                 inode->i_mapping->backing_dev_info =&hugetlbfs_backing_dev_info;
                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+                INIT_LIST_HEAD(&inode->i_mapping->private_list);
                 info = HUGETLBFS_I(inode);
                 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, NULL);
                 switch (mode & S_IFMT) {
@@ -538,7 +537,6 @@ static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
                 hugetlbfs_inc_free_inodes(sbinfo);
                 return NULL;
         }
-        p->prereserved_hpages = 0;
         return &p->vfs_inode;
 }
 
@@ -781,8 +779,7 @@ struct file *hugetlb_zero_setup(size_t size)
                 goto out_file;
 
         error = -ENOMEM;
-        if (hugetlb_extend_reservation(HUGETLBFS_I(inode),
-                                       size >> HPAGE_SHIFT) != 0)
+        if (hugetlb_reserve_pages(inode, 0, size >> HPAGE_SHIFT))
                 goto out_inode;
 
         d_instantiate(dentry, inode);
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 4c5e610fe442..c25a38d8f600 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -23,6 +23,8 @@ int hugetlb_report_node_meminfo(int, char *);
 unsigned long hugetlb_total_pages(void);
 int hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
                         unsigned long address, int write_access);
+int hugetlb_reserve_pages(struct inode *inode, long from, long to);
+void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed);
 
 extern unsigned long max_huge_pages;
 extern const unsigned long hugetlb_zero, hugetlb_infinity;
@@ -139,8 +141,6 @@ struct hugetlbfs_sb_info {
 
 struct hugetlbfs_inode_info {
         struct shared_policy policy;
-        /* Protected by the (global) hugetlb_lock */
-        unsigned long prereserved_hpages;
         struct inode vfs_inode;
 };
 
@@ -157,10 +157,6 @@ static inline struct hugetlbfs_sb_info *HUGETLBFS_SB(struct super_block *sb)
 extern const struct file_operations hugetlbfs_file_operations;
 extern struct vm_operations_struct hugetlb_vm_ops;
 struct file *hugetlb_zero_setup(size_t);
-int hugetlb_extend_reservation(struct hugetlbfs_inode_info *info,
-                               unsigned long atleast_hpages);
-void hugetlb_truncate_reservation(struct hugetlbfs_inode_info *info,
-                                  unsigned long atmost_hpages);
 int hugetlb_get_quota(struct address_space *mapping);
 void hugetlb_put_quota(struct address_space *mapping);
 
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 832f676ca038..df499973255f 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -22,7 +22,7 @@
 #include "internal.h"
 
 const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
-static unsigned long nr_huge_pages, free_huge_pages, reserved_huge_pages;
+static unsigned long nr_huge_pages, free_huge_pages, resv_huge_pages;
 unsigned long max_huge_pages;
 static struct list_head hugepage_freelists[MAX_NUMNODES];
 static unsigned int nr_huge_pages_node[MAX_NUMNODES];
@@ -123,39 +123,13 @@ static int alloc_fresh_huge_page(void)
 static struct page *alloc_huge_page(struct vm_area_struct *vma,
                                     unsigned long addr)
 {
-        struct inode *inode = vma->vm_file->f_dentry->d_inode;
         struct page *page;
-        int use_reserve = 0;
-        unsigned long idx;
 
         spin_lock(&hugetlb_lock);
-
-        if (vma->vm_flags & VM_MAYSHARE) {
-
-                /* idx = radix tree index, i.e. offset into file in
-                 * HPAGE_SIZE units */
-                idx = ((addr - vma->vm_start) >> HPAGE_SHIFT)
-                        + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT));
-
-                /* The hugetlbfs specific inode info stores the number
-                 * of "guaranteed available" (huge) pages.  That is,
-                 * the first 'prereserved_hpages' pages of the inode
-                 * are either already instantiated, or have been
-                 * pre-reserved (by hugetlb_reserve_for_inode()). Here
-                 * we're in the process of instantiating the page, so
-                 * we use this to determine whether to draw from the
-                 * pre-reserved pool or the truly free pool. */
-                if (idx < HUGETLBFS_I(inode)->prereserved_hpages)
-                        use_reserve = 1;
-        }
-
-        if (!use_reserve) {
-                if (free_huge_pages <= reserved_huge_pages)
-                        goto fail;
-        } else {
-                BUG_ON(reserved_huge_pages == 0);
-                reserved_huge_pages--;
-        }
+        if (vma->vm_flags & VM_MAYSHARE)
+                resv_huge_pages--;
+        else if (free_huge_pages <= resv_huge_pages)
+                goto fail;
 
         page = dequeue_huge_page(vma, addr);
         if (!page)
@@ -165,96 +139,11 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
         set_page_refcounted(page);
         return page;
 
- fail:
-        WARN_ON(use_reserve); /* reserved allocations shouldn't fail */
+fail:
         spin_unlock(&hugetlb_lock);
         return NULL;
 }
 
-/* hugetlb_extend_reservation()
- *
- * Ensure that at least 'atleast' hugepages are, and will remain,
- * available to instantiate the first 'atleast' pages of the given
- * inode.  If the inode doesn't already have this many pages reserved
- * or instantiated, set aside some hugepages in the reserved pool to
- * satisfy later faults (or fail now if there aren't enough, rather
- * than getting the SIGBUS later).
- */
-int hugetlb_extend_reservation(struct hugetlbfs_inode_info *info,
-                               unsigned long atleast)
-{
-        struct inode *inode = &info->vfs_inode;
-        unsigned long change_in_reserve = 0;
-        int ret = 0;
-
-        spin_lock(&hugetlb_lock);
-        read_lock_irq(&inode->i_mapping->tree_lock);
-
-        if (info->prereserved_hpages >= atleast)
-                goto out;
-
-        /* Because we always call this on shared mappings, none of the
-         * pages beyond info->prereserved_hpages can have been
-         * instantiated, so we need to reserve all of them now. */
-        change_in_reserve = atleast - info->prereserved_hpages;
-
-        if ((reserved_huge_pages + change_in_reserve) > free_huge_pages) {
-                ret = -ENOMEM;
-                goto out;
-        }
-
-        reserved_huge_pages += change_in_reserve;
-        info->prereserved_hpages = atleast;
-
- out:
-        read_unlock_irq(&inode->i_mapping->tree_lock);
-        spin_unlock(&hugetlb_lock);
-
-        return ret;
-}
-
-/* hugetlb_truncate_reservation()
- *
- * This returns pages reserved for the given inode to the general free
- * hugepage pool.  If the inode has any pages prereserved, but not
- * instantiated, beyond offset (atmost << HPAGE_SIZE), then release
- * them.
- */
-void hugetlb_truncate_reservation(struct hugetlbfs_inode_info *info,
-                                  unsigned long atmost)
-{
-        struct inode *inode = &info->vfs_inode;
-        struct address_space *mapping = inode->i_mapping;
-        unsigned long idx;
-        unsigned long change_in_reserve = 0;
-        struct page *page;
-
-        spin_lock(&hugetlb_lock);
-        read_lock_irq(&inode->i_mapping->tree_lock);
-
-        if (info->prereserved_hpages <= atmost)
-                goto out;
-
-        /* Count pages which were reserved, but not instantiated, and
-         * which we can now release. */
-        for (idx = atmost; idx < info->prereserved_hpages; idx++) {
-                page = radix_tree_lookup(&mapping->page_tree, idx);
-                if (!page)
-                        /* Pages which are already instantiated can't
-                         * be unreserved (and in fact have already
-                         * been removed from the reserved pool) */
-                        change_in_reserve++;
-        }
-
-        BUG_ON(reserved_huge_pages < change_in_reserve);
-        reserved_huge_pages -= change_in_reserve;
-        info->prereserved_hpages = atmost;
-
- out:
-        read_unlock_irq(&inode->i_mapping->tree_lock);
-        spin_unlock(&hugetlb_lock);
-}
-
 static int __init hugetlb_init(void)
 {
         unsigned long i;
@@ -334,7 +223,7 @@ static unsigned long set_max_huge_pages(unsigned long count)
                 return nr_huge_pages;
 
         spin_lock(&hugetlb_lock);
-        count = max(count, reserved_huge_pages);
+        count = max(count, resv_huge_pages);
         try_to_free_low(count);
         while (count < nr_huge_pages) {
                 struct page *page = dequeue_huge_page(NULL, 0);
@@ -361,11 +250,11 @@ int hugetlb_report_meminfo(char *buf)
         return sprintf(buf,
                         "HugePages_Total: %5lu\n"
                         "HugePages_Free:  %5lu\n"
-                        "HugePages_Rsvd:  %5lu\n"
+                        "HugePages_Rsvd:  %5lu\n"
                         "Hugepagesize:    %5lu kB\n",
                         nr_huge_pages,
                         free_huge_pages,
-                        reserved_huge_pages,
+                        resv_huge_pages,
                         HPAGE_SIZE/1024);
 }
 
@@ -754,3 +643,156 @@ void hugetlb_change_protection(struct vm_area_struct *vma,
         flush_tlb_range(vma, start, end);
 }
 
+struct file_region {
+        struct list_head link;
+        long from;
+        long to;
+};
+
+static long region_add(struct list_head *head, long f, long t)
+{
+        struct file_region *rg, *nrg, *trg;
+
+        /* Locate the region we are either in or before. */
+        list_for_each_entry(rg, head, link)
+                if (f <= rg->to)
+                        break;
+
+        /* Round our left edge to the current segment if it encloses us. */
+        if (f > rg->from)
+                f = rg->from;
+
+        /* Check for and consume any regions we now overlap with. */
+        nrg = rg;
+        list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
+                if (&rg->link == head)
+                        break;
+                if (rg->from > t)
+                        break;
+
+                /* If this area reaches higher then extend our area to
+                 * include it completely.  If this is not the first area
+                 * which we intend to reuse, free it. */
+                if (rg->to > t)
+                        t = rg->to;
+                if (rg != nrg) {
+                        list_del(&rg->link);
+                        kfree(rg);
+                }
+        }
+        nrg->from = f;
+        nrg->to = t;
+        return 0;
+}
+
+static long region_chg(struct list_head *head, long f, long t)
+{
+        struct file_region *rg, *nrg;
+        long chg = 0;
+
+        /* Locate the region we are before or in. */
+        list_for_each_entry(rg, head, link)
+                if (f <= rg->to)
+                        break;
+
+        /* If we are below the current region then a new region is required.
+         * Subtle, allocate a new region at the position but make it zero
+         * size such that we can guarentee to record the reservation. */
+        if (&rg->link == head || t < rg->from) {
+                nrg = kmalloc(sizeof(*nrg), GFP_KERNEL);
+                if (nrg == 0)
+                        return -ENOMEM;
+                nrg->from = f;
+                nrg->to   = f;
+                INIT_LIST_HEAD(&nrg->link);
+                list_add(&nrg->link, rg->link.prev);
+
+                return t - f;
+        }
+
+        /* Round our left edge to the current segment if it encloses us. */
+        if (f > rg->from)
+                f = rg->from;
+        chg = t - f;
+
+        /* Check for and consume any regions we now overlap with. */
+        list_for_each_entry(rg, rg->link.prev, link) {
+                if (&rg->link == head)
+                        break;
+                if (rg->from > t)
+                        return chg;
+
+                /* We overlap with this area, if it extends futher than
+                 * us then we must extend ourselves.  Account for its
+                 * existing reservation. */
+                if (rg->to > t) {
+                        chg += rg->to - t;
+                        t = rg->to;
+                }
+                chg -= rg->to - rg->from;
+        }
+        return chg;
+}
+
+static long region_truncate(struct list_head *head, long end)
+{
+        struct file_region *rg, *trg;
+        long chg = 0;
+
+        /* Locate the region we are either in or before. */
+        list_for_each_entry(rg, head, link)
+                if (end <= rg->to)
+                        break;
+        if (&rg->link == head)
+                return 0;
+
+        /* If we are in the middle of a region then adjust it. */
+        if (end > rg->from) {
+                chg = rg->to - end;
+                rg->to = end;
+                rg = list_entry(rg->link.next, typeof(*rg), link);
+        }
+
+        /* Drop any remaining regions. */
+        list_for_each_entry_safe(rg, trg, rg->link.prev, link) {
+                if (&rg->link == head)
+                        break;
+                chg += rg->to - rg->from;
+                list_del(&rg->link);
+                kfree(rg);
+        }
+        return chg;
+}
+
+static int hugetlb_acct_memory(long delta)
+{
+        int ret = -ENOMEM;
+
+        spin_lock(&hugetlb_lock);
+        if ((delta + resv_huge_pages) <= free_huge_pages) {
+                resv_huge_pages += delta;
+                ret = 0;
+        }
+        spin_unlock(&hugetlb_lock);
+        return ret;
+}
+
+int hugetlb_reserve_pages(struct inode *inode, long from, long to)
+{
+        long ret, chg;
+
+        chg = region_chg(&inode->i_mapping->private_list, from, to);
+        if (chg < 0)
+                return chg;
+        ret = hugetlb_acct_memory(chg);
+        if (ret < 0)
+                return ret;
+        region_add(&inode->i_mapping->private_list, from, to);
+        return 0;
+}
+
+void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
+{
+        long chg = region_truncate(&inode->i_mapping->private_list, offset);
+        hugetlb_acct_memory(freed - chg);
+}