From 1acf2e040721564d579297646862b8ea3dd4511b Mon Sep 17 00:00:00 2001 From: Davidlohr Bueso Date: Fri, 12 Dec 2014 16:54:39 -0800 Subject: [PATCH] mm/nommu: share the i_mmap_rwsem Shrinking/truncate logic can call nommu_shrink_inode_mappings() to verify that any shared mappings of the inode in question aren't broken (dead zone). afaict the only user being ramfs to handle the size change attribute. Pretty much a no-brainer to share the lock. Signed-off-by: Davidlohr Bueso Acked-by: "Kirill A. Shutemov" Acked-by: Hugh Dickins Cc: Oleg Nesterov Acked-by: Peter Zijlstra (Intel) Cc: Rik van Riel Cc: Srikar Dronamraju Acked-by: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/nommu.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/mm/nommu.c b/mm/nommu.c index 52a576553581..cd519e1cd8a7 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -2094,14 +2094,14 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size, high = (size + PAGE_SIZE - 1) >> PAGE_SHIFT; down_write(&nommu_region_sem); - i_mmap_lock_write(inode->i_mapping); + i_mmap_lock_read(inode->i_mapping); /* search for VMAs that fall within the dead zone */ vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, low, high) { /* found one - only interested if it's shared out of the page * cache */ if (vma->vm_flags & VM_SHARED) { - i_mmap_unlock_write(inode->i_mapping); + i_mmap_unlock_read(inode->i_mapping); up_write(&nommu_region_sem); return -ETXTBSY; /* not quite true, but near enough */ } @@ -2113,8 +2113,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size, * we don't check for any regions that start beyond the EOF as there * shouldn't be any */ - vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, - 0, ULONG_MAX) { + vma_interval_tree_foreach(vma, &inode->i_mapping->i_mmap, 0, ULONG_MAX) { if (!(vma->vm_flags & VM_SHARED)) continue; @@ -2129,7 +2128,7 @@ int nommu_shrink_inode_mappings(struct inode *inode, size_t size, } } - i_mmap_unlock_write(inode->i_mapping); + i_mmap_unlock_read(inode->i_mapping); up_write(&nommu_region_sem); return 0; } -- 2.20.1