From: Badari Pulavarty Date: Fri, 6 Jan 2006 08:10:38 +0000 (-0800) Subject: [PATCH] madvise(MADV_REMOVE): remove pages from tmpfs shm backing store X-Git-Tag: v2.6.16-rc1~936^2~277 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f6b3ec238d12c8cc6cc71490c6e3127988460349;p=linux-2.6 [PATCH] madvise(MADV_REMOVE): remove pages from tmpfs shm backing store Here is the patch to implement madvise(MADV_REMOVE) - which frees up a given range of pages & its associated backing store. Current implementation supports only shmfs/tmpfs and other filesystems return -ENOSYS. "Some app allocates large tmpfs files, then when some task quits and some client disconnect, some memory can be released. However the only way to release tmpfs-swap is to MADV_REMOVE". - Andrea Arcangeli Databases want to use this feature to drop a section of their bufferpool (shared memory segments) - without writing back to disk/swap space. This feature is also useful for supporting hot-plug memory on UML. Concerns raised by Andrew Morton: - "We have no plan for holepunching! If we _do_ have such a plan (or might in the future) then what would the API look like? I think sys_holepunch(fd, start, len), so we should start out with that." - Using madvise is very weird, because people will ask "why do I need to mmap my file before I can stick a hole in it?" - None of the other madvise operations call into the filesystem in this manner. A broad question is: is this capability an MM operation or a filesytem operation? truncate, for example, is a filesystem operation which sometimes has MM side-effects. madvise is an mm operation and with this patch, it gains FS side-effects, only they're really, really significant ones." Comments: - Andrea suggested the fs operation too but then it's more efficient to have it as a mm operation with fs side effects, because they don't immediatly know fd and physical offset of the range. It's possible to fixup in userland and to use the fs operation but it's more expensive, the vmas are already in the kernel and we can use them. Short term plan & Future Direction: - We seem to need this interface only for shmfs/tmpfs files in the short term. We have to add hooks into the filesystem for correctness and completeness. This is what this patch does. - In the future, plan is to support both fs and mmap apis also. This also involves (other) filesystem specific functions to be implemented. - Current patch doesn't support VM_NONLINEAR - which can be addressed in the future. Signed-off-by: Badari Pulavarty Cc: Hugh Dickins Cc: Andrea Arcangeli Cc: Michael Kerrisk Cc: Ulrich Drepper Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/asm-alpha/mman.h b/include/asm-alpha/mman.h index eb9c279045..f6439532a2 100644 --- a/include/asm-alpha/mman.h +++ b/include/asm-alpha/mman.h @@ -42,6 +42,7 @@ #define MADV_WILLNEED 3 /* will need these pages */ #define MADV_SPACEAVAIL 5 /* ensure resources are available */ #define MADV_DONTNEED 6 /* don't need these pages */ +#define MADV_REMOVE 7 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-arm/mman.h b/include/asm-arm/mman.h index 8e4f69c4fa..f0bebca2ac 100644 --- a/include/asm-arm/mman.h +++ b/include/asm-arm/mman.h @@ -35,6 +35,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-arm26/mman.h b/include/asm-arm26/mman.h index cc27b82402..0ed7780541 100644 --- a/include/asm-arm26/mman.h +++ b/include/asm-arm26/mman.h @@ -35,6 +35,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-cris/mman.h b/include/asm-cris/mman.h index 8570e72b95..5a382b8bf3 100644 --- a/include/asm-cris/mman.h +++ b/include/asm-cris/mman.h @@ -37,6 +37,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-frv/mman.h b/include/asm-frv/mman.h index c684720dfb..8af4a41c25 100644 --- a/include/asm-frv/mman.h +++ b/include/asm-frv/mman.h @@ -35,6 +35,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-h8300/mman.h b/include/asm-h8300/mman.h index 63f727a598..744a8fb485 100644 --- a/include/asm-h8300/mman.h +++ b/include/asm-h8300/mman.h @@ -35,6 +35,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-i386/mman.h b/include/asm-i386/mman.h index 196619a838..ba4941e6f6 100644 --- a/include/asm-i386/mman.h +++ b/include/asm-i386/mman.h @@ -35,6 +35,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-ia64/mman.h b/include/asm-ia64/mman.h index 1c0a73af14..828beb24a2 100644 --- a/include/asm-ia64/mman.h +++ b/include/asm-ia64/mman.h @@ -43,6 +43,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-m32r/mman.h b/include/asm-m32r/mman.h index 011f6d9ec5..12e29747bc 100644 --- a/include/asm-m32r/mman.h +++ b/include/asm-m32r/mman.h @@ -37,6 +37,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-m68k/mman.h b/include/asm-m68k/mman.h index f831c4eeae..ea262ab88b 100644 --- a/include/asm-m68k/mman.h +++ b/include/asm-m68k/mman.h @@ -35,6 +35,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-mips/mman.h b/include/asm-mips/mman.h index 62060957ba..dd17c8bd62 100644 --- a/include/asm-mips/mman.h +++ b/include/asm-mips/mman.h @@ -65,6 +65,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-parisc/mman.h b/include/asm-parisc/mman.h index e829607eb8..736b0abcac 100644 --- a/include/asm-parisc/mman.h +++ b/include/asm-parisc/mman.h @@ -38,6 +38,7 @@ #define MADV_SPACEAVAIL 5 /* insure that resources are reserved */ #define MADV_VPS_PURGE 6 /* Purge pages from VM page cache */ #define MADV_VPS_INHERIT 7 /* Inherit parents page size */ +#define MADV_REMOVE 8 /* remove these pages & resources */ /* The range 12-64 is reserved for page size specification. */ #define MADV_4K_PAGES 12 /* Use 4K pages */ diff --git a/include/asm-powerpc/mman.h b/include/asm-powerpc/mman.h index f5e5342fca..a2e34c21b4 100644 --- a/include/asm-powerpc/mman.h +++ b/include/asm-powerpc/mman.h @@ -44,6 +44,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-s390/mman.h b/include/asm-s390/mman.h index ea86bd1220..c8d5409b5d 100644 --- a/include/asm-s390/mman.h +++ b/include/asm-s390/mman.h @@ -43,6 +43,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-sh/mman.h b/include/asm-sh/mman.h index 3ebab5f79d..693bd55a37 100644 --- a/include/asm-sh/mman.h +++ b/include/asm-sh/mman.h @@ -35,6 +35,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-sparc/mman.h b/include/asm-sparc/mman.h index 138eb81dd7..98435ad861 100644 --- a/include/asm-sparc/mman.h +++ b/include/asm-sparc/mman.h @@ -54,6 +54,7 @@ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ #define MADV_FREE 0x5 /* (Solaris) contents can be freed */ +#define MADV_REMOVE 0x6 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-sparc64/mman.h b/include/asm-sparc64/mman.h index 01cecf5435..cb4b615619 100644 --- a/include/asm-sparc64/mman.h +++ b/include/asm-sparc64/mman.h @@ -54,6 +54,7 @@ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ #define MADV_FREE 0x5 /* (Solaris) contents can be freed */ +#define MADV_REMOVE 0x6 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-v850/mman.h b/include/asm-v850/mman.h index e2b90081b5..edc7996519 100644 --- a/include/asm-v850/mman.h +++ b/include/asm-v850/mman.h @@ -32,6 +32,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-x86_64/mman.h b/include/asm-x86_64/mman.h index 78e60a4fd4..d0e97b74f7 100644 --- a/include/asm-x86_64/mman.h +++ b/include/asm-x86_64/mman.h @@ -36,6 +36,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/asm-xtensa/mman.h b/include/asm-xtensa/mman.h index 9a95a45df9..082a750492 100644 --- a/include/asm-xtensa/mman.h +++ b/include/asm-xtensa/mman.h @@ -72,6 +72,7 @@ #define MADV_SEQUENTIAL 0x2 /* read-ahead aggressively */ #define MADV_WILLNEED 0x3 /* pre-fault pages */ #define MADV_DONTNEED 0x4 /* discard these pages */ +#define MADV_REMOVE 0x5 /* remove these pages & resources */ /* compatibility flags */ #define MAP_ANON MAP_ANONYMOUS diff --git a/include/linux/fs.h b/include/linux/fs.h index ed9a41a71e..115e72be25 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -1050,6 +1050,7 @@ struct inode_operations { ssize_t (*getxattr) (struct dentry *, const char *, void *, size_t); ssize_t (*listxattr) (struct dentry *, char *, size_t); int (*removexattr) (struct dentry *, const char *); + void (*truncate_range)(struct inode *, loff_t, loff_t); }; struct seq_file; diff --git a/include/linux/mm.h b/include/linux/mm.h index 92acae9f1f..6c9be99429 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -690,6 +690,7 @@ static inline void unmap_shared_mapping_range(struct address_space *mapping, } extern int vmtruncate(struct inode * inode, loff_t offset); +extern int vmtruncate_range(struct inode * inode, loff_t offset, loff_t end); extern int install_page(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, struct page *page, pgprot_t prot); extern int install_file_pte(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, unsigned long pgoff, pgprot_t prot); extern int __handle_mm_fault(struct mm_struct *mm,struct vm_area_struct *vma, unsigned long address, int write_access); diff --git a/mm/madvise.c b/mm/madvise.c index 2b7cf0400a..ae0ae3ea29 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -140,6 +140,36 @@ static long madvise_dontneed(struct vm_area_struct * vma, return 0; } +/* + * Application wants to free up the pages and associated backing store. + * This is effectively punching a hole into the middle of a file. + * + * NOTE: Currently, only shmfs/tmpfs is supported for this operation. + * Other filesystems return -ENOSYS. + */ +static long madvise_remove(struct vm_area_struct *vma, + unsigned long start, unsigned long end) +{ + struct address_space *mapping; + loff_t offset, endoff; + + if (vma->vm_flags & (VM_LOCKED|VM_NONLINEAR|VM_HUGETLB)) + return -EINVAL; + + if (!vma->vm_file || !vma->vm_file->f_mapping + || !vma->vm_file->f_mapping->host) { + return -EINVAL; + } + + mapping = vma->vm_file->f_mapping; + + offset = (loff_t)(start - vma->vm_start) + + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); + endoff = (loff_t)(end - vma->vm_start - 1) + + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); + return vmtruncate_range(mapping->host, offset, endoff); +} + static long madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, unsigned long start, unsigned long end, int behavior) @@ -152,6 +182,9 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, case MADV_RANDOM: error = madvise_behavior(vma, prev, start, end, behavior); break; + case MADV_REMOVE: + error = madvise_remove(vma, start, end); + break; case MADV_WILLNEED: error = madvise_willneed(vma, prev, start, end); @@ -190,6 +223,8 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, * some pages ahead. * MADV_DONTNEED - the application is finished with the given range, * so the kernel can free resources associated with it. + * MADV_REMOVE - the application wants to free up the given range of + * pages and associated backing store. * * return values: * zero - success diff --git a/mm/memory.c b/mm/memory.c index d8dde07a36..e249088908 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1770,9 +1770,32 @@ out_big: out_busy: return -ETXTBSY; } - EXPORT_SYMBOL(vmtruncate); +int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end) +{ + struct address_space *mapping = inode->i_mapping; + + /* + * If the underlying filesystem is not going to provide + * a way to truncate a range of blocks (punch a hole) - + * we should return failure right now. + */ + if (!inode->i_op || !inode->i_op->truncate_range) + return -ENOSYS; + + down(&inode->i_sem); + down_write(&inode->i_alloc_sem); + unmap_mapping_range(mapping, offset, (end - offset), 1); + truncate_inode_pages_range(mapping, offset, end); + inode->i_op->truncate_range(inode, offset, end); + up_write(&inode->i_alloc_sem); + up(&inode->i_sem); + + return 0; +} +EXPORT_SYMBOL(vmtruncate_range); + /* * Primitive swap readahead code. We simply read an aligned block of * (1 << page_cluster) entries in the swap area. This method is chosen diff --git a/mm/shmem.c b/mm/shmem.c index d9fc277940..65c148efa2 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -457,7 +457,7 @@ static void shmem_free_pages(struct list_head *next) } while (next); } -static void shmem_truncate(struct inode *inode) +static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end) { struct shmem_inode_info *info = SHMEM_I(inode); unsigned long idx; @@ -475,18 +475,27 @@ static void shmem_truncate(struct inode *inode) long nr_swaps_freed = 0; int offset; int freed; + int punch_hole = 0; inode->i_ctime = inode->i_mtime = CURRENT_TIME; - idx = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; + idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; if (idx >= info->next_index) return; spin_lock(&info->lock); info->flags |= SHMEM_TRUNCATE; - limit = info->next_index; - info->next_index = idx; + if (likely(end == (loff_t) -1)) { + limit = info->next_index; + info->next_index = idx; + } else { + limit = (end + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; + if (limit > info->next_index) + limit = info->next_index; + punch_hole = 1; + } + topdir = info->i_indirect; - if (topdir && idx <= SHMEM_NR_DIRECT) { + if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { info->i_indirect = NULL; nr_pages_to_free++; list_add(&topdir->lru, &pages_to_free); @@ -573,11 +582,12 @@ static void shmem_truncate(struct inode *inode) set_page_private(subdir, page_private(subdir) - freed); if (offset) spin_unlock(&info->lock); - BUG_ON(page_private(subdir) > offset); + if (!punch_hole) + BUG_ON(page_private(subdir) > offset); } if (offset) offset = 0; - else if (subdir) { + else if (subdir && !page_private(subdir)) { dir[diroff] = NULL; nr_pages_to_free++; list_add(&subdir->lru, &pages_to_free); @@ -594,7 +604,7 @@ done2: * Also, though shmem_getpage checks i_size before adding to * cache, no recheck after: so fix the narrow window there too. */ - truncate_inode_pages(inode->i_mapping, inode->i_size); + truncate_inode_pages_range(inode->i_mapping, start, end); } spin_lock(&info->lock); @@ -614,6 +624,11 @@ done2: } } +static void shmem_truncate(struct inode *inode) +{ + shmem_truncate_range(inode, inode->i_size, (loff_t)-1); +} + static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) { struct inode *inode = dentry->d_inode; @@ -2083,6 +2098,7 @@ static struct file_operations shmem_file_operations = { static struct inode_operations shmem_inode_operations = { .truncate = shmem_truncate, .setattr = shmem_notify_change, + .truncate_range = shmem_truncate_range, }; static struct inode_operations shmem_dir_inode_operations = {