/* * Resizable virtual memory filesystem for Linux. * * Copyright (C) 2000 Linus Torvalds. * 2000 Transmeta Corp. * 2000-2001 Christoph Rohland * 2000-2001 SAP AG * 2002 Red Hat Inc. * Copyright (C) 2002-2005 Hugh Dickins. * Copyright (C) 2002-2005 VERITAS Software Corporation. * Copyright (C) 2004 Andi Kleen, SuSE Labs * * Extended attribute support for tmpfs: * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> * * This file is released under the GPL. */ /* * This virtual memory filesystem is heavily based on the ramfs. It * extends ramfs by the ability to use swap and honor resource limits * which makes it a completely usable filesystem. */ #include <linux/module.h> #include <linux/init.h> #include <linux/fs.h> #include <linux/xattr.h> #include <linux/generic_acl.h> #include <linux/mm.h> #include <linux/mman.h> #include <linux/file.h> #include <linux/swap.h> #include <linux/pagemap.h> #include <linux/string.h> #include <linux/slab.h> #include <linux/backing-dev.h> #include <linux/shmem_fs.h> #include <linux/mount.h> #include <linux/writeback.h> #include <linux/vfs.h> #include <linux/blkdev.h> #include <linux/security.h> #include <linux/swapops.h> #include <linux/mempolicy.h> #include <linux/namei.h> #include <linux/ctype.h> #include <linux/migrate.h> #include <linux/highmem.h> #include <linux/backing-dev.h> #include <asm/uaccess.h> #include <asm/div64.h> #include <asm/pgtable.h> /* This magic number is used in glibc for posix shared memory */ #define TMPFS_MAGIC 0x01021994 #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) #define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) #define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) #define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT) #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) /* info->flags needs VM_flags to handle pagein/truncate races efficiently */ #define SHMEM_PAGEIN VM_READ #define SHMEM_TRUNCATE VM_WRITE /* Definition to limit shmem_truncate's steps between cond_rescheds */ #define LATENCY_LIMIT 64 /* Pretend that each entry is of this size in directory's i_size */ #define BOGO_DIRENT_SIZE 20 /* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ enum sgp_type { SGP_QUICK, /* don't try more than file page cache lookup */ SGP_READ, /* don't exceed i_size, don't allocate page */ SGP_CACHE, /* don't exceed i_size, may allocate page */ SGP_WRITE, /* may exceed i_size, may allocate page */ }; static int shmem_getpage(struct inode *inode, unsigned long idx, struct page **pagep, enum sgp_type sgp, int *type); static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) { /* * The above definition of ENTRIES_PER_PAGE, and the use of * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: * might be reconsidered if it ever diverges from PAGE_SIZE. */ return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT); } static inline void shmem_dir_free(struct page *page) { __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); } static struct page **shmem_dir_map(struct page *page) { return (struct page **)kmap_atomic(page, KM_USER0); } static inline void shmem_dir_unmap(struct page **dir) { kunmap_atomic(dir, KM_USER0); } static swp_entry_t *shmem_swp_map(struct page *page) { return (swp_entry_t *)kmap_atomic(page, KM_USER1); } static inline void shmem_swp_balance_unmap(void) { /* * When passing a pointer to an i_direct entry, to code which * also handles indirect entries and so will shmem_swp_unmap, * we must arrange for the preempt count to remain in balance. * What kmap_atomic of a lowmem page does depends on config * and architecture, so pretend to kmap_atomic some lowmem page. */ (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); } static inline void shmem_swp_unmap(swp_entry_t *entry) { kunmap_atomic(entry, KM_USER1); } static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) { return sb->s_fs_info; } /* * shmem_file_setup pre-accounts the whole fixed size of a VM object, * for shared memory and for shared anonymous (/dev/zero) mappings * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), * consistent with the pre-accounting of private mappings ... */ static inline int shmem_acct_size(unsigned long flags, loff_t size) { return (flags & VM_ACCOUNT)? security_vm_enough_memory(VM_ACCT(size)): 0; } static inline void shmem_unacct_size(unsigned long flags, loff_t size) { if (flags & VM_ACCOUNT) vm_unacct_memory(VM_ACCT(size)); } /* * ... whereas tmpfs objects are accounted incrementally as * pages are allocated, in order to allow huge sparse files. * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. */ static inline int shmem_acct_block(unsigned long flags) { return (flags & VM_ACCOUNT)? 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE)); } static inline void shmem_unacct_blocks(unsigned long flags, long pages) { if (!(flags & VM_ACCOUNT)) vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); } static struct super_operations shmem_ops; static const struct address_space_operations shmem_aops; static const struct file_operations shmem_file_operations; static const struct inode_operations shmem_inode_operations; static const struct inode_operations shmem_dir_inode_operations; static const struct inode_operations shmem_special_inode_operations; static struct vm_operations_struct shmem_vm_ops; static struct backing_dev_info shmem_backing_dev_info __read_mostly = { .ra_pages = 0, /* No readahead */ .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, .unplug_io_fn = default_unplug_io_fn, }; static LIST_HEAD(shmem_swaplist); static DEFINE_SPINLOCK(shmem_swaplist_lock); static void shmem_free_blocks(struct inode *inode, long pages) { struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); if (sbinfo->max_blocks) { spin_lock(&sbinfo->stat_lock); sbinfo->free_blocks += pages; inode->i_blocks -= pages*BLOCKS_PER_PAGE; spin_unlock(&sbinfo->stat_lock); } } /* * shmem_recalc_inode - recalculate the size of an inode * * @inode: inode to recalc * * We have to calculate the free blocks since the mm can drop * undirtied hole pages behind our back. * * But normally info->alloced == inode->i_mapping->nrpages + info->swapped * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) * * It has to be called with the spinlock held. */ static void shmem_recalc_inode(struct inode *inode) { struct shmem_inode_info *info = SHMEM_I(inode); long freed; freed = info->alloced - info->swapped - inode->i_mapping->nrpages; if (freed > 0) { info->alloced -= freed; shmem_unacct_blocks(info->flags, freed); shmem_free_blocks(inode, freed); } } /* * shmem_swp_entry - find the swap vector position in the info structure * * @info: info structure for the inode * @index: index of the page to find * @page: optional page to add to the structure. Has to be preset to * all zeros * * If there is no space allocated yet it will return NULL when * page is NULL, else it will use the page for the needed block, * setting it to NULL on return to indicate that it has been used. * * The swap vector is organized the following way: * * There are SHMEM_NR_DIRECT entries directly stored in the * shmem_inode_info structure. So small files do not need an addional * allocation. * * For pages with index > SHMEM_NR_DIRECT there is the pointer * i_indirect which points to a page which holds in the first half * doubly indirect blocks, in the second half triple indirect blocks: * * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the * following layout (for SHMEM_NR_DIRECT == 16): * * i_indirect -> dir --> 16-19 * | +-> 20-23 * | * +-->dir2 --> 24-27 * | +-> 28-31 * | +-> 32-35 * | +-> 36-39 * | * +-->dir3 --> 40-43 * +-> 44-47 * +-> 48-51 * +-> 52-55 */ static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) { unsigned long offset; struct page **dir; struct page *subdir; if (index < SHMEM_NR_DIRECT) { shmem_swp_balance_unmap(); return info->i_direct+index; } if (!info->i_indirect) { if (page) { info->i_indirect = *page; *page = NULL; } return NULL; /* need another page */ } index -= SHMEM_NR_DIRECT; offset = index % ENTRIES_PER_PAGE; index /= ENTRIES_PER_PAGE; dir = shmem_dir_map(info->i_indirect); if (index >= ENTRIES_PER_PAGE/2) { index -= ENTRIES_PER_PAGE/2; dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; index %= ENTRIES_PER_PAGE; subdir = *dir; if (!subdir) { if (page) { *dir = *page; *page = NULL; } shmem_dir_unmap(dir); return NULL; /* need another page */ } shmem_dir_unmap(dir); dir = shmem_dir_map(subdir); } dir += index; subdir = *dir; if (!subdir) { if (!page || !(subdir = *page)) { shmem_dir_unmap(dir); return NULL; /* need a page */ } *dir = subdir; *page = NULL; } shmem_dir_unmap(dir); return shmem_swp_map(subdir) + offset; } static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) { long incdec = value? 1: -1; entry->val = value; info->swapped += incdec; if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { struct page *page = kmap_atomic_to_page(entry); set_page_private(page, page_private(page) + incdec); } } /* * shmem_swp_alloc - get the position of the swap entry for the page. * If it does not exist allocate the entry. * * @info: info structure for the inode * @index: index of the page to find * @sgp: check and recheck i_size? skip allocation? */ static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) { struct inode *inode = &info->vfs_inode; struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); struct page *page = NULL; swp_entry_t *entry; if (sgp != SGP_WRITE && ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) return ERR_PTR(-EINVAL); while (!(entry = shmem_swp_entry(info, index, &page))) { if (sgp == SGP_READ) return shmem_swp_map(ZERO_PAGE(0)); /* * Test free_blocks against 1 not 0, since we have 1 data * page (and perhaps indirect index pages) yet to allocate: * a waste to allocate index if we cannot allocate data. */ if (sbinfo->max_blocks) { spin_lock(&sbinfo->stat_lock); if (sbinfo->free_blocks <= 1) { spin_unlock(&sbinfo->stat_lock); return ERR_PTR(-ENOSPC); } sbinfo->free_blocks--; inode->i_blocks += BLOCKS_PER_PAGE; spin_unlock(&sbinfo->stat_lock); } spin_unlock(&info->lock); page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO); if (page) set_page_private(page, 0); spin_lock(&info->lock); if (!page) { shmem_free_blocks(inode, 1); return ERR_PTR(-ENOMEM); } if (sgp != SGP_WRITE && ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { entry = ERR_PTR(-EINVAL); break; } if (info->next_index <= index) info->next_index = index + 1; } if (page) { /* another task gave its page, or truncated the file */ shmem_free_blocks(inode, 1); shmem_dir_free(page); } if (info->next_index <= index && !IS_ERR(entry)) info->next_index = index + 1; return entry; } /* * shmem_free_swp - free some swap entries in a directory * * @dir: pointer to the directory * @edir: pointer after last entry of the directory */ static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir) { swp_entry_t *ptr; int freed = 0; for (ptr = dir; ptr < edir; ptr++) { if (ptr->val) { free_swap_and_cache(*ptr); *ptr = (swp_entry_t){0}; freed++; } } return freed; } static int shmem_map_and_free_swp(struct page *subdir, int offset, int limit, struct page ***dir) { swp_entry_t *ptr; int freed = 0; ptr = shmem_swp_map(subdir); for (; offset < limit; offset += LATENCY_LIMIT) { int size = limit - offset; if (size > LATENCY_LIMIT) size = LATENCY_LIMIT; freed += shmem_free_swp(ptr+offset, ptr+offset+size); if (need_resched()) { shmem_swp_unmap(ptr); if (*dir) { shmem_dir_unmap(*dir); *dir = NULL; } cond_resched(); ptr = shmem_swp_map(subdir); } } shmem_swp_unmap(ptr); return freed; } static void shmem_free_pages(struct list_head *next) { struct page *page; int freed = 0; do { page = container_of(next, struct page, lru); next = next->next; shmem_dir_free(page); freed++; if (freed >= LATENCY_LIMIT) { cond_resched(); freed = 0; } } while (next); } 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; unsigned long size; unsigned long limit; unsigned long stage; unsigned long diroff; struct page **dir; struct page *topdir; struct page *middir; struct page *subdir; swp_entry_t *ptr; LIST_HEAD(pages_to_free); long nr_pages_to_free = 0; long nr_swaps_freed = 0; int offset; int freed; int punch_hole = 0; inode->i_ctime = inode->i_mtime = CURRENT_TIME; idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; if (idx >= info->next_index) return; spin_lock(&info->lock); info->flags |= SHMEM_TRUNCATE; 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 && !punch_hole) { info->i_indirect = NULL; nr_pages_to_free++; list_add(&topdir->lru, &pages_to_free); } spin_unlock(&info->lock); if (info->swapped && idx < SHMEM_NR_DIRECT) { ptr = info->i_direct; size = limit; if (size > SHMEM_NR_DIRECT) size = SHMEM_NR_DIRECT; nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size); } /* * If there are no indirect blocks or we are punching a hole * below indirect blocks, nothing to be done. */ if (!topdir || (punch_hole && (limit <= SHMEM_NR_DIRECT))) goto done2; BUG_ON(limit <= SHMEM_NR_DIRECT); limit -= SHMEM_NR_DIRECT; idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; offset = idx % ENTRIES_PER_PAGE; idx -= offset; dir = shmem_dir_map(topdir); stage = ENTRIES_PER_PAGEPAGE/2; if (idx < ENTRIES_PER_PAGEPAGE/2) { middir = topdir; diroff = idx/ENTRIES_PER_PAGE; } else { dir += ENTRIES_PER_PAGE/2; dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; while (stage <= idx) stage += ENTRIES_PER_PAGEPAGE; middir = *dir; if (*dir) { diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; if (!diroff && !offset) { *dir = NULL; nr_pages_to_free++; list_add(&middir->lru, &pages_to_free); } shmem_dir_unmap(dir); dir = shmem_dir_map(middir); } else { diroff = 0; offset = 0; idx = stage; } } for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { if (unlikely(idx == stage)) { shmem_dir_unmap(dir); dir = shmem_dir_map(topdir) + ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; while (!*dir) { dir++; idx += ENTRIES_PER_PAGEPAGE; if (idx >= limit) goto done1; } stage = idx + ENTRIES_PER_PAGEPAGE; middir = *dir; *dir = NULL; nr_pages_to_free++; list_add(&middir->lru, &pages_to_free); shmem_dir_unmap(dir); cond_resched(); dir = shmem_dir_map(middir); diroff = 0; } subdir = dir[diroff]; if (subdir && page_private(subdir)) { size = limit - idx; if (size > ENTRIES_PER_PAGE) size = ENTRIES_PER_PAGE; freed = shmem_map_and_free_swp(subdir, offset, size, &dir); if (!dir) dir = shmem_dir_map(middir); nr_swaps_freed += freed; if (offset) spin_lock(&info->lock); set_page_private(subdir, page_private(subdir) - freed); if (offset) spin_unlock(&info->lock); if (!punch_hole) BUG_ON(page_private(subdir) > offset); } if (offset) offset = 0; else if (subdir && !page_private(subdir)) { dir[diroff] = NULL; nr_pages_to_free++; list_add(&subdir->lru, &pages_to_free); } } done1: shmem_dir_unmap(dir); done2: if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { /* * Call truncate_inode_pages again: racing shmem_unuse_inode * may have swizzled a page in from swap since vmtruncate or * generic_delete_inode did it, before we lowered next_index. * Also, though shmem_getpage checks i_size before adding to * cache, no recheck after: so fix the narrow window there too. */ truncate_inode_pages_range(inode->i_mapping, start, end); } spin_lock(&info->lock); info->flags &= ~SHMEM_TRUNCATE; info->swapped -= nr_swaps_freed; if (nr_pages_to_free) shmem_free_blocks(inode, nr_pages_to_free); shmem_recalc_inode(inode); spin_unlock(&info->lock); /* * Empty swap vector directory pages to be freed? */ if (!list_empty(&pages_to_free)) { pages_to_free.prev->next = NULL; shmem_free_pages(pages_to_free.next); } } 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; struct page *page = NULL; int error; if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { if (attr->ia_size < inode->i_size) { /* * If truncating down to a partial page, then * if that page is already allocated, hold it * in memory until the truncation is over, so * truncate_partial_page cannnot miss it were * it assigned to swap. */ if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { (void) shmem_getpage(inode, attr->ia_size>>PAGE_CACHE_SHIFT, &page, SGP_READ, NULL); } /* * Reset SHMEM_PAGEIN flag so that shmem_truncate can * detect if any pages might have been added to cache * after truncate_inode_pages. But we needn't bother * if it's being fully truncated to zero-length: the * nrpages check is efficient enough in that case. */ if (attr->ia_size) { struct shmem_inode_info *info = SHMEM_I(inode); spin_lock(&info->lock); info->flags &= ~SHMEM_PAGEIN; spin_unlock(&info->lock); } } } error = inode_change_ok(inode, attr); if (!error) error = inode_setattr(inode, attr); #ifdef CONFIG_TMPFS_POSIX_ACL if (!error && (attr->ia_valid & ATTR_MODE)) error = generic_acl_chmod(inode, &shmem_acl_ops); #endif if (page) page_cache_release(page); return error; } static void shmem_delete_inode(struct inode *inode) { struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); struct shmem_inode_info *info = SHMEM_I(inode); if (inode->i_op->truncate == shmem_truncate) { truncate_inode_pages(inode->i_mapping, 0); shmem_unacct_size(info->flags, inode->i_size); inode->i_size = 0; shmem_truncate(inode); if (!list_empty(&info->swaplist)) { spin_lock(&shmem_swaplist_lock); list_del_init(&info->swaplist); spin_unlock(&shmem_swaplist_lock); } } BUG_ON(inode->i_blocks); if (sbinfo->max_inodes) { spin_lock(&sbinfo->stat_lock); sbinfo->free_inodes++; spin_unlock(&sbinfo->stat_lock); } clear_inode(inode); } static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) { swp_entry_t *ptr; for (ptr = dir; ptr < edir; ptr++) { if (ptr->val == entry.val) return ptr - dir; } return -1; } static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) { struct inode *inode; unsigned long idx; unsigned long size; unsigned long limit; unsigned long stage; struct page **dir; struct page *subdir; swp_entry_t *ptr; int offset; idx = 0; ptr = info->i_direct; spin_lock(&info->lock); limit = info->next_index; size = limit; if (size > SHMEM_NR_DIRECT) size = SHMEM_NR_DIRECT; offset = shmem_find_swp(entry, ptr, ptr+size); if (offset >= 0) { shmem_swp_balance_unmap(); goto found; } if (!info->i_indirect) goto lost2; dir = shmem_dir_map(info->i_indirect); stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { if (unlikely(idx == stage)) { shmem_dir_unmap(dir-1); dir = shmem_dir_map(info->i_indirect) + ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; while (!*dir) { dir++; idx += ENTRIES_PER_PAGEPAGE; if (idx >= limit) goto lost1; } stage = idx + ENTRIES_PER_PAGEPAGE; subdir = *dir; shmem_dir_unmap(dir); dir = shmem_dir_map(subdir); } subdir = *dir; if (subdir && page_private(subdir)) { ptr = shmem_swp_map(subdir); size = limit - idx; if (size > ENTRIES_PER_PAGE) size = ENTRIES_PER_PAGE; offset = shmem_find_swp(entry, ptr, ptr+size); if (offset >= 0) { shmem_dir_unmap(dir); goto found; } shmem_swp_unmap(ptr); } } lost1: shmem_dir_unmap(dir-1); lost2: spin_unlock(&info->lock); return 0; found: idx += offset; inode = &info->vfs_inode; if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) { info->flags |= SHMEM_PAGEIN; shmem_swp_set(info, ptr + offset, 0); } shmem_swp_unmap(ptr); spin_unlock(&info->lock); /* * Decrement swap count even when the entry is left behind: * try_to_unuse will skip over mms, then reincrement count. */ swap_free(entry); return 1; } /* * shmem_unuse() search for an eventually swapped out shmem page. */ int shmem_unuse(swp_entry_t entry, struct page *page) { struct list_head *p, *next; struct shmem_inode_info *info; int found = 0; spin_lock(&shmem_swaplist_lock); list_for_each_safe(p, next, &shmem_swaplist) { info = list_entry(p, struct shmem_inode_info, swaplist); if (!info->swapped) list_del_init(&info->swaplist); else if (shmem_unuse_inode(info, entry, page)) { /* move head to start search for next from here */ list_move_tail(&shmem_swaplist, &info->swaplist); found = 1; break; } } spin_unlock(&shmem_swaplist_lock); return found; } /* * Move the page from the page cache to the swap cache. */ static int shmem_writepage(struct page *page, struct writeback_control *wbc) { struct shmem_inode_info *info; swp_entry_t *entry, swap; struct address_space *mapping; unsigned long index; struct inode *inode; BUG_ON(!PageLocked(page)); BUG_ON(page_mapped(page)); mapping = page->mapping; index = page->index; inode = mapping->host; info = SHMEM_I(inode); if (info->flags & VM_LOCKED) goto redirty; swap = get_swap_page(); if (!swap.val) goto redirty; spin_lock(&info->lock); shmem_recalc_inode(inode); if (index >= info->next_index) { BUG_ON(!(info->flags & SHMEM_TRUNCATE)); goto unlock; } entry = shmem_swp_entry(info, index, NULL); BUG_ON(!entry); BUG_ON(entry->val); if (move_to_swap_cache(page, swap) == 0) { shmem_swp_set(info, entry, swap.val); shmem_swp_unmap(entry); spin_unlock(&info->lock); if (list_empty(&info->swaplist)) { spin_lock(&shmem_swaplist_lock); /* move instead of add in case we're racing */ list_move_tail(&info->swaplist, &shmem_swaplist); spin_unlock(&shmem_swaplist_lock); } unlock_page(page); return 0; } shmem_swp_unmap(entry); unlock: spin_unlock(&info->lock); swap_free(swap); redirty: set_page_dirty(page); return AOP_WRITEPAGE_ACTIVATE; /* Return with the page locked */ } #ifdef CONFIG_NUMA static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) { char *nodelist = strchr(value, ':'); int err = 1; if (nodelist) { /* NUL-terminate policy string */ *nodelist++ = '\0'; if (nodelist_parse(nodelist, *policy_nodes)) goto out; } if (!strcmp(value, "default")) { *policy = MPOL_DEFAULT; /* Don't allow a nodelist */ if (!nodelist) err = 0; } else if (!strcmp(value, "prefer")) { *policy = MPOL_PREFERRED; /* Insist on a nodelist of one node only */ if (nodelist) { char *rest = nodelist; while (isdigit(*rest)) rest++; if (!*rest) err = 0; } } else if (!strcmp(value, "bind")) { *policy = MPOL_BIND; /* Insist on a nodelist */ if (nodelist) err = 0; } else if (!strcmp(value, "interleave")) { *policy = MPOL_INTERLEAVE; /* Default to nodes online if no nodelist */ if (!nodelist) *policy_nodes = node_online_map; err = 0; } out: /* Restore string for error message */ if (nodelist) *--nodelist = ':'; return err; } static struct page *shmem_swapin_async(struct shared_policy *p, swp_entry_t entry, unsigned long idx) { struct page *page; struct vm_area_struct pvma; /* Create a pseudo vma that just contains the policy */ memset(&pvma, 0, sizeof(struct vm_area_struct)); pvma.vm_end = PAGE_SIZE; pvma.vm_pgoff = idx; pvma.vm_policy = mpol_shared_policy_lookup(p, idx); page = read_swap_cache_async(entry, &pvma, 0); mpol_free(pvma.vm_policy); return page; } struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry, unsigned long idx) { struct shared_policy *p = &info->policy; int i, num; struct page *page; unsigned long offset; num = valid_swaphandles(entry, &offset); for (i = 0; i < num; offset++, i++) { page = shmem_swapin_async(p, swp_entry(swp_type(entry), offset), idx); if (!page) break; page_cache_release(page); } lru_add_drain(); /* Push any new pages onto the LRU now */ return shmem_swapin_async(p, entry, idx); } static struct page * shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info, unsigned long idx) { struct vm_area_struct pvma; struct page *page; memset(&pvma, 0, sizeof(struct vm_area_struct)); pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); pvma.vm_pgoff = idx; pvma.vm_end = PAGE_SIZE; page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0); mpol_free(pvma.vm_policy); return page; } #else static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) { return 1; } static inline struct page * shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx) { swapin_readahead(entry, 0, NULL); return read_swap_cache_async(entry, NULL, 0); } static inline struct page * shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx) { return alloc_page(gfp | __GFP_ZERO); } #endif /* * shmem_getpage - either get the page from swap or allocate a new one * * If we allocate a new one we do not mark it dirty. That's up to the * vm. If we swap it in we mark it dirty since we also free the swap * entry since a page cannot live in both the swap and page cache */ static int shmem_getpage(struct inode *inode, unsigned long idx, struct page **pagep, enum sgp_type sgp, int *type) { struct address_space *mapping = inode->i_mapping; struct shmem_inode_info *info = SHMEM_I(inode); struct shmem_sb_info *sbinfo; struct page *filepage = *pagep; struct page *swappage; swp_entry_t *entry; swp_entry_t swap; int error; if (idx >= SHMEM_MAX_INDEX) return -EFBIG; /* * Normally, filepage is NULL on entry, and either found * uptodate immediately, or allocated and zeroed, or read * in under swappage, which is then assigned to filepage. * But shmem_prepare_write passes in a locked filepage, * which may be found not uptodate by other callers too, * and may need to be copied from the swappage read in. */ repeat: if (!filepage) filepage = find_lock_page(mapping, idx); if (filepage && PageUptodate(filepage)) goto done; error = 0; if (sgp == SGP_QUICK) goto failed; spin_lock(&info->lock); shmem_recalc_inode(inode); entry = shmem_swp_alloc(info, idx, sgp); if (IS_ERR(entry)) { spin_unlock(&info->lock); error = PTR_ERR(entry); goto failed; } swap = *entry; if (swap.val) { /* Look it up and read it in.. */ swappage = lookup_swap_cache(swap); if (!swappage) { shmem_swp_unmap(entry); /* here we actually do the io */ if (type && *type == VM_FAULT_MINOR) { __count_vm_event(PGMAJFAULT); *type = VM_FAULT_MAJOR; } spin_unlock(&info->lock); swappage = shmem_swapin(info, swap, idx); if (!swappage) { spin_lock(&info->lock); entry = shmem_swp_alloc(info, idx, sgp); if (IS_ERR(entry)) error = PTR_ERR(entry); else { if (entry->val == swap.val) error = -ENOMEM; shmem_swp_unmap(entry); } spin_unlock(&info->lock); if (error) goto failed; goto repeat; } wait_on_page_locked(swappage); page_cache_release(swappage); goto repeat; } /* We have to do this with page locked to prevent races */ if (TestSetPageLocked(swappage)) { shmem_swp_unmap(entry); spin_unlock(&info->lock); wait_on_page_locked(swappage); page_cache_release(swappage); goto repeat; } if (PageWriteback(swappage)) { shmem_swp_unmap(entry); spin_unlock(&info->lock); wait_on_page_writeback(swappage); unlock_page(swappage); page_cache_release(swappage); goto repeat; } if (!PageUptodate(swappage)) { shmem_swp_unmap(entry); spin_unlock(&info->lock); unlock_page(swappage); page_cache_release(swappage); error = -EIO; goto failed; } if (filepage) { shmem_swp_set(info, entry, 0); shmem_swp_unmap(entry); delete_from_swap_cache(swappage); spin_unlock(&info->lock); copy_highpage(filepage, swappage); unlock_page(swappage); page_cache_release(swappage); flush_dcache_page(filepage); SetPageUptodate(filepage); set_page_dirty(filepage); swap_free(swap); } else if (!(error = move_from_swap_cache( swappage, idx, mapping))) { info->flags |= SHMEM_PAGEIN; shmem_swp_set(info, entry, 0); shmem_swp_unmap(entry); spin_unlock(&info->lock); filepage = swappage; swap_free(swap); } else { shmem_swp_unmap(entry); spin_unlock(&info->lock); unlock_page(swappage); page_cache_release(swappage); if (error == -ENOMEM) { /* let kswapd refresh zone for GFP_ATOMICs */ congestion_wait(WRITE, HZ/50); } goto repeat; } } else if (sgp == SGP_READ && !filepage) { shmem_swp_unmap(entry); filepage = find_get_page(mapping, idx); if (filepage && (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { spin_unlock(&info->lock); wait_on_page_locked(filepage); page_cache_release(filepage); filepage = NULL; goto repeat; } spin_unlock(&info->lock); } else { shmem_swp_unmap(entry); sbinfo = SHMEM_SB(inode->i_sb); if (sbinfo->max_blocks) { spin_lock(&sbinfo->stat_lock); if (sbinfo->free_blocks == 0 || shmem_acct_block(info->flags)) { spin_unlock(&sbinfo->stat_lock); spin_unlock(&info->lock); error = -ENOSPC; goto failed; } sbinfo->free_blocks--; inode->i_blocks += BLOCKS_PER_PAGE; spin_unlock(&sbinfo->stat_lock); } else if (shmem_acct_block(info->flags)) { spin_unlock(&info->lock); error = -ENOSPC; goto failed; } if (!filepage) { spin_unlock(&info->lock); filepage = shmem_alloc_page(mapping_gfp_mask(mapping), info, idx); if (!filepage) { shmem_unacct_blocks(info->flags, 1); shmem_free_blocks(inode, 1); error = -ENOMEM; goto failed; } spin_lock(&info->lock); entry = shmem_swp_alloc(info, idx, sgp); if (IS_ERR(entry)) error = PTR_ERR(entry); else { swap = *entry; shmem_swp_unmap(entry); } if (error || swap.val || 0 != add_to_page_cache_lru( filepage, mapping, idx, GFP_ATOMIC)) { spin_unlock(&info->lock); page_cache_release(filepage); shmem_unacct_blocks(info->flags, 1); shmem_free_blocks(inode, 1); filepage = NULL; if (error) goto failed; goto repeat; } info->flags |= SHMEM_PAGEIN; } info->alloced++; spin_unlock(&info->lock); flush_dcache_page(filepage); SetPageUptodate(filepage); } done: if (*pagep != filepage) { unlock_page(filepage); *pagep = filepage; } return 0; failed: if (*pagep != filepage) { unlock_page(filepage); page_cache_release(filepage); } return error; } struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type) { struct inode *inode = vma->vm_file->f_path.dentry->d_inode; struct page *page = NULL; unsigned long idx; int error; idx = (address - vma->vm_start) >> PAGE_SHIFT; idx += vma->vm_pgoff; idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT; if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode)) return NOPAGE_SIGBUS; error = shmem_getpage(inode, idx, &page, SGP_CACHE, type); if (error) return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS; mark_page_accessed(page); return page; } static int shmem_populate(struct vm_area_struct *vma, unsigned long addr, unsigned long len, pgprot_t prot, unsigned long pgoff, int nonblock) { struct inode *inode = vma->vm_file->f_path.dentry->d_inode; struct mm_struct *mm = vma->vm_mm; enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE; unsigned long size; size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size) return -EINVAL; while ((long) len > 0) { struct page *page = NULL; int err; /* * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE */ err = shmem_getpage(inode, pgoff, &page, sgp, NULL); if (err) return err; /* Page may still be null, but only if nonblock was set. */ if (page) { mark_page_accessed(page); err = install_page(mm, vma, addr, page, prot); if (err) { page_cache_release(page); return err; } } else if (vma->vm_flags & VM_NONLINEAR) { /* No page was found just because we can't read it in * now (being here implies nonblock != 0), but the page * may exist, so set the PTE to fault it in later. */ err = install_file_pte(mm, vma, addr, pgoff, prot); if (err) return err; } len -= PAGE_SIZE; addr += PAGE_SIZE; pgoff++; } return 0; } #ifdef CONFIG_NUMA int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) { struct inode *i = vma->vm_file->f_path.dentry->d_inode; return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); } struct mempolicy * shmem_get_policy(struct vm_area_struct *vma, unsigned long addr) { struct inode *i = vma->vm_file->f_path.dentry->d_inode; unsigned long idx; idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); } #endif int shmem_lock(struct file *file, int lock, struct user_struct *user) { struct inode *inode = file->f_path.dentry->d_inode; struct shmem_inode_info *info = SHMEM_I(inode); int retval = -ENOMEM; spin_lock(&info->lock); if (lock && !(info->flags & VM_LOCKED)) { if (!user_shm_lock(inode->i_size, user)) goto out_nomem; info->flags |= VM_LOCKED; } if (!lock && (info->flags & VM_LOCKED) && user) { user_shm_unlock(inode->i_size, user); info->flags &= ~VM_LOCKED; } retval = 0; out_nomem: spin_unlock(&info->lock); return retval; } int shmem_mmap(struct file *file, struct vm_area_struct *vma) { file_accessed(file); vma->vm_ops = &shmem_vm_ops; return 0; } static struct inode * shmem_get_inode(struct super_block *sb, int mode, dev_t dev) { struct inode *inode; struct shmem_inode_info *info; struct shmem_sb_info *sbinfo = SHMEM_SB(sb); if (sbinfo->max_inodes) { spin_lock(&sbinfo->stat_lock); if (!sbinfo->free_inodes) { spin_unlock(&sbinfo->stat_lock); return NULL; } sbinfo->free_inodes--; spin_unlock(&sbinfo->stat_lock); } inode = new_inode(sb); if (inode) { inode->i_mode = mode; inode->i_uid = current->fsuid; inode->i_gid = current->fsgid; inode->i_blocks = 0; inode->i_mapping->a_ops = &shmem_aops; inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; inode->i_generation = get_seconds(); info = SHMEM_I(inode); memset(info, 0, (char *)inode - (char *)info); spin_lock_init(&info->lock); INIT_LIST_HEAD(&info->swaplist); switch (mode & S_IFMT) { default: inode->i_op = &shmem_special_inode_operations; init_special_inode(inode, mode, dev); break; case S_IFREG: inode->i_op = &shmem_inode_operations; inode->i_fop = &shmem_file_operations; mpol_shared_policy_init(&info->policy, sbinfo->policy, &sbinfo->policy_nodes); break; case S_IFDIR: inc_nlink(inode); /* Some things misbehave if size == 0 on a directory */ inode->i_size = 2 * BOGO_DIRENT_SIZE; inode->i_op = &shmem_dir_inode_operations; inode->i_fop = &simple_dir_operations; break; case S_IFLNK: /* * Must not load anything in the rbtree, * mpol_free_shared_policy will not be called. */ mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, NULL); break; } } else if (sbinfo->max_inodes) { spin_lock(&sbinfo->stat_lock); sbinfo->free_inodes++; spin_unlock(&sbinfo->stat_lock); } return inode; } #ifdef CONFIG_TMPFS static const struct inode_operations shmem_symlink_inode_operations; static const struct inode_operations shmem_symlink_inline_operations; /* * Normally tmpfs makes no use of shmem_prepare_write, but it * lets a tmpfs file be used read-write below the loop driver. */ static int shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to) { struct inode *inode = page->mapping->host; return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL); } static ssize_t shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { struct inode *inode = file->f_path.dentry->d_inode; loff_t pos; unsigned long written; ssize_t err; if ((ssize_t) count < 0) return -EINVAL; if (!access_ok(VERIFY_READ, buf, count)) return -EFAULT; mutex_lock(&inode->i_mutex); pos = *ppos; written = 0; err = generic_write_checks(file, &pos, &count, 0); if (err || !count) goto out; err = remove_suid(file->f_path.dentry); if (err) goto out; inode->i_ctime = inode->i_mtime = CURRENT_TIME; do { struct page *page = NULL; unsigned long bytes, index, offset; char *kaddr; int left; offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ index = pos >> PAGE_CACHE_SHIFT; bytes = PAGE_CACHE_SIZE - offset; if (bytes > count) bytes = count; /* * We don't hold page lock across copy from user - * what would it guard against? - so no deadlock here. * But it still may be a good idea to prefault below. */ err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL); if (err) break; left = bytes; if (PageHighMem(page)) { volatile unsigned char dummy; __get_user(dummy, buf); __get_user(dummy, buf + bytes - 1); kaddr = kmap_atomic(page, KM_USER0); left = __copy_from_user_inatomic(kaddr + offset, buf, bytes); kunmap_atomic(kaddr, KM_USER0); } if (left) { kaddr = kmap(page); left = __copy_from_user(kaddr + offset, buf, bytes); kunmap(page); } written += bytes; count -= bytes; pos += bytes; buf += bytes; if (pos > inode->i_size) i_size_write(inode, pos); flush_dcache_page(page); set_page_dirty(page); mark_page_accessed(page); page_cache_release(page); if (left) { pos -= left; written -= left; err = -EFAULT; break; } /* * Our dirty pages are not counted in nr_dirty, * and we do not attempt to balance dirty pages. */ cond_resched(); } while (count); *ppos = pos; if (written) err = written; out: mutex_unlock(&inode->i_mutex); return err; } static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) { struct inode *inode = filp->f_path.dentry->d_inode; struct address_space *mapping = inode->i_mapping; unsigned long index, offset; index = *ppos >> PAGE_CACHE_SHIFT; offset = *ppos & ~PAGE_CACHE_MASK; for (;;) { struct page *page = NULL; unsigned long end_index, nr, ret; loff_t i_size = i_size_read(inode); end_index = i_size >> PAGE_CACHE_SHIFT; if (index > end_index) break; if (index == end_index) { nr = i_size & ~PAGE_CACHE_MASK; if (nr <= offset) break; } desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL); if (desc->error) { if (desc->error == -EINVAL) desc->error = 0; break; } /* * We must evaluate after, since reads (unlike writes) * are called without i_mutex protection against truncate */ nr = PAGE_CACHE_SIZE; i_size = i_size_read(inode); end_index = i_size >> PAGE_CACHE_SHIFT; if (index == end_index) { nr = i_size & ~PAGE_CACHE_MASK; if (nr <= offset) { if (page) page_cache_release(page); break; } } nr -= offset; if (page) { /* * If users can be writing to this page using arbitrary * virtual addresses, take care about potential aliasing * before reading the page on the kernel side. */ if (mapping_writably_mapped(mapping)) flush_dcache_page(page); /* * Mark the page accessed if we read the beginning. */ if (!offset) mark_page_accessed(page); } else { page = ZERO_PAGE(0); page_cache_get(page); } /* * Ok, we have the page, and it's up-to-date, so * now we can copy it to user space... * * The actor routine returns how many bytes were actually used.. * NOTE! This may not be the same as how much of a user buffer * we filled up (we may be padding etc), so we can only update * "pos" here (the actor routine has to update the user buffer * pointers and the remaining count). */ ret = actor(desc, page, offset, nr); offset += ret; index += offset >> PAGE_CACHE_SHIFT; offset &= ~PAGE_CACHE_MASK; page_cache_release(page); if (ret != nr || !desc->count) break; cond_resched(); } *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; file_accessed(filp); } static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) { read_descriptor_t desc; if ((ssize_t) count < 0) return -EINVAL; if (!access_ok(VERIFY_WRITE, buf, count)) return -EFAULT; if (!count) return 0; desc.written = 0; desc.count = count; desc.arg.buf = buf; desc.error = 0; do_shmem_file_read(filp, ppos, &desc, file_read_actor); if (desc.written) return desc.written; return desc.error; } static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos, size_t count, read_actor_t actor, void *target) { read_descriptor_t desc; if (!count) return 0; desc.written = 0; desc.count = count; desc.arg.data = target; desc.error = 0; do_shmem_file_read(in_file, ppos, &desc, actor); if (desc.written) return desc.written; return desc.error; } static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) { struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); buf->f_type = TMPFS_MAGIC; buf->f_bsize = PAGE_CACHE_SIZE; buf->f_namelen = NAME_MAX; spin_lock(&sbinfo->stat_lock); if (sbinfo->max_blocks) { buf->f_blocks = sbinfo->max_blocks; buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; } if (sbinfo->max_inodes) { buf->f_files = sbinfo->max_inodes; buf->f_ffree = sbinfo->free_inodes; } /* else leave those fields 0 like simple_statfs */ spin_unlock(&sbinfo->stat_lock); return 0; } /* * File creation. Allocate an inode, and we're done.. */ static int shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) { struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); int error = -ENOSPC; if (inode) { error = security_inode_init_security(inode, dir, NULL, NULL, NULL); if (error) { if (error != -EOPNOTSUPP) { iput(inode); return error; } } error = shmem_acl_init(inode, dir); if (error) { iput(inode); return error; } if (dir->i_mode & S_ISGID) { inode->i_gid = dir->i_gid; if (S_ISDIR(mode)) inode->i_mode |= S_ISGID; } dir->i_size += BOGO_DIRENT_SIZE; dir->i_ctime = dir->i_mtime = CURRENT_TIME; d_instantiate(dentry, inode); dget(dentry); /* Extra count - pin the dentry in core */ } return error; } static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) { int error; if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) return error; inc_nlink(dir); return 0; } static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd) { return shmem_mknod(dir, dentry, mode | S_IFREG, 0); } /* * Link a file.. */ static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) { struct inode *inode = old_dentry->d_inode; struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); /* * No ordinary (disk based) filesystem counts links as inodes; * but each new link needs a new dentry, pinning lowmem, and * tmpfs dentries cannot be pruned until they are unlinked. */ if (sbinfo->max_inodes) { spin_lock(&sbinfo->stat_lock); if (!sbinfo->free_inodes) { spin_unlock(&sbinfo->stat_lock); return -ENOSPC; } sbinfo->free_inodes--; spin_unlock(&sbinfo->stat_lock); } dir->i_size += BOGO_DIRENT_SIZE; inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; inc_nlink(inode); atomic_inc(&inode->i_count); /* New dentry reference */ dget(dentry); /* Extra pinning count for the created dentry */ d_instantiate(dentry, inode); return 0; } static int shmem_unlink(struct inode *dir, struct dentry *dentry) { struct inode *inode = dentry->d_inode; if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) { struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); if (sbinfo->max_inodes) { spin_lock(&sbinfo->stat_lock); sbinfo->free_inodes++; spin_unlock(&sbinfo->stat_lock); } } dir->i_size -= BOGO_DIRENT_SIZE; inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; drop_nlink(inode); dput(dentry); /* Undo the count from "create" - this does all the work */ return 0; } static int shmem_rmdir(struct inode *dir, struct dentry *dentry) { if (!simple_empty(dentry)) return -ENOTEMPTY; drop_nlink(dentry->d_inode); drop_nlink(dir); return shmem_unlink(dir, dentry); } /* * The VFS layer already does all the dentry stuff for rename, * we just have to decrement the usage count for the target if * it exists so that the VFS layer correctly free's it when it * gets overwritten. */ static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) { struct inode *inode = old_dentry->d_inode; int they_are_dirs = S_ISDIR(inode->i_mode); if (!simple_empty(new_dentry)) return -ENOTEMPTY; if (new_dentry->d_inode) { (void) shmem_unlink(new_dir, new_dentry); if (they_are_dirs) drop_nlink(old_dir); } else if (they_are_dirs) { drop_nlink(old_dir); inc_nlink(new_dir); } old_dir->i_size -= BOGO_DIRENT_SIZE; new_dir->i_size += BOGO_DIRENT_SIZE; old_dir->i_ctime = old_dir->i_mtime = new_dir->i_ctime = new_dir->i_mtime = inode->i_ctime = CURRENT_TIME; return 0; } static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) { int error; int len; struct inode *inode; struct page *page = NULL; char *kaddr; struct shmem_inode_info *info; len = strlen(symname) + 1; if (len > PAGE_CACHE_SIZE) return -ENAMETOOLONG; inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); if (!inode) return -ENOSPC; error = security_inode_init_security(inode, dir, NULL, NULL, NULL); if (error) { if (error != -EOPNOTSUPP) { iput(inode); return error; } error = 0; } info = SHMEM_I(inode); inode->i_size = len-1; if (len <= (char *)inode - (char *)info) { /* do it inline */ memcpy(info, symname, len); inode->i_op = &shmem_symlink_inline_operations; } else { error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); if (error) { iput(inode); return error; } inode->i_op = &shmem_symlink_inode_operations; kaddr = kmap_atomic(page, KM_USER0); memcpy(kaddr, symname, len); kunmap_atomic(kaddr, KM_USER0); set_page_dirty(page); page_cache_release(page); } if (dir->i_mode & S_ISGID) inode->i_gid = dir->i_gid; dir->i_size += BOGO_DIRENT_SIZE; dir->i_ctime = dir->i_mtime = CURRENT_TIME; d_instantiate(dentry, inode); dget(dentry); return 0; } static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) { nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); return NULL; } static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) { struct page *page = NULL; int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); return page; } static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) { if (!IS_ERR(nd_get_link(nd))) { struct page *page = cookie; kunmap(page); mark_page_accessed(page); page_cache_release(page); } } static const struct inode_operations shmem_symlink_inline_operations = { .readlink = generic_readlink, .follow_link = shmem_follow_link_inline, }; static const struct inode_operations shmem_symlink_inode_operations = { .truncate = shmem_truncate, .readlink = generic_readlink, .follow_link = shmem_follow_link, .put_link = shmem_put_link, }; #ifdef CONFIG_TMPFS_POSIX_ACL /** * Superblocks without xattr inode operations will get security.* xattr * support from the VFS "for free". As soon as we have any other xattrs * like ACLs, we also need to implement the security.* handlers at * filesystem level, though. */ static size_t shmem_xattr_security_list(struct inode *inode, char *list, size_t list_len, const char *name, size_t name_len) { return security_inode_listsecurity(inode, list, list_len); } static int shmem_xattr_security_get(struct inode *inode, const char *name, void *buffer, size_t size) { if (strcmp(name, "") == 0) return -EINVAL; return security_inode_getsecurity(inode, name, buffer, size, -EOPNOTSUPP); } static int shmem_xattr_security_set(struct inode *inode, const char *name, const void *value, size_t size, int flags) { if (strcmp(name, "") == 0) return -EINVAL; return security_inode_setsecurity(inode, name, value, size, flags); } static struct xattr_handler shmem_xattr_security_handler = { .prefix = XATTR_SECURITY_PREFIX, .list = shmem_xattr_security_list, .get = shmem_xattr_security_get, .set = shmem_xattr_security_set, }; static struct xattr_handler *shmem_xattr_handlers[] = { &shmem_xattr_acl_access_handler, &shmem_xattr_acl_default_handler, &shmem_xattr_security_handler, NULL }; #endif static struct dentry *shmem_get_parent(struct dentry *child) { return ERR_PTR(-ESTALE); } static int shmem_match(struct inode *ino, void *vfh) { __u32 *fh = vfh; __u64 inum = fh[2]; inum = (inum << 32) | fh[1]; return ino->i_ino == inum && fh[0] == ino->i_generation; } static struct dentry *shmem_get_dentry(struct super_block *sb, void *vfh) { struct dentry *de = NULL; struct inode *inode; __u32 *fh = vfh; __u64 inum = fh[2]; inum = (inum << 32) | fh[1]; inode = ilookup5(sb, (unsigned long)(inum+fh[0]), shmem_match, vfh); if (inode) { de = d_find_alias(inode); iput(inode); } return de? de: ERR_PTR(-ESTALE); } static struct dentry *shmem_decode_fh(struct super_block *sb, __u32 *fh, int len, int type, int (*acceptable)(void *context, struct dentry *de), void *context) { if (len < 3) return ERR_PTR(-ESTALE); return sb->s_export_op->find_exported_dentry(sb, fh, NULL, acceptable, context); } static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, int connectable) { struct inode *inode = dentry->d_inode; if (*len < 3) return 255; if (hlist_unhashed(&inode->i_hash)) { /* Unfortunately insert_inode_hash is not idempotent, * so as we hash inodes here rather than at creation * time, we need a lock to ensure we only try * to do it once */ static DEFINE_SPINLOCK(lock); spin_lock(&lock); if (hlist_unhashed(&inode->i_hash)) __insert_inode_hash(inode, inode->i_ino + inode->i_generation); spin_unlock(&lock); } fh[0] = inode->i_generation; fh[1] = inode->i_ino; fh[2] = ((__u64)inode->i_ino) >> 32; *len = 3; return 1; } static struct export_operations shmem_export_ops = { .get_parent = shmem_get_parent, .get_dentry = shmem_get_dentry, .encode_fh = shmem_encode_fh, .decode_fh = shmem_decode_fh, }; static int shmem_parse_options(char *options, int *mode, uid_t *uid, gid_t *gid, unsigned long *blocks, unsigned long *inodes, int *policy, nodemask_t *policy_nodes) { char *this_char, *value, *rest; while (options != NULL) { this_char = options; for (;;) { /* * NUL-terminate this option: unfortunately, * mount options form a comma-separated list, * but mpol's nodelist may also contain commas. */ options = strchr(options, ','); if (options == NULL) break; options++; if (!isdigit(*options)) { options[-1] = '\0'; break; } } if (!*this_char) continue; if ((value = strchr(this_char,'=')) != NULL) { *value++ = 0; } else { printk(KERN_ERR "tmpfs: No value for mount option '%s'\n", this_char); return 1; } if (!strcmp(this_char,"size")) { unsigned long long size; size = memparse(value,&rest); if (*rest == '%') { size <<= PAGE_SHIFT; size *= totalram_pages; do_div(size, 100); rest++; } if (*rest) goto bad_val; *blocks = size >> PAGE_CACHE_SHIFT; } else if (!strcmp(this_char,"nr_blocks")) { *blocks = memparse(value,&rest); if (*rest) goto bad_val; } else if (!strcmp(this_char,"nr_inodes")) { *inodes = memparse(value,&rest); if (*rest) goto bad_val; } else if (!strcmp(this_char,"mode")) { if (!mode) continue; *mode = simple_strtoul(value,&rest,8); if (*rest) goto bad_val; } else if (!strcmp(this_char,"uid")) { if (!uid) continue; *uid = simple_strtoul(value,&rest,0); if (*rest) goto bad_val; } else if (!strcmp(this_char,"gid")) { if (!gid) continue; *gid = simple_strtoul(value,&rest,0); if (*rest) goto bad_val; } else if (!strcmp(this_char,"mpol")) { if (shmem_parse_mpol(value,policy,policy_nodes)) goto bad_val; } else { printk(KERN_ERR "tmpfs: Bad mount option %s\n", this_char); return 1; } } return 0; bad_val: printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", value, this_char); return 1; } static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) { struct shmem_sb_info *sbinfo = SHMEM_SB(sb); unsigned long max_blocks = sbinfo->max_blocks; unsigned long max_inodes = sbinfo->max_inodes; int policy = sbinfo->policy; nodemask_t policy_nodes = sbinfo->policy_nodes; unsigned long blocks; unsigned long inodes; int error = -EINVAL; if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, &max_inodes, &policy, &policy_nodes)) return error; spin_lock(&sbinfo->stat_lock); blocks = sbinfo->max_blocks - sbinfo->free_blocks; inodes = sbinfo->max_inodes - sbinfo->free_inodes; if (max_blocks < blocks) goto out; if (max_inodes < inodes) goto out; /* * Those tests also disallow limited->unlimited while any are in * use, so i_blocks will always be zero when max_blocks is zero; * but we must separately disallow unlimited->limited, because * in that case we have no record of how much is already in use. */ if (max_blocks && !sbinfo->max_blocks) goto out; if (max_inodes && !sbinfo->max_inodes) goto out; error = 0; sbinfo->max_blocks = max_blocks; sbinfo->free_blocks = max_blocks - blocks; sbinfo->max_inodes = max_inodes; sbinfo->free_inodes = max_inodes - inodes; sbinfo->policy = policy; sbinfo->policy_nodes = policy_nodes; out: spin_unlock(&sbinfo->stat_lock); return error; } #endif static void shmem_put_super(struct super_block *sb) { kfree(sb->s_fs_info); sb->s_fs_info = NULL; } static int shmem_fill_super(struct super_block *sb, void *data, int silent) { struct inode *inode; struct dentry *root; int mode = S_IRWXUGO | S_ISVTX; uid_t uid = current->fsuid; gid_t gid = current->fsgid; int err = -ENOMEM; struct shmem_sb_info *sbinfo; unsigned long blocks = 0; unsigned long inodes = 0; int policy = MPOL_DEFAULT; nodemask_t policy_nodes = node_online_map; #ifdef CONFIG_TMPFS /* * Per default we only allow half of the physical ram per * tmpfs instance, limiting inodes to one per page of lowmem; * but the internal instance is left unlimited. */ if (!(sb->s_flags & MS_NOUSER)) { blocks = totalram_pages / 2; inodes = totalram_pages - totalhigh_pages; if (inodes > blocks) inodes = blocks; if (shmem_parse_options(data, &mode, &uid, &gid, &blocks, &inodes, &policy, &policy_nodes)) return -EINVAL; } sb->s_export_op = &shmem_export_ops; #else sb->s_flags |= MS_NOUSER; #endif /* Round up to L1_CACHE_BYTES to resist false sharing */ sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), L1_CACHE_BYTES), GFP_KERNEL); if (!sbinfo) return -ENOMEM; spin_lock_init(&sbinfo->stat_lock); sbinfo->max_blocks = blocks; sbinfo->free_blocks = blocks; sbinfo->max_inodes = inodes; sbinfo->free_inodes = inodes; sbinfo->policy = policy; sbinfo->policy_nodes = policy_nodes; sb->s_fs_info = sbinfo; sb->s_maxbytes = SHMEM_MAX_BYTES; sb->s_blocksize = PAGE_CACHE_SIZE; sb->s_blocksize_bits = PAGE_CACHE_SHIFT; sb->s_magic = TMPFS_MAGIC; sb->s_op = &shmem_ops; sb->s_time_gran = 1; #ifdef CONFIG_TMPFS_POSIX_ACL sb->s_xattr = shmem_xattr_handlers; sb->s_flags |= MS_POSIXACL; #endif inode = shmem_get_inode(sb, S_IFDIR | mode, 0); if (!inode) goto failed; inode->i_uid = uid; inode->i_gid = gid; root = d_alloc_root(inode); if (!root) goto failed_iput; sb->s_root = root; return 0; failed_iput: iput(inode); failed: shmem_put_super(sb); return err; } static struct kmem_cache *shmem_inode_cachep; static struct inode *shmem_alloc_inode(struct super_block *sb) { struct shmem_inode_info *p; p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); if (!p) return NULL; return &p->vfs_inode; } static void shmem_destroy_inode(struct inode *inode) { if ((inode->i_mode & S_IFMT) == S_IFREG) { /* only struct inode is valid if it's an inline symlink */ mpol_free_shared_policy(&SHMEM_I(inode)->policy); } shmem_acl_destroy_inode(inode); kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); } static void init_once(void *foo, struct kmem_cache *cachep, unsigned long flags) { struct shmem_inode_info *p = (struct shmem_inode_info *) foo; if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == SLAB_CTOR_CONSTRUCTOR) { inode_init_once(&p->vfs_inode); #ifdef CONFIG_TMPFS_POSIX_ACL p->i_acl = NULL; p->i_default_acl = NULL; #endif } } static int init_inodecache(void) { shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", sizeof(struct shmem_inode_info), 0, 0, init_once, NULL); if (shmem_inode_cachep == NULL) return -ENOMEM; return 0; } static void destroy_inodecache(void) { kmem_cache_destroy(shmem_inode_cachep); } static const struct address_space_operations shmem_aops = { .writepage = shmem_writepage, .set_page_dirty = __set_page_dirty_no_writeback, #ifdef CONFIG_TMPFS .prepare_write = shmem_prepare_write, .commit_write = simple_commit_write, #endif .migratepage = migrate_page, }; static const struct file_operations shmem_file_operations = { .mmap = shmem_mmap, #ifdef CONFIG_TMPFS .llseek = generic_file_llseek, .read = shmem_file_read, .write = shmem_file_write, .fsync = simple_sync_file, .sendfile = shmem_file_sendfile, #endif }; static const struct inode_operations shmem_inode_operations = { .truncate = shmem_truncate, .setattr = shmem_notify_change, .truncate_range = shmem_truncate_range, #ifdef CONFIG_TMPFS_POSIX_ACL .setxattr = generic_setxattr, .getxattr = generic_getxattr, .listxattr = generic_listxattr, .removexattr = generic_removexattr, .permission = shmem_permission, #endif }; static const struct inode_operations shmem_dir_inode_operations = { #ifdef CONFIG_TMPFS .create = shmem_create, .lookup = simple_lookup, .link = shmem_link, .unlink = shmem_unlink, .symlink = shmem_symlink, .mkdir = shmem_mkdir, .rmdir = shmem_rmdir, .mknod = shmem_mknod, .rename = shmem_rename, #endif #ifdef CONFIG_TMPFS_POSIX_ACL .setattr = shmem_notify_change, .setxattr = generic_setxattr, .getxattr = generic_getxattr, .listxattr = generic_listxattr, .removexattr = generic_removexattr, .permission = shmem_permission, #endif }; static const struct inode_operations shmem_special_inode_operations = { #ifdef CONFIG_TMPFS_POSIX_ACL .setattr = shmem_notify_change, .setxattr = generic_setxattr, .getxattr = generic_getxattr, .listxattr = generic_listxattr, .removexattr = generic_removexattr, .permission = shmem_permission, #endif }; static struct super_operations shmem_ops = { .alloc_inode = shmem_alloc_inode, .destroy_inode = shmem_destroy_inode, #ifdef CONFIG_TMPFS .statfs = shmem_statfs, .remount_fs = shmem_remount_fs, #endif .delete_inode = shmem_delete_inode, .drop_inode = generic_delete_inode, .put_super = shmem_put_super, }; static struct vm_operations_struct shmem_vm_ops = { .nopage = shmem_nopage, .populate = shmem_populate, #ifdef CONFIG_NUMA .set_policy = shmem_set_policy, .get_policy = shmem_get_policy, #endif }; static int shmem_get_sb(struct file_system_type *fs_type, int flags, const char *dev_name, void *data, struct vfsmount *mnt) { return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); } static struct file_system_type tmpfs_fs_type = { .owner = THIS_MODULE, .name = "tmpfs", .get_sb = shmem_get_sb, .kill_sb = kill_litter_super, }; static struct vfsmount *shm_mnt; static int __init init_tmpfs(void) { int error; error = init_inodecache(); if (error) goto out3; error = register_filesystem(&tmpfs_fs_type); if (error) { printk(KERN_ERR "Could not register tmpfs\n"); goto out2; } shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, tmpfs_fs_type.name, NULL); if (IS_ERR(shm_mnt)) { error = PTR_ERR(shm_mnt); printk(KERN_ERR "Could not kern_mount tmpfs\n"); goto out1; } return 0; out1: unregister_filesystem(&tmpfs_fs_type); out2: destroy_inodecache(); out3: shm_mnt = ERR_PTR(error); return error; } module_init(init_tmpfs) /* * shmem_file_setup - get an unlinked file living in tmpfs * * @name: name for dentry (to be seen in /proc/<pid>/maps * @size: size to be set for the file * */ struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) { int error; struct file *file; struct inode *inode; struct dentry *dentry, *root; struct qstr this; if (IS_ERR(shm_mnt)) return (void *)shm_mnt; if (size < 0 || size > SHMEM_MAX_BYTES) return ERR_PTR(-EINVAL); if (shmem_acct_size(flags, size)) return ERR_PTR(-ENOMEM); error = -ENOMEM; this.name = name; this.len = strlen(name); this.hash = 0; /* will go */ root = shm_mnt->mnt_root; dentry = d_alloc(root, &this); if (!dentry) goto put_memory; error = -ENFILE; file = get_empty_filp(); if (!file) goto put_dentry; error = -ENOSPC; inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); if (!inode) goto close_file; SHMEM_I(inode)->flags = flags & VM_ACCOUNT; d_instantiate(dentry, inode); inode->i_size = size; inode->i_nlink = 0; /* It is unlinked */ file->f_path.mnt = mntget(shm_mnt); file->f_path.dentry = dentry; file->f_mapping = inode->i_mapping; file->f_op = &shmem_file_operations; file->f_mode = FMODE_WRITE | FMODE_READ; return file; close_file: put_filp(file); put_dentry: dput(dentry); put_memory: shmem_unacct_size(flags, size); return ERR_PTR(error); } /* * shmem_zero_setup - setup a shared anonymous mapping * * @vma: the vma to be mmapped is prepared by do_mmap_pgoff */ int shmem_zero_setup(struct vm_area_struct *vma) { struct file *file; loff_t size = vma->vm_end - vma->vm_start; file = shmem_file_setup("dev/zero", size, vma->vm_flags); if (IS_ERR(file)) return PTR_ERR(file); if (vma->vm_file) fput(vma->vm_file); vma->vm_file = file; vma->vm_ops = &shmem_vm_ops; return 0; }