/* * 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 * Copyright (c) 2004 Red Hat, Inc., James Morris * * tiny-shmem: * Copyright (c) 2004, 2008 Matt Mackall * * This file is released under the GPL. */ #include #include #include #include #include #include #include #include #include #include static struct vfsmount *shm_mnt; #ifdef CONFIG_SHMEM /* * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * The maximum size of a shmem/tmpfs file is limited by the maximum size of * its triple-indirect swap vector - see illustration at shmem_swp_entry(). * * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel, * but one eighth of that on a 64-bit kernel. With 8kB page size, maximum * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel, * MAX_LFS_FILESIZE being then more restrictive than swap vector layout. * * We use / and * instead of shifts in the definitions below, so that the swap * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE. */ #define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) #define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) #define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) #define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT) #define SHMEM_MAX_BYTES min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE) #define SHMEM_MAX_INDEX ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT)) #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) #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_READ, /* don't exceed i_size, don't allocate page */ SGP_CACHE, /* don't exceed i_size, may allocate page */ SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */ SGP_WRITE, /* may exceed i_size, may allocate page */ }; #ifdef CONFIG_TMPFS static unsigned long shmem_default_max_blocks(void) { return totalram_pages / 2; } static unsigned long shmem_default_max_inodes(void) { return min(totalram_pages - totalhigh_pages, totalram_pages / 2); } #endif 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. * * Mobility flags are masked out as swap vectors cannot move */ return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO, 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_NORESERVE) ? 0 : security_vm_enough_memory_kern(VM_ACCT(size)); } static inline void shmem_unacct_size(unsigned long flags, loff_t size) { if (!(flags & VM_NORESERVE)) 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_NORESERVE) ? security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0; } static inline void shmem_unacct_blocks(unsigned long flags, long pages) { if (flags & VM_NORESERVE) vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); } static const 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 const 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_AND_WRITEBACK | BDI_CAP_SWAP_BACKED, .unplug_io_fn = default_unplug_io_fn, }; static LIST_HEAD(shmem_swaplist); static DEFINE_MUTEX(shmem_swaplist_mutex); static void shmem_free_blocks(struct inode *inode, long pages) { struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); if (sbinfo->max_blocks) { percpu_counter_add(&sbinfo->used_blocks, -pages); spin_lock(&inode->i_lock); inode->i_blocks -= pages*BLOCKS_PER_PAGE; spin_unlock(&inode->i_lock); } } static int shmem_reserve_inode(struct super_block *sb) { 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 -ENOSPC; } sbinfo->free_inodes--; spin_unlock(&sbinfo->stat_lock); } return 0; } static void shmem_free_inode(struct super_block *sb) { struct shmem_sb_info *sbinfo = SHMEM_SB(sb); if (sbinfo->max_inodes) { spin_lock(&sbinfo->stat_lock); sbinfo->free_inodes++; 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. * @info: info structure for the inode * @index: index of the page to find * @sgp: check and recheck i_size? skip allocation? * * If the entry does not exist, allocate it. */ 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 used_blocks against 1 less max_blocks, 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) { if (percpu_counter_compare(&sbinfo->used_blocks, (sbinfo->max_blocks - 1)) > 0) return ERR_PTR(-ENOSPC); percpu_counter_inc(&sbinfo->used_blocks); spin_lock(&inode->i_lock); inode->i_blocks += BLOCKS_PER_PAGE; spin_unlock(&inode->i_lock); } spin_unlock(&info->lock); page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping)); 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 * @punch_lock: pointer to spinlock when needed for the holepunch case */ static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir, spinlock_t *punch_lock) { spinlock_t *punch_unlock = NULL; swp_entry_t *ptr; int freed = 0; for (ptr = dir; ptr < edir; ptr++) { if (ptr->val) { if (unlikely(punch_lock)) { punch_unlock = punch_lock; punch_lock = NULL; spin_lock(punch_unlock); if (!ptr->val) continue; } free_swap_and_cache(*ptr); *ptr = (swp_entry_t){0}; freed++; } } if (punch_unlock) spin_unlock(punch_unlock); return freed; } static int shmem_map_and_free_swp(struct page *subdir, int offset, int limit, struct page ***dir, spinlock_t *punch_lock) { 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, punch_lock); 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; spinlock_t *needs_lock; spinlock_t *punch_lock; unsigned long upper_limit; 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; upper_limit = SHMEM_MAX_INDEX; info->next_index = idx; needs_lock = NULL; punch_hole = 0; } else { if (end + 1 >= inode->i_size) { /* we may free a little more */ limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; upper_limit = SHMEM_MAX_INDEX; } else { limit = (end + 1) >> PAGE_CACHE_SHIFT; upper_limit = limit; } needs_lock = &info->lock; 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, needs_lock); } /* * If there are no indirect blocks or we are punching a hole * below indirect blocks, nothing to be done. */ if (!topdir || limit <= SHMEM_NR_DIRECT) goto done2; /* * The truncation case has already dropped info->lock, and we're safe * because i_size and next_index have already been lowered, preventing * access beyond. But in the punch_hole case, we still need to take * the lock when updating the swap directory, because there might be * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or * shmem_writepage. However, whenever we find we can remove a whole * directory page (not at the misaligned start or end of the range), * we first NULLify its pointer in the level above, and then have no * need to take the lock when updating its contents: needs_lock and * punch_lock (either pointing to info->lock or NULL) manage this. */ upper_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 && upper_limit >= stage) { if (needs_lock) { spin_lock(needs_lock); *dir = NULL; spin_unlock(needs_lock); needs_lock = NULL; } else *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; if (punch_hole) needs_lock = &info->lock; if (upper_limit >= stage) { if (needs_lock) { spin_lock(needs_lock); *dir = NULL; spin_unlock(needs_lock); needs_lock = NULL; } else *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; } punch_lock = needs_lock; subdir = dir[diroff]; if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) { if (needs_lock) { spin_lock(needs_lock); dir[diroff] = NULL; spin_unlock(needs_lock); punch_lock = NULL; } else dir[diroff] = NULL; nr_pages_to_free++; list_add(&subdir->lru, &pages_to_free); } if (subdir && page_private(subdir) /* has swap entries */) { size = limit - idx; if (size > ENTRIES_PER_PAGE) size = ENTRIES_PER_PAGE; freed = shmem_map_and_free_swp(subdir, offset, size, &dir, punch_lock); if (!dir) dir = shmem_dir_map(middir); nr_swaps_freed += freed; if (offset || punch_lock) { spin_lock(&info->lock); set_page_private(subdir, page_private(subdir) - freed); spin_unlock(&info->lock); } else BUG_ON(page_private(subdir) != freed); } offset = 0; } 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 * truncate_pagecache 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. * * Recalling truncate_inode_pages_range and unmap_mapping_range * every time for punch_hole (which never got a chance to clear * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive, * yet hardly ever necessary: try to optimize them out later. */ truncate_inode_pages_range(inode->i_mapping, start, end); if (punch_hole) unmap_mapping_range(inode->i_mapping, start, end - start, 1); } 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 int shmem_notify_change(struct dentry *dentry, struct iattr *attr) { struct inode *inode = dentry->d_inode; loff_t newsize = attr->ia_size; int error; error = inode_change_ok(inode, attr); if (error) return error; if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE) && newsize != inode->i_size) { struct page *page = NULL; if (newsize < 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 (newsize & (PAGE_CACHE_SIZE-1)) { (void) shmem_getpage(inode, newsize >> PAGE_CACHE_SHIFT, &page, SGP_READ, NULL); if (page) unlock_page(page); } /* * 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 (newsize) { struct shmem_inode_info *info = SHMEM_I(inode); spin_lock(&info->lock); info->flags &= ~SHMEM_PAGEIN; spin_unlock(&info->lock); } } /* XXX(truncate): truncate_setsize should be called last */ truncate_setsize(inode, newsize); if (page) page_cache_release(page); shmem_truncate_range(inode, newsize, (loff_t)-1); } setattr_copy(inode, attr); #ifdef CONFIG_TMPFS_POSIX_ACL if (attr->ia_valid & ATTR_MODE) error = generic_acl_chmod(inode); #endif return error; } static void shmem_evict_inode(struct inode *inode) { struct shmem_inode_info *info = SHMEM_I(inode); if (inode->i_mapping->a_ops == &shmem_aops) { truncate_inode_pages(inode->i_mapping, 0); shmem_unacct_size(info->flags, inode->i_size); inode->i_size = 0; shmem_truncate_range(inode, 0, (loff_t)-1); if (!list_empty(&info->swaplist)) { mutex_lock(&shmem_swaplist_mutex); list_del_init(&info->swaplist); mutex_unlock(&shmem_swaplist_mutex); } } BUG_ON(inode->i_blocks); shmem_free_inode(inode->i_sb); end_writeback(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; int error; idx = 0; ptr = info->i_direct; spin_lock(&info->lock); if (!info->swapped) { list_del_init(&info->swaplist); goto lost2; } 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) 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); if (cond_resched_lock(&info->lock)) { /* check it has not been truncated */ if (limit > info->next_index) { limit = info->next_index; if (idx >= limit) goto lost2; } } 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); shmem_swp_unmap(ptr); if (offset >= 0) { shmem_dir_unmap(dir); goto found; } } } lost1: shmem_dir_unmap(dir-1); lost2: spin_unlock(&info->lock); return 0; found: idx += offset; inode = igrab(&info->vfs_inode); spin_unlock(&info->lock); /* * Move _head_ to start search for next from here. * But be careful: shmem_evict_inode checks list_empty without taking * mutex, and there's an instant in list_move_tail when info->swaplist * would appear empty, if it were the only one on shmem_swaplist. We * could avoid doing it if inode NULL; or use this minor optimization. */ if (shmem_swaplist.next != &info->swaplist) list_move_tail(&shmem_swaplist, &info->swaplist); mutex_unlock(&shmem_swaplist_mutex); error = 1; if (!inode) goto out; /* * Charge page using GFP_KERNEL while we can wait. * Charged back to the user(not to caller) when swap account is used. * add_to_page_cache() will be called with GFP_NOWAIT. */ error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); if (error) goto out; error = radix_tree_preload(GFP_KERNEL); if (error) { mem_cgroup_uncharge_cache_page(page); goto out; } error = 1; spin_lock(&info->lock); ptr = shmem_swp_entry(info, idx, NULL); if (ptr && ptr->val == entry.val) { error = add_to_page_cache_locked(page, inode->i_mapping, idx, GFP_NOWAIT); /* does mem_cgroup_uncharge_cache_page on error */ } else /* we must compensate for our precharge above */ mem_cgroup_uncharge_cache_page(page); if (error == -EEXIST) { struct page *filepage = find_get_page(inode->i_mapping, idx); error = 1; if (filepage) { /* * There might be a more uptodate page coming down * from a stacked writepage: forget our swappage if so. */ if (PageUptodate(filepage)) error = 0; page_cache_release(filepage); } } if (!error) { delete_from_swap_cache(page); set_page_dirty(page); info->flags |= SHMEM_PAGEIN; shmem_swp_set(info, ptr, 0); swap_free(entry); error = 1; /* not an error, but entry was found */ } if (ptr) shmem_swp_unmap(ptr); spin_unlock(&info->lock); radix_tree_preload_end(); out: unlock_page(page); page_cache_release(page); iput(inode); /* allows for NULL */ return error; } /* * 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; mutex_lock(&shmem_swaplist_mutex); list_for_each_safe(p, next, &shmem_swaplist) { info = list_entry(p, struct shmem_inode_info, swaplist); found = shmem_unuse_inode(info, entry, page); cond_resched(); if (found) goto out; } mutex_unlock(&shmem_swaplist_mutex); /* * Can some race bring us here? We've been holding page lock, * so I think not; but would rather try again later than BUG() */ unlock_page(page); page_cache_release(page); out: return (found < 0) ? found : 0; } /* * 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)); mapping = page->mapping; index = page->index; inode = mapping->host; info = SHMEM_I(inode); if (info->flags & VM_LOCKED) goto redirty; if (!total_swap_pages) goto redirty; /* * shmem_backing_dev_info's capabilities prevent regular writeback or * sync from ever calling shmem_writepage; but a stacking filesystem * may use the ->writepage of its underlying filesystem, in which case * tmpfs should write out to swap only in response to memory pressure, * and not for the writeback threads or sync. However, in those cases, * we do still want to check if there's a redundant swappage to be * discarded. */ if (wbc->for_reclaim) swap = get_swap_page(); else swap.val = 0; spin_lock(&info->lock); if (index >= info->next_index) { BUG_ON(!(info->flags & SHMEM_TRUNCATE)); goto unlock; } entry = shmem_swp_entry(info, index, NULL); if (entry->val) { /* * The more uptodate page coming down from a stacked * writepage should replace our old swappage. */ free_swap_and_cache(*entry); shmem_swp_set(info, entry, 0); } shmem_recalc_inode(inode); if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { remove_from_page_cache(page); shmem_swp_set(info, entry, swap.val); shmem_swp_unmap(entry); if (list_empty(&info->swaplist)) inode = igrab(inode); else inode = NULL; spin_unlock(&info->lock); swap_shmem_alloc(swap); BUG_ON(page_mapped(page)); page_cache_release(page); /* pagecache ref */ swap_writepage(page, wbc); if (inode) { mutex_lock(&shmem_swaplist_mutex); /* move instead of add in case we're racing */ list_move_tail(&info->swaplist, &shmem_swaplist); mutex_unlock(&shmem_swaplist_mutex); iput(inode); } return 0; } shmem_swp_unmap(entry); unlock: spin_unlock(&info->lock); /* * add_to_swap_cache() doesn't return -EEXIST, so we can safely * clear SWAP_HAS_CACHE flag. */ swapcache_free(swap, NULL); redirty: set_page_dirty(page); if (wbc->for_reclaim) return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */ unlock_page(page); return 0; } #ifdef CONFIG_NUMA #ifdef CONFIG_TMPFS static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol) { char buffer[64]; if (!mpol || mpol->mode == MPOL_DEFAULT) return; /* show nothing */ mpol_to_str(buffer, sizeof(buffer), mpol, 1); seq_printf(seq, ",mpol=%s", buffer); } static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) { struct mempolicy *mpol = NULL; if (sbinfo->mpol) { spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */ mpol = sbinfo->mpol; mpol_get(mpol); spin_unlock(&sbinfo->stat_lock); } return mpol; } #endif /* CONFIG_TMPFS */ static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, struct shmem_inode_info *info, unsigned long idx) { struct mempolicy mpol, *spol; struct vm_area_struct pvma; struct page *page; spol = mpol_cond_copy(&mpol, mpol_shared_policy_lookup(&info->policy, idx)); /* Create a pseudo vma that just contains the policy */ pvma.vm_start = 0; pvma.vm_pgoff = idx; pvma.vm_ops = NULL; pvma.vm_policy = spol; page = swapin_readahead(entry, gfp, &pvma, 0); return page; } static struct page *shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info, unsigned long idx) { struct vm_area_struct pvma; /* Create a pseudo vma that just contains the policy */ pvma.vm_start = 0; pvma.vm_pgoff = idx; pvma.vm_ops = NULL; pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); /* * alloc_page_vma() will drop the shared policy reference */ return alloc_page_vma(gfp, &pvma, 0); } #else /* !CONFIG_NUMA */ #ifdef CONFIG_TMPFS static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p) { } #endif /* CONFIG_TMPFS */ static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp, struct shmem_inode_info *info, unsigned long idx) { return swapin_readahead(entry, gfp, NULL, 0); } static inline struct page *shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info, unsigned long idx) { return alloc_page(gfp); } #endif /* CONFIG_NUMA */ #if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS) static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo) { return NULL; } #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; struct page *prealloc_page = NULL; swp_entry_t *entry; swp_entry_t swap; gfp_t gfp; int error; if (idx >= SHMEM_MAX_INDEX) return -EFBIG; if (type) *type = 0; /* * 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_readpage (required for splice) 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; gfp = mapping_gfp_mask(mapping); if (!filepage) { /* * Try to preload while we can wait, to not make a habit of * draining atomic reserves; but don't latch on to this cpu. */ error = radix_tree_preload(gfp & ~__GFP_HIGHMEM); if (error) goto failed; radix_tree_preload_end(); if (sgp != SGP_READ && !prealloc_page) { /* We don't care if this fails */ prealloc_page = shmem_alloc_page(gfp, info, idx); if (prealloc_page) { if (mem_cgroup_cache_charge(prealloc_page, current->mm, GFP_KERNEL)) { page_cache_release(prealloc_page); prealloc_page = NULL; } } } } error = 0; 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_MAJOR)) { __count_vm_event(PGMAJFAULT); *type |= VM_FAULT_MAJOR; } spin_unlock(&info->lock); swappage = shmem_swapin(swap, gfp, info, 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 (!trylock_page(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 = add_to_page_cache_locked(swappage, mapping, idx, GFP_NOWAIT))) { info->flags |= SHMEM_PAGEIN; shmem_swp_set(info, entry, 0); shmem_swp_unmap(entry); delete_from_swap_cache(swappage); spin_unlock(&info->lock); filepage = swappage; set_page_dirty(filepage); swap_free(swap); } else { shmem_swp_unmap(entry); spin_unlock(&info->lock); if (error == -ENOMEM) { /* * reclaim from proper memory cgroup and * call memcg's OOM if needed. */ error = mem_cgroup_shmem_charge_fallback( swappage, current->mm, gfp); if (error) { unlock_page(swappage); page_cache_release(swappage); goto failed; } } unlock_page(swappage); page_cache_release(swappage); goto repeat; } } else if (sgp == SGP_READ && !filepage) { shmem_swp_unmap(entry); filepage = find_get_page(mapping, idx); if (filepage && (!PageUptodate(filepage) || !trylock_page(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) { if ((percpu_counter_compare(&sbinfo->used_blocks, sbinfo->max_blocks) > 0) || shmem_acct_block(info->flags)) { spin_unlock(&info->lock); error = -ENOSPC; goto failed; } percpu_counter_inc(&sbinfo->used_blocks); spin_lock(&inode->i_lock); inode->i_blocks += BLOCKS_PER_PAGE; spin_unlock(&inode->i_lock); } else if (shmem_acct_block(info->flags)) { spin_unlock(&info->lock); error = -ENOSPC; goto failed; } if (!filepage) { int ret; if (!prealloc_page) { spin_unlock(&info->lock); filepage = shmem_alloc_page(gfp, info, idx); if (!filepage) { shmem_unacct_blocks(info->flags, 1); shmem_free_blocks(inode, 1); error = -ENOMEM; goto failed; } SetPageSwapBacked(filepage); /* * Precharge page while we can wait, compensate * after */ error = mem_cgroup_cache_charge(filepage, current->mm, GFP_KERNEL); if (error) { page_cache_release(filepage); shmem_unacct_blocks(info->flags, 1); shmem_free_blocks(inode, 1); filepage = NULL; goto failed; } spin_lock(&info->lock); } else { filepage = prealloc_page; prealloc_page = NULL; SetPageSwapBacked(filepage); } entry = shmem_swp_alloc(info, idx, sgp); if (IS_ERR(entry)) error = PTR_ERR(entry); else { swap = *entry; shmem_swp_unmap(entry); } ret = error || swap.val; if (ret) mem_cgroup_uncharge_cache_page(filepage); else ret = add_to_page_cache_lru(filepage, mapping, idx, GFP_NOWAIT); /* * At add_to_page_cache_lru() failure, uncharge will * be done automatically. */ if (ret) { 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); clear_highpage(filepage); flush_dcache_page(filepage); SetPageUptodate(filepage); if (sgp == SGP_DIRTY) set_page_dirty(filepage); } done: *pagep = filepage; error = 0; goto out; failed: if (*pagep != filepage) { unlock_page(filepage); page_cache_release(filepage); } out: if (prealloc_page) { mem_cgroup_uncharge_cache_page(prealloc_page); page_cache_release(prealloc_page); } return error; } static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf) { struct inode *inode = vma->vm_file->f_path.dentry->d_inode; int error; int ret; if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) return VM_FAULT_SIGBUS; error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); if (error) return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); return ret | VM_FAULT_LOCKED; } #ifdef CONFIG_NUMA static 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); } static 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; mapping_set_unevictable(file->f_mapping); } if (!lock && (info->flags & VM_LOCKED) && user) { user_shm_unlock(inode->i_size, user); info->flags &= ~VM_LOCKED; mapping_clear_unevictable(file->f_mapping); scan_mapping_unevictable_pages(file->f_mapping); } retval = 0; out_nomem: spin_unlock(&info->lock); return retval; } static int shmem_mmap(struct file *file, struct vm_area_struct *vma) { file_accessed(file); vma->vm_ops = &shmem_vm_ops; vma->vm_flags |= VM_CAN_NONLINEAR; return 0; } static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir, int mode, dev_t dev, unsigned long flags) { struct inode *inode; struct shmem_inode_info *info; struct shmem_sb_info *sbinfo = SHMEM_SB(sb); if (shmem_reserve_inode(sb)) return NULL; inode = new_inode(sb); if (inode) { inode->i_ino = get_next_ino(); inode_init_owner(inode, dir, mode); inode->i_blocks = 0; 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); info->flags = flags & VM_NORESERVE; INIT_LIST_HEAD(&info->swaplist); cache_no_acl(inode); switch (mode & S_IFMT) { default: inode->i_op = &shmem_special_inode_operations; init_special_inode(inode, mode, dev); break; case S_IFREG: inode->i_mapping->a_ops = &shmem_aops; inode->i_op = &shmem_inode_operations; inode->i_fop = &shmem_file_operations; mpol_shared_policy_init(&info->policy, shmem_get_sbmpol(sbinfo)); 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, NULL); break; } } else shmem_free_inode(sb); 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 avoids the use of shmem_readpage and shmem_write_begin; * but providing them allows a tmpfs file to be used for splice, sendfile, and * below the loop driver, in the generic fashion that many filesystems support. */ static int shmem_readpage(struct file *file, struct page *page) { struct inode *inode = page->mapping->host; int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL); unlock_page(page); return error; } static int shmem_write_begin(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned flags, struct page **pagep, void **fsdata) { struct inode *inode = mapping->host; pgoff_t index = pos >> PAGE_CACHE_SHIFT; *pagep = NULL; return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL); } static int shmem_write_end(struct file *file, struct address_space *mapping, loff_t pos, unsigned len, unsigned copied, struct page *page, void *fsdata) { struct inode *inode = mapping->host; if (pos + copied > inode->i_size) i_size_write(inode, pos + copied); set_page_dirty(page); unlock_page(page); page_cache_release(page); return copied; } 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; enum sgp_type sgp = SGP_READ; /* * Might this read be for a stacking filesystem? Then when reading * holes of a sparse file, we actually need to allocate those pages, * and even mark them dirty, so it cannot exceed the max_blocks limit. */ if (segment_eq(get_fs(), KERNEL_DS)) sgp = SGP_DIRTY; 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, NULL); if (desc->error) { if (desc->error == -EINVAL) desc->error = 0; break; } if (page) unlock_page(page); /* * 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_aio_read(struct kiocb *iocb, const struct iovec *iov, unsigned long nr_segs, loff_t pos) { struct file *filp = iocb->ki_filp; ssize_t retval; unsigned long seg; size_t count; loff_t *ppos = &iocb->ki_pos; retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE); if (retval) return retval; for (seg = 0; seg < nr_segs; seg++) { read_descriptor_t desc; desc.written = 0; desc.arg.buf = iov[seg].iov_base; desc.count = iov[seg].iov_len; if (desc.count == 0) continue; desc.error = 0; do_shmem_file_read(filp, ppos, &desc, file_read_actor); retval += desc.written; if (desc.error) { retval = retval ?: desc.error; break; } if (desc.count > 0) break; } return retval; } 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; if (sbinfo->max_blocks) { buf->f_blocks = sbinfo->max_blocks; buf->f_bavail = buf->f_bfree = sbinfo->max_blocks - percpu_counter_sum(&sbinfo->used_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 */ 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; int error = -ENOSPC; inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE); if (inode) { error = security_inode_init_security(inode, dir, NULL, NULL, NULL); if (error) { if (error != -EOPNOTSUPP) { iput(inode); return error; } } #ifdef CONFIG_TMPFS_POSIX_ACL error = generic_acl_init(inode, dir); if (error) { iput(inode); return error; } #else error = 0; #endif 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; int ret; /* * 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. */ ret = shmem_reserve_inode(inode->i_sb); if (ret) goto out; dir->i_size += BOGO_DIRENT_SIZE; inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; inc_nlink(inode); ihold(inode); /* New dentry reference */ dget(dentry); /* Extra pinning count for the created dentry */ d_instantiate(dentry, inode); out: return ret; } 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)) shmem_free_inode(inode->i_sb); 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, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE); 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_mapping->a_ops = &shmem_aops; 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); unlock_page(page); page_cache_release(page); } 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)); if (page) unlock_page(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 = { .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 dentry *dentry, char *list, size_t list_len, const char *name, size_t name_len, int handler_flags) { return security_inode_listsecurity(dentry->d_inode, list, list_len); } static int shmem_xattr_security_get(struct dentry *dentry, const char *name, void *buffer, size_t size, int handler_flags) { if (strcmp(name, "") == 0) return -EINVAL; return xattr_getsecurity(dentry->d_inode, name, buffer, size); } static int shmem_xattr_security_set(struct dentry *dentry, const char *name, const void *value, size_t size, int flags, int handler_flags) { if (strcmp(name, "") == 0) return -EINVAL; return security_inode_setsecurity(dentry->d_inode, name, value, size, flags); } static const 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 const struct xattr_handler *shmem_xattr_handlers[] = { &generic_acl_access_handler, &generic_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_fh_to_dentry(struct super_block *sb, struct fid *fid, int fh_len, int fh_type) { struct inode *inode; struct dentry *dentry = NULL; u64 inum = fid->raw[2]; inum = (inum << 32) | fid->raw[1]; if (fh_len < 3) return NULL; inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]), shmem_match, fid->raw); if (inode) { dentry = d_find_alias(inode); iput(inode); } return dentry; } 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 (inode_unhashed(inode)) { /* 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 (inode_unhashed(inode)) __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 const struct export_operations shmem_export_ops = { .get_parent = shmem_get_parent, .encode_fh = shmem_encode_fh, .fh_to_dentry = shmem_fh_to_dentry, }; static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo, bool remount) { 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; sbinfo->max_blocks = DIV_ROUND_UP(size, PAGE_CACHE_SIZE); } else if (!strcmp(this_char,"nr_blocks")) { sbinfo->max_blocks = memparse(value, &rest); if (*rest) goto bad_val; } else if (!strcmp(this_char,"nr_inodes")) { sbinfo->max_inodes = memparse(value, &rest); if (*rest) goto bad_val; } else if (!strcmp(this_char,"mode")) { if (remount) continue; sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777; if (*rest) goto bad_val; } else if (!strcmp(this_char,"uid")) { if (remount) continue; sbinfo->uid = simple_strtoul(value, &rest, 0); if (*rest) goto bad_val; } else if (!strcmp(this_char,"gid")) { if (remount) continue; sbinfo->gid = simple_strtoul(value, &rest, 0); if (*rest) goto bad_val; } else if (!strcmp(this_char,"mpol")) { if (mpol_parse_str(value, &sbinfo->mpol, 1)) 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); struct shmem_sb_info config = *sbinfo; unsigned long inodes; int error = -EINVAL; if (shmem_parse_options(data, &config, true)) return error; spin_lock(&sbinfo->stat_lock); inodes = sbinfo->max_inodes - sbinfo->free_inodes; if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0) goto out; if (config.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 (config.max_blocks && !sbinfo->max_blocks) goto out; if (config.max_inodes && !sbinfo->max_inodes) goto out; error = 0; sbinfo->max_blocks = config.max_blocks; sbinfo->max_inodes = config.max_inodes; sbinfo->free_inodes = config.max_inodes - inodes; mpol_put(sbinfo->mpol); sbinfo->mpol = config.mpol; /* transfers initial ref */ out: spin_unlock(&sbinfo->stat_lock); return error; } static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs) { struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb); if (sbinfo->max_blocks != shmem_default_max_blocks()) seq_printf(seq, ",size=%luk", sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10)); if (sbinfo->max_inodes != shmem_default_max_inodes()) seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes); if (sbinfo->mode != (S_IRWXUGO | S_ISVTX)) seq_printf(seq, ",mode=%03o", sbinfo->mode); if (sbinfo->uid != 0) seq_printf(seq, ",uid=%u", sbinfo->uid); if (sbinfo->gid != 0) seq_printf(seq, ",gid=%u", sbinfo->gid); shmem_show_mpol(seq, sbinfo->mpol); return 0; } #endif /* CONFIG_TMPFS */ static void shmem_put_super(struct super_block *sb) { struct shmem_sb_info *sbinfo = SHMEM_SB(sb); percpu_counter_destroy(&sbinfo->used_blocks); kfree(sbinfo); sb->s_fs_info = NULL; } int shmem_fill_super(struct super_block *sb, void *data, int silent) { struct inode *inode; struct dentry *root; struct shmem_sb_info *sbinfo; int err = -ENOMEM; /* Round up to L1_CACHE_BYTES to resist false sharing */ sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info), L1_CACHE_BYTES), GFP_KERNEL); if (!sbinfo) return -ENOMEM; sbinfo->mode = S_IRWXUGO | S_ISVTX; sbinfo->uid = current_fsuid(); sbinfo->gid = current_fsgid(); sb->s_fs_info = sbinfo; #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)) { sbinfo->max_blocks = shmem_default_max_blocks(); sbinfo->max_inodes = shmem_default_max_inodes(); if (shmem_parse_options(data, sbinfo, false)) { err = -EINVAL; goto failed; } } sb->s_export_op = &shmem_export_ops; #else sb->s_flags |= MS_NOUSER; #endif spin_lock_init(&sbinfo->stat_lock); if (percpu_counter_init(&sbinfo->used_blocks, 0)) goto failed; sbinfo->free_inodes = sbinfo->max_inodes; 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, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE); if (!inode) goto failed; inode->i_uid = sbinfo->uid; inode->i_gid = sbinfo->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_i_callback(struct rcu_head *head) { struct inode *inode = container_of(head, struct inode, i_rcu); INIT_LIST_HEAD(&inode->i_dentry); kmem_cache_free(shmem_inode_cachep, SHMEM_I(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); } call_rcu(&inode->i_rcu, shmem_i_callback); } static void init_once(void *foo) { struct shmem_inode_info *p = (struct shmem_inode_info *) foo; inode_init_once(&p->vfs_inode); } static int init_inodecache(void) { shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", sizeof(struct shmem_inode_info), 0, SLAB_PANIC, init_once); 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 .readpage = shmem_readpage, .write_begin = shmem_write_begin, .write_end = shmem_write_end, #endif .migratepage = migrate_page, .error_remove_page = generic_error_remove_page, }; static const struct file_operations shmem_file_operations = { .mmap = shmem_mmap, #ifdef CONFIG_TMPFS .llseek = generic_file_llseek, .read = do_sync_read, .write = do_sync_write, .aio_read = shmem_file_aio_read, .aio_write = generic_file_aio_write, .fsync = noop_fsync, .splice_read = generic_file_splice_read, .splice_write = generic_file_splice_write, #endif }; static const struct inode_operations shmem_inode_operations = { .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, .check_acl = generic_check_acl, #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, .check_acl = generic_check_acl, #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, .check_acl = generic_check_acl, #endif }; static const 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, .show_options = shmem_show_options, #endif .evict_inode = shmem_evict_inode, .drop_inode = generic_delete_inode, .put_super = shmem_put_super, }; static const struct vm_operations_struct shmem_vm_ops = { .fault = shmem_fault, #ifdef CONFIG_NUMA .set_policy = shmem_set_policy, .get_policy = shmem_get_policy, #endif }; static struct dentry *shmem_mount(struct file_system_type *fs_type, int flags, const char *dev_name, void *data) { return mount_nodev(fs_type, flags, data, shmem_fill_super); } static struct file_system_type tmpfs_fs_type = { .owner = THIS_MODULE, .name = "tmpfs", .mount = shmem_mount, .kill_sb = kill_litter_super, }; int __init init_tmpfs(void) { int error; error = bdi_init(&shmem_backing_dev_info); if (error) goto out4; 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: bdi_destroy(&shmem_backing_dev_info); out4: shm_mnt = ERR_PTR(error); return error; } #ifdef CONFIG_CGROUP_MEM_RES_CTLR /** * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file * @inode: the inode to be searched * @pgoff: the offset to be searched * @pagep: the pointer for the found page to be stored * @ent: the pointer for the found swap entry to be stored * * If a page is found, refcount of it is incremented. Callers should handle * these refcount. */ void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff, struct page **pagep, swp_entry_t *ent) { swp_entry_t entry = { .val = 0 }, *ptr; struct page *page = NULL; struct shmem_inode_info *info = SHMEM_I(inode); if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) goto out; spin_lock(&info->lock); ptr = shmem_swp_entry(info, pgoff, NULL); #ifdef CONFIG_SWAP if (ptr && ptr->val) { entry.val = ptr->val; page = find_get_page(&swapper_space, entry.val); } else #endif page = find_get_page(inode->i_mapping, pgoff); if (ptr) shmem_swp_unmap(ptr); spin_unlock(&info->lock); out: *pagep = page; *ent = entry; } #endif #else /* !CONFIG_SHMEM */ /* * tiny-shmem: simple shmemfs and tmpfs using ramfs code * * This is intended for small system where the benefits of the full * shmem code (swap-backed and resource-limited) are outweighed by * their complexity. On systems without swap this code should be * effectively equivalent, but much lighter weight. */ #include static struct file_system_type tmpfs_fs_type = { .name = "tmpfs", .mount = ramfs_mount, .kill_sb = kill_litter_super, }; int __init init_tmpfs(void) { BUG_ON(register_filesystem(&tmpfs_fs_type) != 0); shm_mnt = kern_mount(&tmpfs_fs_type); BUG_ON(IS_ERR(shm_mnt)); return 0; } int shmem_unuse(swp_entry_t entry, struct page *page) { return 0; } int shmem_lock(struct file *file, int lock, struct user_struct *user) { return 0; } #ifdef CONFIG_CGROUP_MEM_RES_CTLR /** * mem_cgroup_get_shmem_target - find a page or entry assigned to the shmem file * @inode: the inode to be searched * @pgoff: the offset to be searched * @pagep: the pointer for the found page to be stored * @ent: the pointer for the found swap entry to be stored * * If a page is found, refcount of it is incremented. Callers should handle * these refcount. */ void mem_cgroup_get_shmem_target(struct inode *inode, pgoff_t pgoff, struct page **pagep, swp_entry_t *ent) { struct page *page = NULL; if ((pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode)) goto out; page = find_get_page(inode->i_mapping, pgoff); out: *pagep = page; *ent = (swp_entry_t){ .val = 0 }; } #endif #define shmem_vm_ops generic_file_vm_ops #define shmem_file_operations ramfs_file_operations #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev) #define shmem_acct_size(flags, size) 0 #define shmem_unacct_size(flags, size) do {} while (0) #define SHMEM_MAX_BYTES MAX_LFS_FILESIZE #endif /* CONFIG_SHMEM */ /* common code */ /** * shmem_file_setup - get an unlinked file living in tmpfs * @name: name for dentry (to be seen in /proc//maps * @size: size to be set for the file * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size */ struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags) { int error; struct file *file; struct inode *inode; struct path path; struct 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; path.dentry = d_alloc(root, &this); if (!path.dentry) goto put_memory; path.mnt = mntget(shm_mnt); error = -ENOSPC; inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags); if (!inode) goto put_dentry; d_instantiate(path.dentry, inode); inode->i_size = size; inode->i_nlink = 0; /* It is unlinked */ #ifndef CONFIG_MMU error = ramfs_nommu_expand_for_mapping(inode, size); if (error) goto put_dentry; #endif error = -ENFILE; file = alloc_file(&path, FMODE_WRITE | FMODE_READ, &shmem_file_operations); if (!file) goto put_dentry; return file; put_dentry: path_put(&path); put_memory: shmem_unacct_size(flags, size); return ERR_PTR(error); } EXPORT_SYMBOL_GPL(shmem_file_setup); void shmem_set_file(struct vm_area_struct *vma, struct file *file) { if (vma->vm_file) fput(vma->vm_file); vma->vm_file = file; vma->vm_ops = &shmem_vm_ops; } /** * 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); shmem_set_file(vma, file); return 0; }