/* * 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 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 #include #include #define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) #define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) /* Pretend that each entry is of this size in directory's i_size */ #define BOGO_DIRENT_SIZE 20 struct shmem_xattr { struct list_head list; /* anchored by shmem_inode_info->xattr_list */ char *name; /* xattr name */ size_t size; char value[0]; }; /* Flag allocation requirements to shmem_getpage */ 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_gfp(struct inode *inode, pgoff_t index, struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type); static inline int shmem_getpage(struct inode *inode, pgoff_t index, struct page **pagep, enum sgp_type sgp, int *fault_type) { return shmem_getpage_gfp(inode, index, pagep, sgp, mapping_gfp_mask(inode->i_mapping), fault_type); } 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, }; static LIST_HEAD(shmem_swaplist); static DEFINE_MUTEX(shmem_swaplist_mutex); 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 block usage 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) { struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); if (sbinfo->max_blocks) percpu_counter_add(&sbinfo->used_blocks, -freed); info->alloced -= freed; inode->i_blocks -= freed * BLOCKS_PER_PAGE; shmem_unacct_blocks(info->flags, freed); } } static void shmem_put_swap(struct shmem_inode_info *info, pgoff_t index, swp_entry_t swap) { if (index < SHMEM_NR_DIRECT) info->i_direct[index] = swap; } static swp_entry_t shmem_get_swap(struct shmem_inode_info *info, pgoff_t index) { return (index < SHMEM_NR_DIRECT) ? info->i_direct[index] : (swp_entry_t){0}; } /* * Replace item expected in radix tree by a new item, while holding tree lock. */ static int shmem_radix_tree_replace(struct address_space *mapping, pgoff_t index, void *expected, void *replacement) { void **pslot; void *item = NULL; VM_BUG_ON(!expected); pslot = radix_tree_lookup_slot(&mapping->page_tree, index); if (pslot) item = radix_tree_deref_slot_protected(pslot, &mapping->tree_lock); if (item != expected) return -ENOENT; if (replacement) radix_tree_replace_slot(pslot, replacement); else radix_tree_delete(&mapping->page_tree, index); return 0; } /* * Like add_to_page_cache_locked, but error if expected item has gone. */ static int shmem_add_to_page_cache(struct page *page, struct address_space *mapping, pgoff_t index, gfp_t gfp, void *expected) { int error; VM_BUG_ON(!PageLocked(page)); VM_BUG_ON(!PageSwapBacked(page)); error = mem_cgroup_cache_charge(page, current->mm, gfp & GFP_RECLAIM_MASK); if (error) goto out; if (!expected) error = radix_tree_preload(gfp & GFP_RECLAIM_MASK); if (!error) { page_cache_get(page); page->mapping = mapping; page->index = index; spin_lock_irq(&mapping->tree_lock); if (!expected) error = radix_tree_insert(&mapping->page_tree, index, page); else error = shmem_radix_tree_replace(mapping, index, expected, page); if (!error) { mapping->nrpages++; __inc_zone_page_state(page, NR_FILE_PAGES); __inc_zone_page_state(page, NR_SHMEM); spin_unlock_irq(&mapping->tree_lock); } else { page->mapping = NULL; spin_unlock_irq(&mapping->tree_lock); page_cache_release(page); } if (!expected) radix_tree_preload_end(); } if (error) mem_cgroup_uncharge_cache_page(page); out: return error; } /* * Like find_get_pages, but collecting swap entries as well as pages. */ static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping, pgoff_t start, unsigned int nr_pages, struct page **pages, pgoff_t *indices) { unsigned int i; unsigned int ret; unsigned int nr_found; rcu_read_lock(); restart: nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, (void ***)pages, indices, start, nr_pages); ret = 0; for (i = 0; i < nr_found; i++) { struct page *page; repeat: page = radix_tree_deref_slot((void **)pages[i]); if (unlikely(!page)) continue; if (radix_tree_exception(page)) { if (radix_tree_exceptional_entry(page)) goto export; /* radix_tree_deref_retry(page) */ goto restart; } if (!page_cache_get_speculative(page)) goto repeat; /* Has the page moved? */ if (unlikely(page != *((void **)pages[i]))) { page_cache_release(page); goto repeat; } export: indices[ret] = indices[i]; pages[ret] = page; ret++; } if (unlikely(!ret && nr_found)) goto restart; rcu_read_unlock(); return ret; } /* * Lockless lookup of swap entry in radix tree, avoiding refcount on pages. */ static pgoff_t shmem_find_swap(struct address_space *mapping, void *radswap) { void **slots[PAGEVEC_SIZE]; pgoff_t indices[PAGEVEC_SIZE]; unsigned int nr_found; restart: nr_found = 1; indices[0] = -1; while (nr_found) { pgoff_t index = indices[nr_found - 1] + 1; unsigned int i; rcu_read_lock(); nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree, slots, indices, index, PAGEVEC_SIZE); for (i = 0; i < nr_found; i++) { void *item = radix_tree_deref_slot(slots[i]); if (radix_tree_deref_retry(item)) { rcu_read_unlock(); goto restart; } if (item == radswap) { rcu_read_unlock(); return indices[i]; } } rcu_read_unlock(); cond_resched(); } return -1; } /* * Remove swap entry from radix tree, free the swap and its page cache. */ static int shmem_free_swap(struct address_space *mapping, pgoff_t index, void *radswap) { int error; spin_lock_irq(&mapping->tree_lock); error = shmem_radix_tree_replace(mapping, index, radswap, NULL); spin_unlock_irq(&mapping->tree_lock); if (!error) free_swap_and_cache(radix_to_swp_entry(radswap)); return error; } /* * Pagevec may contain swap entries, so shuffle up pages before releasing. */ static void shmem_pagevec_release(struct pagevec *pvec) { int i, j; for (i = 0, j = 0; i < pagevec_count(pvec); i++) { struct page *page = pvec->pages[i]; if (!radix_tree_exceptional_entry(page)) pvec->pages[j++] = page; } pvec->nr = j; pagevec_release(pvec); } /* * Remove range of pages and swap entries from radix tree, and free them. */ void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) { struct address_space *mapping = inode->i_mapping; struct shmem_inode_info *info = SHMEM_I(inode); pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; unsigned partial = lstart & (PAGE_CACHE_SIZE - 1); pgoff_t end = (lend >> PAGE_CACHE_SHIFT); struct pagevec pvec; pgoff_t indices[PAGEVEC_SIZE]; long nr_swaps_freed = 0; pgoff_t index; int i; BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1)); pagevec_init(&pvec, 0); index = start; while (index <= end) { pvec.nr = shmem_find_get_pages_and_swap(mapping, index, min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1, pvec.pages, indices); if (!pvec.nr) break; mem_cgroup_uncharge_start(); for (i = 0; i < pagevec_count(&pvec); i++) { struct page *page = pvec.pages[i]; index = indices[i]; if (index > end) break; if (radix_tree_exceptional_entry(page)) { nr_swaps_freed += !shmem_free_swap(mapping, index, page); continue; } if (!trylock_page(page)) continue; if (page->mapping == mapping) { VM_BUG_ON(PageWriteback(page)); truncate_inode_page(mapping, page); } unlock_page(page); } shmem_pagevec_release(&pvec); mem_cgroup_uncharge_end(); cond_resched(); index++; } if (partial) { struct page *page = NULL; shmem_getpage(inode, start - 1, &page, SGP_READ, NULL); if (page) { zero_user_segment(page, partial, PAGE_CACHE_SIZE); set_page_dirty(page); unlock_page(page); page_cache_release(page); } } index = start; for ( ; ; ) { cond_resched(); pvec.nr = shmem_find_get_pages_and_swap(mapping, index, min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1, pvec.pages, indices); if (!pvec.nr) { if (index == start) break; index = start; continue; } if (index == start && indices[0] > end) { shmem_pagevec_release(&pvec); break; } mem_cgroup_uncharge_start(); for (i = 0; i < pagevec_count(&pvec); i++) { struct page *page = pvec.pages[i]; index = indices[i]; if (index > end) break; if (radix_tree_exceptional_entry(page)) { nr_swaps_freed += !shmem_free_swap(mapping, index, page); continue; } lock_page(page); if (page->mapping == mapping) { VM_BUG_ON(PageWriteback(page)); truncate_inode_page(mapping, page); } unlock_page(page); } shmem_pagevec_release(&pvec); mem_cgroup_uncharge_end(); index++; } spin_lock(&info->lock); info->swapped -= nr_swaps_freed; shmem_recalc_inode(inode); spin_unlock(&info->lock); inode->i_ctime = inode->i_mtime = CURRENT_TIME; } EXPORT_SYMBOL_GPL(shmem_truncate_range); static int shmem_setattr(struct dentry *dentry, struct iattr *attr) { struct inode *inode = dentry->d_inode; int error; error = inode_change_ok(inode, attr); if (error) return error; if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { loff_t oldsize = inode->i_size; loff_t newsize = attr->ia_size; if (newsize != oldsize) { i_size_write(inode, newsize); inode->i_ctime = inode->i_mtime = CURRENT_TIME; } if (newsize < oldsize) { loff_t holebegin = round_up(newsize, PAGE_SIZE); unmap_mapping_range(inode->i_mapping, holebegin, 0, 1); shmem_truncate_range(inode, newsize, (loff_t)-1); /* unmap again to remove racily COWed private pages */ unmap_mapping_range(inode->i_mapping, holebegin, 0, 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); struct shmem_xattr *xattr, *nxattr; if (inode->i_mapping->a_ops == &shmem_aops) { 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); } } list_for_each_entry_safe(xattr, nxattr, &info->xattr_list, list) { kfree(xattr->name); kfree(xattr); } BUG_ON(inode->i_blocks); shmem_free_inode(inode->i_sb); end_writeback(inode); } /* * If swap found in inode, free it and move page from swapcache to filecache. */ static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t swap, struct page *page) { struct address_space *mapping = info->vfs_inode.i_mapping; void *radswap; pgoff_t index; int error; radswap = swp_to_radix_entry(swap); index = shmem_find_swap(mapping, radswap); if (index == -1) return 0; /* * 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. */ if (shmem_swaplist.next != &info->swaplist) list_move_tail(&shmem_swaplist, &info->swaplist); /* * We rely on shmem_swaplist_mutex, not only to protect the swaplist, * but also to hold up shmem_evict_inode(): so inode cannot be freed * beneath us (pagelock doesn't help until the page is in pagecache). */ error = shmem_add_to_page_cache(page, mapping, index, GFP_NOWAIT, radswap); /* which does mem_cgroup_uncharge_cache_page on error */ if (error != -ENOMEM) { /* * Truncation and eviction use free_swap_and_cache(), which * only does trylock page: if we raced, best clean up here. */ delete_from_swap_cache(page); set_page_dirty(page); if (!error) { spin_lock(&info->lock); info->swapped--; spin_unlock(&info->lock); swap_free(swap); } error = 1; /* not an error, but entry was found */ } return error; } /* * Search through swapped inodes to find and replace swap by page. */ int shmem_unuse(swp_entry_t swap, struct page *page) { struct list_head *this, *next; struct shmem_inode_info *info; int found = 0; int error; /* * Charge page using GFP_KERNEL while we can wait, before taking * the shmem_swaplist_mutex which might hold up shmem_writepage(). * Charged back to the user (not to caller) when swap account is used. * shmem_add_to_page_cache() will be called with GFP_NOWAIT. */ error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL); if (error) goto out; /* No radix_tree_preload: swap entry keeps a place for page in tree */ mutex_lock(&shmem_swaplist_mutex); list_for_each_safe(this, next, &shmem_swaplist) { info = list_entry(this, struct shmem_inode_info, swaplist); if (!info->swapped) { spin_lock(&info->lock); if (!info->swapped) list_del_init(&info->swaplist); spin_unlock(&info->lock); } if (info->swapped) found = shmem_unuse_inode(info, swap, page); cond_resched(); if (found) break; } mutex_unlock(&shmem_swaplist_mutex); if (!found) mem_cgroup_uncharge_cache_page(page); if (found < 0) error = found; out: unlock_page(page); page_cache_release(page); return error; } /* * 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 swap, oswap; struct address_space *mapping; pgoff_t 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 * might use ->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. */ if (!wbc->for_reclaim) { WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ goto redirty; } /* * Disable even the toy swapping implementation, while we convert * functions one by one to having swap entries in the radix tree. */ if (index < ULONG_MAX) goto redirty; swap = get_swap_page(); if (!swap.val) goto redirty; /* * Add inode to shmem_unuse()'s list of swapped-out inodes, * if it's not already there. Do it now because we cannot take * mutex while holding spinlock, and must do so before the page * is moved to swap cache, when its pagelock no longer protects * the inode from eviction. But don't unlock the mutex until * we've taken the spinlock, because shmem_unuse_inode() will * prune a !swapped inode from the swaplist under both locks. */ mutex_lock(&shmem_swaplist_mutex); if (list_empty(&info->swaplist)) list_add_tail(&info->swaplist, &shmem_swaplist); spin_lock(&info->lock); mutex_unlock(&shmem_swaplist_mutex); oswap = shmem_get_swap(info, index); if (oswap.val) { WARN_ON_ONCE(1); /* Still happens? Tell us about it! */ free_swap_and_cache(oswap); shmem_put_swap(info, index, (swp_entry_t){0}); info->swapped--; } shmem_recalc_inode(inode); if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) { delete_from_page_cache(page); shmem_put_swap(info, index, swap); info->swapped++; swap_shmem_alloc(swap); spin_unlock(&info->lock); BUG_ON(page_mapped(page)); swap_writepage(page, wbc); return 0; } spin_unlock(&info->lock); 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 swap, gfp_t gfp, struct shmem_inode_info *info, pgoff_t index) { struct mempolicy mpol, *spol; struct vm_area_struct pvma; spol = mpol_cond_copy(&mpol, mpol_shared_policy_lookup(&info->policy, index)); /* Create a pseudo vma that just contains the policy */ pvma.vm_start = 0; pvma.vm_pgoff = index; pvma.vm_ops = NULL; pvma.vm_policy = spol; return swapin_readahead(swap, gfp, &pvma, 0); } static struct page *shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info, pgoff_t index) { struct vm_area_struct pvma; /* Create a pseudo vma that just contains the policy */ pvma.vm_start = 0; pvma.vm_pgoff = index; pvma.vm_ops = NULL; pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); /* * 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 *mpol) { } #endif /* CONFIG_TMPFS */ static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, struct shmem_inode_info *info, pgoff_t index) { return swapin_readahead(swap, gfp, NULL, 0); } static inline struct page *shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info, pgoff_t index) { 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_gfp - find page in cache, or get from swap, or allocate * * 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_gfp(struct inode *inode, pgoff_t index, struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type) { struct address_space *mapping = inode->i_mapping; struct shmem_inode_info *info; struct shmem_sb_info *sbinfo; struct page *page; swp_entry_t swap; int error; int once = 0; if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT)) return -EFBIG; repeat: swap.val = 0; page = find_lock_page(mapping, index); if (radix_tree_exceptional_entry(page)) { swap = radix_to_swp_entry(page); page = NULL; } if (sgp != SGP_WRITE && ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { error = -EINVAL; goto failed; } if (page || (sgp == SGP_READ && !swap.val)) { /* * Once we can get the page lock, it must be uptodate: * if there were an error in reading back from swap, * the page would not be inserted into the filecache. */ BUG_ON(page && !PageUptodate(page)); *pagep = page; return 0; } /* * Fast cache lookup did not find it: * bring it back from swap or allocate. */ info = SHMEM_I(inode); sbinfo = SHMEM_SB(inode->i_sb); if (swap.val) { /* Look it up and read it in.. */ page = lookup_swap_cache(swap); if (!page) { /* here we actually do the io */ if (fault_type) *fault_type |= VM_FAULT_MAJOR; page = shmem_swapin(swap, gfp, info, index); if (!page) { error = -ENOMEM; goto failed; } } /* We have to do this with page locked to prevent races */ lock_page(page); if (!PageUptodate(page)) { error = -EIO; goto failed; } wait_on_page_writeback(page); /* Someone may have already done it for us */ if (page->mapping) { if (page->mapping == mapping && page->index == index) goto done; error = -EEXIST; goto failed; } error = shmem_add_to_page_cache(page, mapping, index, gfp, swp_to_radix_entry(swap)); if (error) goto failed; spin_lock(&info->lock); info->swapped--; shmem_recalc_inode(inode); spin_unlock(&info->lock); delete_from_swap_cache(page); set_page_dirty(page); swap_free(swap); } else { if (shmem_acct_block(info->flags)) { error = -ENOSPC; goto failed; } if (sbinfo->max_blocks) { if (percpu_counter_compare(&sbinfo->used_blocks, sbinfo->max_blocks) >= 0) { error = -ENOSPC; goto unacct; } percpu_counter_inc(&sbinfo->used_blocks); } page = shmem_alloc_page(gfp, info, index); if (!page) { error = -ENOMEM; goto decused; } SetPageSwapBacked(page); __set_page_locked(page); error = shmem_add_to_page_cache(page, mapping, index, gfp, NULL); if (error) goto decused; lru_cache_add_anon(page); spin_lock(&info->lock); info->alloced++; inode->i_blocks += BLOCKS_PER_PAGE; shmem_recalc_inode(inode); spin_unlock(&info->lock); clear_highpage(page); flush_dcache_page(page); SetPageUptodate(page); if (sgp == SGP_DIRTY) set_page_dirty(page); } done: /* Perhaps the file has been truncated since we checked */ if (sgp != SGP_WRITE && ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { error = -EINVAL; goto trunc; } *pagep = page; return 0; /* * Error recovery. */ trunc: ClearPageDirty(page); delete_from_page_cache(page); spin_lock(&info->lock); info->alloced--; inode->i_blocks -= BLOCKS_PER_PAGE; spin_unlock(&info->lock); decused: if (sbinfo->max_blocks) percpu_counter_add(&sbinfo->used_blocks, -1); unacct: shmem_unacct_blocks(info->flags, 1); failed: if (swap.val && error != -EINVAL) { struct page *test = find_get_page(mapping, index); if (test && !radix_tree_exceptional_entry(test)) page_cache_release(test); /* Have another try if the entry has changed */ if (test != swp_to_radix_entry(swap)) error = -EEXIST; } if (page) { unlock_page(page); page_cache_release(page); } if (error == -ENOSPC && !once++) { info = SHMEM_I(inode); spin_lock(&info->lock); shmem_recalc_inode(inode); spin_unlock(&info->lock); goto repeat; } if (error == -EEXIST) goto repeat; 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 = VM_FAULT_LOCKED; error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret); if (error) return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS); if (ret & VM_FAULT_MAJOR) { count_vm_event(PGMAJFAULT); mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT); } return ret; } #ifdef CONFIG_NUMA static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol) { struct inode *inode = vma->vm_file->f_path.dentry->d_inode; return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol); } static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma, unsigned long addr) { struct inode *inode = vma->vm_file->f_path.dentry->d_inode; pgoff_t index; index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index); } #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); INIT_LIST_HEAD(&info->xattr_list); 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; 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; 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; pgoff_t index; unsigned long 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; pgoff_t end_index; unsigned long 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 ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos, struct pipe_inode_info *pipe, size_t len, unsigned int flags) { struct address_space *mapping = in->f_mapping; struct inode *inode = mapping->host; unsigned int loff, nr_pages, req_pages; struct page *pages[PIPE_DEF_BUFFERS]; struct partial_page partial[PIPE_DEF_BUFFERS]; struct page *page; pgoff_t index, end_index; loff_t isize, left; int error, page_nr; struct splice_pipe_desc spd = { .pages = pages, .partial = partial, .flags = flags, .ops = &page_cache_pipe_buf_ops, .spd_release = spd_release_page, }; isize = i_size_read(inode); if (unlikely(*ppos >= isize)) return 0; left = isize - *ppos; if (unlikely(left < len)) len = left; if (splice_grow_spd(pipe, &spd)) return -ENOMEM; index = *ppos >> PAGE_CACHE_SHIFT; loff = *ppos & ~PAGE_CACHE_MASK; req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; nr_pages = min(req_pages, pipe->buffers); spd.nr_pages = find_get_pages_contig(mapping, index, nr_pages, spd.pages); index += spd.nr_pages; error = 0; while (spd.nr_pages < nr_pages) { error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL); if (error) break; unlock_page(page); spd.pages[spd.nr_pages++] = page; index++; } index = *ppos >> PAGE_CACHE_SHIFT; nr_pages = spd.nr_pages; spd.nr_pages = 0; for (page_nr = 0; page_nr < nr_pages; page_nr++) { unsigned int this_len; if (!len) break; this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff); page = spd.pages[page_nr]; if (!PageUptodate(page) || page->mapping != mapping) { error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL); if (error) break; unlock_page(page); page_cache_release(spd.pages[page_nr]); spd.pages[page_nr] = page; } isize = i_size_read(inode); end_index = (isize - 1) >> PAGE_CACHE_SHIFT; if (unlikely(!isize || index > end_index)) break; if (end_index == index) { unsigned int plen; plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1; if (plen <= loff) break; this_len = min(this_len, plen - loff); len = this_len; } spd.partial[page_nr].offset = loff; spd.partial[page_nr].len = this_len; len -= this_len; loff = 0; spd.nr_pages++; index++; } while (page_nr < nr_pages) page_cache_release(spd.pages[page_nr++]); if (spd.nr_pages) error = splice_to_pipe(pipe, &spd); splice_shrink_spd(pipe, &spd); if (error > 0) { *ppos += error; file_accessed(in); } return 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; 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, &dentry->d_name, 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; 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, &dentry->d_name, 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 <= SHMEM_SYMLINK_INLINE_LEN) { /* do it inline */ memcpy(info->inline_symlink, 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, SHMEM_I(dentry->d_inode)->inline_symlink); return NULL; } static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) { struct page *page = NULL; int error = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); nd_set_link(nd, error ? ERR_PTR(error) : 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); } } #ifdef CONFIG_TMPFS_XATTR /* * Superblocks without xattr inode operations may get some security.* xattr * support from the LSM "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 int shmem_xattr_get(struct dentry *dentry, const char *name, void *buffer, size_t size) { struct shmem_inode_info *info; struct shmem_xattr *xattr; int ret = -ENODATA; info = SHMEM_I(dentry->d_inode); spin_lock(&info->lock); list_for_each_entry(xattr, &info->xattr_list, list) { if (strcmp(name, xattr->name)) continue; ret = xattr->size; if (buffer) { if (size < xattr->size) ret = -ERANGE; else memcpy(buffer, xattr->value, xattr->size); } break; } spin_unlock(&info->lock); return ret; } static int shmem_xattr_set(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) { struct inode *inode = dentry->d_inode; struct shmem_inode_info *info = SHMEM_I(inode); struct shmem_xattr *xattr; struct shmem_xattr *new_xattr = NULL; size_t len; int err = 0; /* value == NULL means remove */ if (value) { /* wrap around? */ len = sizeof(*new_xattr) + size; if (len <= sizeof(*new_xattr)) return -ENOMEM; new_xattr = kmalloc(len, GFP_KERNEL); if (!new_xattr) return -ENOMEM; new_xattr->name = kstrdup(name, GFP_KERNEL); if (!new_xattr->name) { kfree(new_xattr); return -ENOMEM; } new_xattr->size = size; memcpy(new_xattr->value, value, size); } spin_lock(&info->lock); list_for_each_entry(xattr, &info->xattr_list, list) { if (!strcmp(name, xattr->name)) { if (flags & XATTR_CREATE) { xattr = new_xattr; err = -EEXIST; } else if (new_xattr) { list_replace(&xattr->list, &new_xattr->list); } else { list_del(&xattr->list); } goto out; } } if (flags & XATTR_REPLACE) { xattr = new_xattr; err = -ENODATA; } else { list_add(&new_xattr->list, &info->xattr_list); xattr = NULL; } out: spin_unlock(&info->lock); if (xattr) kfree(xattr->name); kfree(xattr); return err; } static const struct xattr_handler *shmem_xattr_handlers[] = { #ifdef CONFIG_TMPFS_POSIX_ACL &generic_acl_access_handler, &generic_acl_default_handler, #endif NULL }; static int shmem_xattr_validate(const char *name) { struct { const char *prefix; size_t len; } arr[] = { { XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN }, { XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN } }; int i; for (i = 0; i < ARRAY_SIZE(arr); i++) { size_t preflen = arr[i].len; if (strncmp(name, arr[i].prefix, preflen) == 0) { if (!name[preflen]) return -EINVAL; return 0; } } return -EOPNOTSUPP; } static ssize_t shmem_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size) { int err; /* * If this is a request for a synthetic attribute in the system.* * namespace use the generic infrastructure to resolve a handler * for it via sb->s_xattr. */ if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) return generic_getxattr(dentry, name, buffer, size); err = shmem_xattr_validate(name); if (err) return err; return shmem_xattr_get(dentry, name, buffer, size); } static int shmem_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) { int err; /* * If this is a request for a synthetic attribute in the system.* * namespace use the generic infrastructure to resolve a handler * for it via sb->s_xattr. */ if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) return generic_setxattr(dentry, name, value, size, flags); err = shmem_xattr_validate(name); if (err) return err; if (size == 0) value = ""; /* empty EA, do not remove */ return shmem_xattr_set(dentry, name, value, size, flags); } static int shmem_removexattr(struct dentry *dentry, const char *name) { int err; /* * If this is a request for a synthetic attribute in the system.* * namespace use the generic infrastructure to resolve a handler * for it via sb->s_xattr. */ if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) return generic_removexattr(dentry, name); err = shmem_xattr_validate(name); if (err) return err; return shmem_xattr_set(dentry, name, NULL, 0, XATTR_REPLACE); } static bool xattr_is_trusted(const char *name) { return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN); } static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size) { bool trusted = capable(CAP_SYS_ADMIN); struct shmem_xattr *xattr; struct shmem_inode_info *info; size_t used = 0; info = SHMEM_I(dentry->d_inode); spin_lock(&info->lock); list_for_each_entry(xattr, &info->xattr_list, list) { size_t len; /* skip "trusted." attributes for unprivileged callers */ if (!trusted && xattr_is_trusted(xattr->name)) continue; len = strlen(xattr->name) + 1; used += len; if (buffer) { if (size < used) { used = -ERANGE; break; } memcpy(buffer, xattr->name, len); buffer += len; } } spin_unlock(&info->lock); return used; } #endif /* CONFIG_TMPFS_XATTR */ static const struct inode_operations shmem_symlink_inline_operations = { .readlink = generic_readlink, .follow_link = shmem_follow_link_inline, #ifdef CONFIG_TMPFS_XATTR .setxattr = shmem_setxattr, .getxattr = shmem_getxattr, .listxattr = shmem_listxattr, .removexattr = shmem_removexattr, #endif }; 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_XATTR .setxattr = shmem_setxattr, .getxattr = shmem_getxattr, .listxattr = shmem_listxattr, .removexattr = shmem_removexattr, #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) { *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 disallow limited->unlimited while any are in use; * 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 = MAX_LFS_FILESIZE; 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_XATTR sb->s_xattr = shmem_xattr_handlers; #endif #ifdef CONFIG_TMPFS_POSIX_ACL 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 *info; info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); if (!info) return NULL; return &info->vfs_inode; } static void shmem_destroy_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_destroy_callback); } static void shmem_init_inode(void *foo) { struct shmem_inode_info *info = foo; inode_init_once(&info->vfs_inode); } static int shmem_init_inodecache(void) { shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", sizeof(struct shmem_inode_info), 0, SLAB_PANIC, shmem_init_inode); return 0; } static void shmem_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 .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 = shmem_file_splice_read, .splice_write = generic_file_splice_write, #endif }; static const struct inode_operations shmem_inode_operations = { .setattr = shmem_setattr, .truncate_range = shmem_truncate_range, #ifdef CONFIG_TMPFS_XATTR .setxattr = shmem_setxattr, .getxattr = shmem_getxattr, .listxattr = shmem_listxattr, .removexattr = shmem_removexattr, #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_XATTR .setxattr = shmem_setxattr, .getxattr = shmem_getxattr, .listxattr = shmem_listxattr, .removexattr = shmem_removexattr, #endif #ifdef CONFIG_TMPFS_POSIX_ACL .setattr = shmem_setattr, #endif }; static const struct inode_operations shmem_special_inode_operations = { #ifdef CONFIG_TMPFS_XATTR .setxattr = shmem_setxattr, .getxattr = shmem_getxattr, .listxattr = shmem_listxattr, .removexattr = shmem_removexattr, #endif #ifdef CONFIG_TMPFS_POSIX_ACL .setattr = shmem_setattr, #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 shmem_fs_type = { .owner = THIS_MODULE, .name = "tmpfs", .mount = shmem_mount, .kill_sb = kill_litter_super, }; int __init shmem_init(void) { int error; error = bdi_init(&shmem_backing_dev_info); if (error) goto out4; error = shmem_init_inodecache(); if (error) goto out3; error = register_filesystem(&shmem_fs_type); if (error) { printk(KERN_ERR "Could not register tmpfs\n"); goto out2; } shm_mnt = vfs_kern_mount(&shmem_fs_type, MS_NOUSER, shmem_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(&shmem_fs_type); out2: shmem_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 page or swap assigned to the shmem file * @inode: the inode to be searched * @index: the page offset to be searched * @pagep: the pointer for the found page to be stored * @swapp: 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 index, struct page **pagep, swp_entry_t *swapp) { struct shmem_inode_info *info = SHMEM_I(inode); struct page *page = NULL; swp_entry_t swap = {0}; if ((index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) goto out; spin_lock(&info->lock); #ifdef CONFIG_SWAP swap = shmem_get_swap(info, index); if (swap.val) page = find_get_page(&swapper_space, swap.val); else #endif page = find_get_page(inode->i_mapping, index); spin_unlock(&info->lock); out: *pagep = page; *swapp = swap; } #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 shmem_fs_type = { .name = "tmpfs", .mount = ramfs_mount, .kill_sb = kill_litter_super, }; int __init shmem_init(void) { BUG_ON(register_filesystem(&shmem_fs_type) != 0); shm_mnt = kern_mount(&shmem_fs_type); BUG_ON(IS_ERR(shm_mnt)); return 0; } int shmem_unuse(swp_entry_t swap, struct page *page) { return 0; } int shmem_lock(struct file *file, int lock, struct user_struct *user) { return 0; } void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend) { truncate_inode_pages_range(inode->i_mapping, lstart, lend); } EXPORT_SYMBOL_GPL(shmem_truncate_range); #ifdef CONFIG_CGROUP_MEM_RES_CTLR /** * mem_cgroup_get_shmem_target - find page or swap assigned to the shmem file * @inode: the inode to be searched * @index: the page offset to be searched * @pagep: the pointer for the found page to be stored * @swapp: 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 index, struct page **pagep, swp_entry_t *swapp) { struct page *page = NULL; if ((index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) goto out; page = find_get_page(inode->i_mapping, index); out: *pagep = page; *swapp = (swp_entry_t){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) #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 > MAX_LFS_FILESIZE) 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); /** * 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; vma->vm_flags |= VM_CAN_NONLINEAR; return 0; } /** * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags. * @mapping: the page's address_space * @index: the page index * @gfp: the page allocator flags to use if allocating * * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)", * with any new page allocations done using the specified allocation flags. * But read_cache_page_gfp() uses the ->readpage() method: which does not * suit tmpfs, since it may have pages in swapcache, and needs to find those * for itself; although drivers/gpu/drm i915 and ttm rely upon this support. * * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily. */ struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, pgoff_t index, gfp_t gfp) { #ifdef CONFIG_SHMEM struct inode *inode = mapping->host; struct page *page; int error; BUG_ON(mapping->a_ops != &shmem_aops); error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL); if (error) page = ERR_PTR(error); else unlock_page(page); return page; #else /* * The tiny !SHMEM case uses ramfs without swap */ return read_cache_page_gfp(mapping, index, gfp); #endif } EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);