diff options
Diffstat (limited to 'fs/inode.c')
| -rw-r--r-- | fs/inode.c | 2454 |
1 files changed, 2454 insertions, 0 deletions
diff --git a/fs/inode.c b/fs/inode.c new file mode 100644 index 000000000..5c7139aa2 --- /dev/null +++ b/fs/inode.c @@ -0,0 +1,2454 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * (C) 1997 Linus Torvalds + * (C) 1999 Andrea Arcangeli <andrea@suse.de> (dynamic inode allocation) + */ +#include <linux/export.h> +#include <linux/fs.h> +#include <linux/mm.h> +#include <linux/backing-dev.h> +#include <linux/hash.h> +#include <linux/swap.h> +#include <linux/security.h> +#include <linux/cdev.h> +#include <linux/memblock.h> +#include <linux/fscrypt.h> +#include <linux/fsnotify.h> +#include <linux/mount.h> +#include <linux/posix_acl.h> +#include <linux/prefetch.h> +#include <linux/buffer_head.h> /* for inode_has_buffers */ +#include <linux/ratelimit.h> +#include <linux/list_lru.h> +#include <linux/iversion.h> +#include <trace/events/writeback.h> +#include "internal.h" + +/* + * Inode locking rules: + * + * inode->i_lock protects: + * inode->i_state, inode->i_hash, __iget() + * Inode LRU list locks protect: + * inode->i_sb->s_inode_lru, inode->i_lru + * inode->i_sb->s_inode_list_lock protects: + * inode->i_sb->s_inodes, inode->i_sb_list + * bdi->wb.list_lock protects: + * bdi->wb.b_{dirty,io,more_io,dirty_time}, inode->i_io_list + * inode_hash_lock protects: + * inode_hashtable, inode->i_hash + * + * Lock ordering: + * + * inode->i_sb->s_inode_list_lock + * inode->i_lock + * Inode LRU list locks + * + * bdi->wb.list_lock + * inode->i_lock + * + * inode_hash_lock + * inode->i_sb->s_inode_list_lock + * inode->i_lock + * + * iunique_lock + * inode_hash_lock + */ + +static unsigned int i_hash_mask __read_mostly; +static unsigned int i_hash_shift __read_mostly; +static struct hlist_head *inode_hashtable __read_mostly; +static __cacheline_aligned_in_smp DEFINE_SPINLOCK(inode_hash_lock); + +/* + * Empty aops. Can be used for the cases where the user does not + * define any of the address_space operations. + */ +const struct address_space_operations empty_aops = { +}; +EXPORT_SYMBOL(empty_aops); + +/* + * Statistics gathering.. + */ +struct inodes_stat_t inodes_stat; + +static DEFINE_PER_CPU(unsigned long, nr_inodes); +static DEFINE_PER_CPU(unsigned long, nr_unused); + +static struct kmem_cache *inode_cachep __read_mostly; + +static long get_nr_inodes(void) +{ + int i; + long sum = 0; + for_each_possible_cpu(i) + sum += per_cpu(nr_inodes, i); + return sum < 0 ? 0 : sum; +} + +static inline long get_nr_inodes_unused(void) +{ + int i; + long sum = 0; + for_each_possible_cpu(i) + sum += per_cpu(nr_unused, i); + return sum < 0 ? 0 : sum; +} + +long get_nr_dirty_inodes(void) +{ + /* not actually dirty inodes, but a wild approximation */ + long nr_dirty = get_nr_inodes() - get_nr_inodes_unused(); + return nr_dirty > 0 ? nr_dirty : 0; +} + +/* + * Handle nr_inode sysctl + */ +#ifdef CONFIG_SYSCTL +int proc_nr_inodes(struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) +{ + inodes_stat.nr_inodes = get_nr_inodes(); + inodes_stat.nr_unused = get_nr_inodes_unused(); + return proc_doulongvec_minmax(table, write, buffer, lenp, ppos); +} +#endif + +static int no_open(struct inode *inode, struct file *file) +{ + return -ENXIO; +} + +/** + * inode_init_always - perform inode structure initialisation + * @sb: superblock inode belongs to + * @inode: inode to initialise + * + * These are initializations that need to be done on every inode + * allocation as the fields are not initialised by slab allocation. + */ +int inode_init_always(struct super_block *sb, struct inode *inode) +{ + static const struct inode_operations empty_iops; + static const struct file_operations no_open_fops = {.open = no_open}; + struct address_space *const mapping = &inode->i_data; + + inode->i_sb = sb; + inode->i_blkbits = sb->s_blocksize_bits; + inode->i_flags = 0; + atomic64_set(&inode->i_sequence, 0); + atomic_set(&inode->i_count, 1); + inode->i_op = &empty_iops; + inode->i_fop = &no_open_fops; + inode->__i_nlink = 1; + inode->i_opflags = 0; + if (sb->s_xattr) + inode->i_opflags |= IOP_XATTR; + i_uid_write(inode, 0); + i_gid_write(inode, 0); + atomic_set(&inode->i_writecount, 0); + inode->i_size = 0; + inode->i_write_hint = WRITE_LIFE_NOT_SET; + inode->i_blocks = 0; + inode->i_bytes = 0; + inode->i_generation = 0; + inode->i_pipe = NULL; + inode->i_bdev = NULL; + inode->i_cdev = NULL; + inode->i_link = NULL; + inode->i_dir_seq = 0; + inode->i_rdev = 0; + inode->dirtied_when = 0; + +#ifdef CONFIG_CGROUP_WRITEBACK + inode->i_wb_frn_winner = 0; + inode->i_wb_frn_avg_time = 0; + inode->i_wb_frn_history = 0; +#endif + + spin_lock_init(&inode->i_lock); + lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key); + + init_rwsem(&inode->i_rwsem); + lockdep_set_class(&inode->i_rwsem, &sb->s_type->i_mutex_key); + + atomic_set(&inode->i_dio_count, 0); + + mapping->a_ops = &empty_aops; + mapping->host = inode; + mapping->flags = 0; + if (sb->s_type->fs_flags & FS_THP_SUPPORT) + __set_bit(AS_THP_SUPPORT, &mapping->flags); + mapping->wb_err = 0; + atomic_set(&mapping->i_mmap_writable, 0); +#ifdef CONFIG_READ_ONLY_THP_FOR_FS + atomic_set(&mapping->nr_thps, 0); +#endif + mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE); + mapping->private_data = NULL; + mapping->writeback_index = 0; + inode->i_private = NULL; + inode->i_mapping = mapping; + INIT_HLIST_HEAD(&inode->i_dentry); /* buggered by rcu freeing */ +#ifdef CONFIG_FS_POSIX_ACL + inode->i_acl = inode->i_default_acl = ACL_NOT_CACHED; +#endif + +#ifdef CONFIG_FSNOTIFY + inode->i_fsnotify_mask = 0; +#endif + inode->i_flctx = NULL; + + if (unlikely(security_inode_alloc(inode))) + return -ENOMEM; + this_cpu_inc(nr_inodes); + + return 0; +} +EXPORT_SYMBOL(inode_init_always); + +void free_inode_nonrcu(struct inode *inode) +{ + kmem_cache_free(inode_cachep, inode); +} +EXPORT_SYMBOL(free_inode_nonrcu); + +static void i_callback(struct rcu_head *head) +{ + struct inode *inode = container_of(head, struct inode, i_rcu); + if (inode->free_inode) + inode->free_inode(inode); + else + free_inode_nonrcu(inode); +} + +static struct inode *alloc_inode(struct super_block *sb) +{ + const struct super_operations *ops = sb->s_op; + struct inode *inode; + + if (ops->alloc_inode) + inode = ops->alloc_inode(sb); + else + inode = kmem_cache_alloc(inode_cachep, GFP_KERNEL); + + if (!inode) + return NULL; + + if (unlikely(inode_init_always(sb, inode))) { + if (ops->destroy_inode) { + ops->destroy_inode(inode); + if (!ops->free_inode) + return NULL; + } + inode->free_inode = ops->free_inode; + i_callback(&inode->i_rcu); + return NULL; + } + + return inode; +} + +void __destroy_inode(struct inode *inode) +{ + BUG_ON(inode_has_buffers(inode)); + inode_detach_wb(inode); + security_inode_free(inode); + fsnotify_inode_delete(inode); + locks_free_lock_context(inode); + if (!inode->i_nlink) { + WARN_ON(atomic_long_read(&inode->i_sb->s_remove_count) == 0); + atomic_long_dec(&inode->i_sb->s_remove_count); + } + +#ifdef CONFIG_FS_POSIX_ACL + if (inode->i_acl && !is_uncached_acl(inode->i_acl)) + posix_acl_release(inode->i_acl); + if (inode->i_default_acl && !is_uncached_acl(inode->i_default_acl)) + posix_acl_release(inode->i_default_acl); +#endif + this_cpu_dec(nr_inodes); +} +EXPORT_SYMBOL(__destroy_inode); + +static void destroy_inode(struct inode *inode) +{ + const struct super_operations *ops = inode->i_sb->s_op; + + BUG_ON(!list_empty(&inode->i_lru)); + __destroy_inode(inode); + if (ops->destroy_inode) { + ops->destroy_inode(inode); + if (!ops->free_inode) + return; + } + inode->free_inode = ops->free_inode; + call_rcu(&inode->i_rcu, i_callback); +} + +/** + * drop_nlink - directly drop an inode's link count + * @inode: inode + * + * This is a low-level filesystem helper to replace any + * direct filesystem manipulation of i_nlink. In cases + * where we are attempting to track writes to the + * filesystem, a decrement to zero means an imminent + * write when the file is truncated and actually unlinked + * on the filesystem. + */ +void drop_nlink(struct inode *inode) +{ + WARN_ON(inode->i_nlink == 0); + inode->__i_nlink--; + if (!inode->i_nlink) + atomic_long_inc(&inode->i_sb->s_remove_count); +} +EXPORT_SYMBOL(drop_nlink); + +/** + * clear_nlink - directly zero an inode's link count + * @inode: inode + * + * This is a low-level filesystem helper to replace any + * direct filesystem manipulation of i_nlink. See + * drop_nlink() for why we care about i_nlink hitting zero. + */ +void clear_nlink(struct inode *inode) +{ + if (inode->i_nlink) { + inode->__i_nlink = 0; + atomic_long_inc(&inode->i_sb->s_remove_count); + } +} +EXPORT_SYMBOL(clear_nlink); + +/** + * set_nlink - directly set an inode's link count + * @inode: inode + * @nlink: new nlink (should be non-zero) + * + * This is a low-level filesystem helper to replace any + * direct filesystem manipulation of i_nlink. + */ +void set_nlink(struct inode *inode, unsigned int nlink) +{ + if (!nlink) { + clear_nlink(inode); + } else { + /* Yes, some filesystems do change nlink from zero to one */ + if (inode->i_nlink == 0) + atomic_long_dec(&inode->i_sb->s_remove_count); + + inode->__i_nlink = nlink; + } +} +EXPORT_SYMBOL(set_nlink); + +/** + * inc_nlink - directly increment an inode's link count + * @inode: inode + * + * This is a low-level filesystem helper to replace any + * direct filesystem manipulation of i_nlink. Currently, + * it is only here for parity with dec_nlink(). + */ +void inc_nlink(struct inode *inode) +{ + if (unlikely(inode->i_nlink == 0)) { + WARN_ON(!(inode->i_state & I_LINKABLE)); + atomic_long_dec(&inode->i_sb->s_remove_count); + } + + inode->__i_nlink++; +} +EXPORT_SYMBOL(inc_nlink); + +static void __address_space_init_once(struct address_space *mapping) +{ + xa_init_flags(&mapping->i_pages, XA_FLAGS_LOCK_IRQ | XA_FLAGS_ACCOUNT); + init_rwsem(&mapping->i_mmap_rwsem); + INIT_LIST_HEAD(&mapping->private_list); + spin_lock_init(&mapping->private_lock); + mapping->i_mmap = RB_ROOT_CACHED; +} + +void address_space_init_once(struct address_space *mapping) +{ + memset(mapping, 0, sizeof(*mapping)); + __address_space_init_once(mapping); +} +EXPORT_SYMBOL(address_space_init_once); + +/* + * These are initializations that only need to be done + * once, because the fields are idempotent across use + * of the inode, so let the slab aware of that. + */ +void inode_init_once(struct inode *inode) +{ + memset(inode, 0, sizeof(*inode)); + INIT_HLIST_NODE(&inode->i_hash); + INIT_LIST_HEAD(&inode->i_devices); + INIT_LIST_HEAD(&inode->i_io_list); + INIT_LIST_HEAD(&inode->i_wb_list); + INIT_LIST_HEAD(&inode->i_lru); + __address_space_init_once(&inode->i_data); + i_size_ordered_init(inode); +} +EXPORT_SYMBOL(inode_init_once); + +static void init_once(void *foo) +{ + struct inode *inode = (struct inode *) foo; + + inode_init_once(inode); +} + +/* + * inode->i_lock must be held + */ +void __iget(struct inode *inode) +{ + atomic_inc(&inode->i_count); +} + +/* + * get additional reference to inode; caller must already hold one. + */ +void ihold(struct inode *inode) +{ + WARN_ON(atomic_inc_return(&inode->i_count) < 2); +} +EXPORT_SYMBOL(ihold); + +static void inode_lru_list_add(struct inode *inode) +{ + if (list_lru_add(&inode->i_sb->s_inode_lru, &inode->i_lru)) + this_cpu_inc(nr_unused); + else + inode->i_state |= I_REFERENCED; +} + +/* + * Add inode to LRU if needed (inode is unused and clean). + * + * Needs inode->i_lock held. + */ +void inode_add_lru(struct inode *inode) +{ + if (!(inode->i_state & (I_DIRTY_ALL | I_SYNC | + I_FREEING | I_WILL_FREE)) && + !atomic_read(&inode->i_count) && inode->i_sb->s_flags & SB_ACTIVE) + inode_lru_list_add(inode); +} + + +static void inode_lru_list_del(struct inode *inode) +{ + + if (list_lru_del(&inode->i_sb->s_inode_lru, &inode->i_lru)) + this_cpu_dec(nr_unused); +} + +/** + * inode_sb_list_add - add inode to the superblock list of inodes + * @inode: inode to add + */ +void inode_sb_list_add(struct inode *inode) +{ + spin_lock(&inode->i_sb->s_inode_list_lock); + list_add(&inode->i_sb_list, &inode->i_sb->s_inodes); + spin_unlock(&inode->i_sb->s_inode_list_lock); +} +EXPORT_SYMBOL_GPL(inode_sb_list_add); + +static inline void inode_sb_list_del(struct inode *inode) +{ + if (!list_empty(&inode->i_sb_list)) { + spin_lock(&inode->i_sb->s_inode_list_lock); + list_del_init(&inode->i_sb_list); + spin_unlock(&inode->i_sb->s_inode_list_lock); + } +} + +static unsigned long hash(struct super_block *sb, unsigned long hashval) +{ + unsigned long tmp; + + tmp = (hashval * (unsigned long)sb) ^ (GOLDEN_RATIO_PRIME + hashval) / + L1_CACHE_BYTES; + tmp = tmp ^ ((tmp ^ GOLDEN_RATIO_PRIME) >> i_hash_shift); + return tmp & i_hash_mask; +} + +/** + * __insert_inode_hash - hash an inode + * @inode: unhashed inode + * @hashval: unsigned long value used to locate this object in the + * inode_hashtable. + * + * Add an inode to the inode hash for this superblock. + */ +void __insert_inode_hash(struct inode *inode, unsigned long hashval) +{ + struct hlist_head *b = inode_hashtable + hash(inode->i_sb, hashval); + + spin_lock(&inode_hash_lock); + spin_lock(&inode->i_lock); + hlist_add_head_rcu(&inode->i_hash, b); + spin_unlock(&inode->i_lock); + spin_unlock(&inode_hash_lock); +} +EXPORT_SYMBOL(__insert_inode_hash); + +/** + * __remove_inode_hash - remove an inode from the hash + * @inode: inode to unhash + * + * Remove an inode from the superblock. + */ +void __remove_inode_hash(struct inode *inode) +{ + spin_lock(&inode_hash_lock); + spin_lock(&inode->i_lock); + hlist_del_init_rcu(&inode->i_hash); + spin_unlock(&inode->i_lock); + spin_unlock(&inode_hash_lock); +} +EXPORT_SYMBOL(__remove_inode_hash); + +void clear_inode(struct inode *inode) +{ + /* + * We have to cycle the i_pages lock here because reclaim can be in the + * process of removing the last page (in __delete_from_page_cache()) + * and we must not free the mapping under it. + */ + xa_lock_irq(&inode->i_data.i_pages); + BUG_ON(inode->i_data.nrpages); + BUG_ON(inode->i_data.nrexceptional); + xa_unlock_irq(&inode->i_data.i_pages); + BUG_ON(!list_empty(&inode->i_data.private_list)); + BUG_ON(!(inode->i_state & I_FREEING)); + BUG_ON(inode->i_state & I_CLEAR); + BUG_ON(!list_empty(&inode->i_wb_list)); + /* don't need i_lock here, no concurrent mods to i_state */ + inode->i_state = I_FREEING | I_CLEAR; +} +EXPORT_SYMBOL(clear_inode); + +/* + * Free the inode passed in, removing it from the lists it is still connected + * to. We remove any pages still attached to the inode and wait for any IO that + * is still in progress before finally destroying the inode. + * + * An inode must already be marked I_FREEING so that we avoid the inode being + * moved back onto lists if we race with other code that manipulates the lists + * (e.g. writeback_single_inode). The caller is responsible for setting this. + * + * An inode must already be removed from the LRU list before being evicted from + * the cache. This should occur atomically with setting the I_FREEING state + * flag, so no inodes here should ever be on the LRU when being evicted. + */ +static void evict(struct inode *inode) +{ + const struct super_operations *op = inode->i_sb->s_op; + + BUG_ON(!(inode->i_state & I_FREEING)); + BUG_ON(!list_empty(&inode->i_lru)); + + if (!list_empty(&inode->i_io_list)) + inode_io_list_del(inode); + + inode_sb_list_del(inode); + + /* + * Wait for flusher thread to be done with the inode so that filesystem + * does not start destroying it while writeback is still running. Since + * the inode has I_FREEING set, flusher thread won't start new work on + * the inode. We just have to wait for running writeback to finish. + */ + inode_wait_for_writeback(inode); + + if (op->evict_inode) { + op->evict_inode(inode); + } else { + truncate_inode_pages_final(&inode->i_data); + clear_inode(inode); + } + if (S_ISBLK(inode->i_mode) && inode->i_bdev) + bd_forget(inode); + if (S_ISCHR(inode->i_mode) && inode->i_cdev) + cd_forget(inode); + + remove_inode_hash(inode); + + spin_lock(&inode->i_lock); + wake_up_bit(&inode->i_state, __I_NEW); + BUG_ON(inode->i_state != (I_FREEING | I_CLEAR)); + spin_unlock(&inode->i_lock); + + destroy_inode(inode); +} + +/* + * dispose_list - dispose of the contents of a local list + * @head: the head of the list to free + * + * Dispose-list gets a local list with local inodes in it, so it doesn't + * need to worry about list corruption and SMP locks. + */ +static void dispose_list(struct list_head *head) +{ + while (!list_empty(head)) { + struct inode *inode; + + inode = list_first_entry(head, struct inode, i_lru); + list_del_init(&inode->i_lru); + + evict(inode); + cond_resched(); + } +} + +/** + * evict_inodes - evict all evictable inodes for a superblock + * @sb: superblock to operate on + * + * Make sure that no inodes with zero refcount are retained. This is + * called by superblock shutdown after having SB_ACTIVE flag removed, + * so any inode reaching zero refcount during or after that call will + * be immediately evicted. + */ +void evict_inodes(struct super_block *sb) +{ + struct inode *inode, *next; + LIST_HEAD(dispose); + +again: + spin_lock(&sb->s_inode_list_lock); + list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) { + if (atomic_read(&inode->i_count)) + continue; + + spin_lock(&inode->i_lock); + if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { + spin_unlock(&inode->i_lock); + continue; + } + + inode->i_state |= I_FREEING; + inode_lru_list_del(inode); + spin_unlock(&inode->i_lock); + list_add(&inode->i_lru, &dispose); + + /* + * We can have a ton of inodes to evict at unmount time given + * enough memory, check to see if we need to go to sleep for a + * bit so we don't livelock. + */ + if (need_resched()) { + spin_unlock(&sb->s_inode_list_lock); + cond_resched(); + dispose_list(&dispose); + goto again; + } + } + spin_unlock(&sb->s_inode_list_lock); + + dispose_list(&dispose); +} +EXPORT_SYMBOL_GPL(evict_inodes); + +/** + * invalidate_inodes - attempt to free all inodes on a superblock + * @sb: superblock to operate on + * @kill_dirty: flag to guide handling of dirty inodes + * + * Attempts to free all inodes for a given superblock. If there were any + * busy inodes return a non-zero value, else zero. + * If @kill_dirty is set, discard dirty inodes too, otherwise treat + * them as busy. + */ +int invalidate_inodes(struct super_block *sb, bool kill_dirty) +{ + int busy = 0; + struct inode *inode, *next; + LIST_HEAD(dispose); + +again: + spin_lock(&sb->s_inode_list_lock); + list_for_each_entry_safe(inode, next, &sb->s_inodes, i_sb_list) { + spin_lock(&inode->i_lock); + if (inode->i_state & (I_NEW | I_FREEING | I_WILL_FREE)) { + spin_unlock(&inode->i_lock); + continue; + } + if (inode->i_state & I_DIRTY_ALL && !kill_dirty) { + spin_unlock(&inode->i_lock); + busy = 1; + continue; + } + if (atomic_read(&inode->i_count)) { + spin_unlock(&inode->i_lock); + busy = 1; + continue; + } + + inode->i_state |= I_FREEING; + inode_lru_list_del(inode); + spin_unlock(&inode->i_lock); + list_add(&inode->i_lru, &dispose); + if (need_resched()) { + spin_unlock(&sb->s_inode_list_lock); + cond_resched(); + dispose_list(&dispose); + goto again; + } + } + spin_unlock(&sb->s_inode_list_lock); + + dispose_list(&dispose); + + return busy; +} + +/* + * Isolate the inode from the LRU in preparation for freeing it. + * + * Any inodes which are pinned purely because of attached pagecache have their + * pagecache removed. If the inode has metadata buffers attached to + * mapping->private_list then try to remove them. + * + * If the inode has the I_REFERENCED flag set, then it means that it has been + * used recently - the flag is set in iput_final(). When we encounter such an + * inode, clear the flag and move it to the back of the LRU so it gets another + * pass through the LRU before it gets reclaimed. This is necessary because of + * the fact we are doing lazy LRU updates to minimise lock contention so the + * LRU does not have strict ordering. Hence we don't want to reclaim inodes + * with this flag set because they are the inodes that are out of order. + */ +static enum lru_status inode_lru_isolate(struct list_head *item, + struct list_lru_one *lru, spinlock_t *lru_lock, void *arg) +{ + struct list_head *freeable = arg; + struct inode *inode = container_of(item, struct inode, i_lru); + + /* + * we are inverting the lru lock/inode->i_lock here, so use a trylock. + * If we fail to get the lock, just skip it. + */ + if (!spin_trylock(&inode->i_lock)) + return LRU_SKIP; + + /* + * Referenced or dirty inodes are still in use. Give them another pass + * through the LRU as we canot reclaim them now. + */ + if (atomic_read(&inode->i_count) || + (inode->i_state & ~I_REFERENCED)) { + list_lru_isolate(lru, &inode->i_lru); + spin_unlock(&inode->i_lock); + this_cpu_dec(nr_unused); + return LRU_REMOVED; + } + + /* recently referenced inodes get one more pass */ + if (inode->i_state & I_REFERENCED) { + inode->i_state &= ~I_REFERENCED; + spin_unlock(&inode->i_lock); + return LRU_ROTATE; + } + + if (inode_has_buffers(inode) || inode->i_data.nrpages) { + __iget(inode); + spin_unlock(&inode->i_lock); + spin_unlock(lru_lock); + if (remove_inode_buffers(inode)) { + unsigned long reap; + reap = invalidate_mapping_pages(&inode->i_data, 0, -1); + if (current_is_kswapd()) + __count_vm_events(KSWAPD_INODESTEAL, reap); + else + __count_vm_events(PGINODESTEAL, reap); + if (current->reclaim_state) + current->reclaim_state->reclaimed_slab += reap; + } + iput(inode); + spin_lock(lru_lock); + return LRU_RETRY; + } + + WARN_ON(inode->i_state & I_NEW); + inode->i_state |= I_FREEING; + list_lru_isolate_move(lru, &inode->i_lru, freeable); + spin_unlock(&inode->i_lock); + + this_cpu_dec(nr_unused); + return LRU_REMOVED; +} + +/* + * Walk the superblock inode LRU for freeable inodes and attempt to free them. + * This is called from the superblock shrinker function with a number of inodes + * to trim from the LRU. Inodes to be freed are moved to a temporary list and + * then are freed outside inode_lock by dispose_list(). + */ +long prune_icache_sb(struct super_block *sb, struct shrink_control *sc) +{ + LIST_HEAD(freeable); + long freed; + + freed = list_lru_shrink_walk(&sb->s_inode_lru, sc, + inode_lru_isolate, &freeable); + dispose_list(&freeable); + return freed; +} + +static void __wait_on_freeing_inode(struct inode *inode); +/* + * Called with the inode lock held. + */ +static struct inode *find_inode(struct super_block *sb, + struct hlist_head *head, + int (*test)(struct inode *, void *), + void *data) +{ + struct inode *inode = NULL; + +repeat: + hlist_for_each_entry(inode, head, i_hash) { + if (inode->i_sb != sb) + continue; + if (!test(inode, data)) + continue; + spin_lock(&inode->i_lock); + if (inode->i_state & (I_FREEING|I_WILL_FREE)) { + __wait_on_freeing_inode(inode); + goto repeat; + } + if (unlikely(inode->i_state & I_CREATING)) { + spin_unlock(&inode->i_lock); + return ERR_PTR(-ESTALE); + } + __iget(inode); + spin_unlock(&inode->i_lock); + return inode; + } + return NULL; +} + +/* + * find_inode_fast is the fast path version of find_inode, see the comment at + * iget_locked for details. + */ +static struct inode *find_inode_fast(struct super_block *sb, + struct hlist_head *head, unsigned long ino) +{ + struct inode *inode = NULL; + +repeat: + hlist_for_each_entry(inode, head, i_hash) { + if (inode->i_ino != ino) + continue; + if (inode->i_sb != sb) + continue; + spin_lock(&inode->i_lock); + if (inode->i_state & (I_FREEING|I_WILL_FREE)) { + __wait_on_freeing_inode(inode); + goto repeat; + } + if (unlikely(inode->i_state & I_CREATING)) { + spin_unlock(&inode->i_lock); + return ERR_PTR(-ESTALE); + } + __iget(inode); + spin_unlock(&inode->i_lock); + return inode; + } + return NULL; +} + +/* + * Each cpu owns a range of LAST_INO_BATCH numbers. + * 'shared_last_ino' is dirtied only once out of LAST_INO_BATCH allocations, + * to renew the exhausted range. + * + * This does not significantly increase overflow rate because every CPU can + * consume at most LAST_INO_BATCH-1 unused inode numbers. So there is + * NR_CPUS*(LAST_INO_BATCH-1) wastage. At 4096 and 1024, this is ~0.1% of the + * 2^32 range, and is a worst-case. Even a 50% wastage would only increase + * overflow rate by 2x, which does not seem too significant. + * + * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW + * error if st_ino won't fit in target struct field. Use 32bit counter + * here to attempt to avoid that. + */ +#define LAST_INO_BATCH 1024 +static DEFINE_PER_CPU(unsigned int, last_ino); + +unsigned int get_next_ino(void) +{ + unsigned int *p = &get_cpu_var(last_ino); + unsigned int res = *p; + +#ifdef CONFIG_SMP + if (unlikely((res & (LAST_INO_BATCH-1)) == 0)) { + static atomic_t shared_last_ino; + int next = atomic_add_return(LAST_INO_BATCH, &shared_last_ino); + + res = next - LAST_INO_BATCH; + } +#endif + + res++; + /* get_next_ino should not provide a 0 inode number */ + if (unlikely(!res)) + res++; + *p = res; + put_cpu_var(last_ino); + return res; +} +EXPORT_SYMBOL(get_next_ino); + +/** + * new_inode_pseudo - obtain an inode + * @sb: superblock + * + * Allocates a new inode for given superblock. + * Inode wont be chained in superblock s_inodes list + * This means : + * - fs can't be unmount + * - quotas, fsnotify, writeback can't work + */ +struct inode *new_inode_pseudo(struct super_block *sb) +{ + struct inode *inode = alloc_inode(sb); + + if (inode) { + spin_lock(&inode->i_lock); + inode->i_state = 0; + spin_unlock(&inode->i_lock); + INIT_LIST_HEAD(&inode->i_sb_list); + } + return inode; +} + +/** + * new_inode - obtain an inode + * @sb: superblock + * + * Allocates a new inode for given superblock. The default gfp_mask + * for allocations related to inode->i_mapping is GFP_HIGHUSER_MOVABLE. + * If HIGHMEM pages are unsuitable or it is known that pages allocated + * for the page cache are not reclaimable or migratable, + * mapping_set_gfp_mask() must be called with suitable flags on the + * newly created inode's mapping + * + */ +struct inode *new_inode(struct super_block *sb) +{ + struct inode *inode; + + spin_lock_prefetch(&sb->s_inode_list_lock); + + inode = new_inode_pseudo(sb); + if (inode) + inode_sb_list_add(inode); + return inode; +} +EXPORT_SYMBOL(new_inode); + +#ifdef CONFIG_DEBUG_LOCK_ALLOC +void lockdep_annotate_inode_mutex_key(struct inode *inode) +{ + if (S_ISDIR(inode->i_mode)) { + struct file_system_type *type = inode->i_sb->s_type; + + /* Set new key only if filesystem hasn't already changed it */ + if (lockdep_match_class(&inode->i_rwsem, &type->i_mutex_key)) { + /* + * ensure nobody is actually holding i_mutex + */ + // mutex_destroy(&inode->i_mutex); + init_rwsem(&inode->i_rwsem); + lockdep_set_class(&inode->i_rwsem, + &type->i_mutex_dir_key); + } + } +} +EXPORT_SYMBOL(lockdep_annotate_inode_mutex_key); +#endif + +/** + * unlock_new_inode - clear the I_NEW state and wake up any waiters + * @inode: new inode to unlock + * + * Called when the inode is fully initialised to clear the new state of the + * inode and wake up anyone waiting for the inode to finish initialisation. + */ +void unlock_new_inode(struct inode *inode) +{ + lockdep_annotate_inode_mutex_key(inode); + spin_lock(&inode->i_lock); + WARN_ON(!(inode->i_state & I_NEW)); + inode->i_state &= ~I_NEW & ~I_CREATING; + smp_mb(); + wake_up_bit(&inode->i_state, __I_NEW); + spin_unlock(&inode->i_lock); +} +EXPORT_SYMBOL(unlock_new_inode); + +void discard_new_inode(struct inode *inode) +{ + lockdep_annotate_inode_mutex_key(inode); + spin_lock(&inode->i_lock); + WARN_ON(!(inode->i_state & I_NEW)); + inode->i_state &= ~I_NEW; + smp_mb(); + wake_up_bit(&inode->i_state, __I_NEW); + spin_unlock(&inode->i_lock); + iput(inode); +} +EXPORT_SYMBOL(discard_new_inode); + +/** + * lock_two_inodes - lock two inodes (may be regular files but also dirs) + * + * Lock any non-NULL argument. The caller must make sure that if he is passing + * in two directories, one is not ancestor of the other. Zero, one or two + * objects may be locked by this function. + * + * @inode1: first inode to lock + * @inode2: second inode to lock + * @subclass1: inode lock subclass for the first lock obtained + * @subclass2: inode lock subclass for the second lock obtained + */ +void lock_two_inodes(struct inode *inode1, struct inode *inode2, + unsigned subclass1, unsigned subclass2) +{ + if (!inode1 || !inode2) { + /* + * Make sure @subclass1 will be used for the acquired lock. + * This is not strictly necessary (no current caller cares) but + * let's keep things consistent. + */ + if (!inode1) + swap(inode1, inode2); + goto lock; + } + + /* + * If one object is directory and the other is not, we must make sure + * to lock directory first as the other object may be its child. + */ + if (S_ISDIR(inode2->i_mode) == S_ISDIR(inode1->i_mode)) { + if (inode1 > inode2) + swap(inode1, inode2); + } else if (!S_ISDIR(inode1->i_mode)) + swap(inode1, inode2); +lock: + if (inode1) + inode_lock_nested(inode1, subclass1); + if (inode2 && inode2 != inode1) + inode_lock_nested(inode2, subclass2); +} + +/** + * lock_two_nondirectories - take two i_mutexes on non-directory objects + * + * Lock any non-NULL argument that is not a directory. + * Zero, one or two objects may be locked by this function. + * + * @inode1: first inode to lock + * @inode2: second inode to lock + */ +void lock_two_nondirectories(struct inode *inode1, struct inode *inode2) +{ + if (inode1 > inode2) + swap(inode1, inode2); + + if (inode1 && !S_ISDIR(inode1->i_mode)) + inode_lock(inode1); + if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1) + inode_lock_nested(inode2, I_MUTEX_NONDIR2); +} +EXPORT_SYMBOL(lock_two_nondirectories); + +/** + * unlock_two_nondirectories - release locks from lock_two_nondirectories() + * @inode1: first inode to unlock + * @inode2: second inode to unlock + */ +void unlock_two_nondirectories(struct inode *inode1, struct inode *inode2) +{ + if (inode1 && !S_ISDIR(inode1->i_mode)) + inode_unlock(inode1); + if (inode2 && !S_ISDIR(inode2->i_mode) && inode2 != inode1) + inode_unlock(inode2); +} +EXPORT_SYMBOL(unlock_two_nondirectories); + +/** + * inode_insert5 - obtain an inode from a mounted file system + * @inode: pre-allocated inode to use for insert to cache + * @hashval: hash value (usually inode number) to get + * @test: callback used for comparisons between inodes + * @set: callback used to initialize a new struct inode + * @data: opaque data pointer to pass to @test and @set + * + * Search for the inode specified by @hashval and @data in the inode cache, + * and if present it is return it with an increased reference count. This is + * a variant of iget5_locked() for callers that don't want to fail on memory + * allocation of inode. + * + * If the inode is not in cache, insert the pre-allocated inode to cache and + * return it locked, hashed, and with the I_NEW flag set. The file system gets + * to fill it in before unlocking it via unlock_new_inode(). + * + * Note both @test and @set are called with the inode_hash_lock held, so can't + * sleep. + */ +struct inode *inode_insert5(struct inode *inode, unsigned long hashval, + int (*test)(struct inode *, void *), + int (*set)(struct inode *, void *), void *data) +{ + struct hlist_head *head = inode_hashtable + hash(inode->i_sb, hashval); + struct inode *old; + bool creating = inode->i_state & I_CREATING; + +again: + spin_lock(&inode_hash_lock); + old = find_inode(inode->i_sb, head, test, data); + if (unlikely(old)) { + /* + * Uhhuh, somebody else created the same inode under us. + * Use the old inode instead of the preallocated one. + */ + spin_unlock(&inode_hash_lock); + if (IS_ERR(old)) + return NULL; + wait_on_inode(old); + if (unlikely(inode_unhashed(old))) { + iput(old); + goto again; + } + return old; + } + + if (set && unlikely(set(inode, data))) { + inode = NULL; + goto unlock; + } + + /* + * Return the locked inode with I_NEW set, the + * caller is responsible for filling in the contents + */ + spin_lock(&inode->i_lock); + inode->i_state |= I_NEW; + hlist_add_head_rcu(&inode->i_hash, head); + spin_unlock(&inode->i_lock); + if (!creating) + inode_sb_list_add(inode); +unlock: + spin_unlock(&inode_hash_lock); + + return inode; +} +EXPORT_SYMBOL(inode_insert5); + +/** + * iget5_locked - obtain an inode from a mounted file system + * @sb: super block of file system + * @hashval: hash value (usually inode number) to get + * @test: callback used for comparisons between inodes + * @set: callback used to initialize a new struct inode + * @data: opaque data pointer to pass to @test and @set + * + * Search for the inode specified by @hashval and @data in the inode cache, + * and if present it is return it with an increased reference count. This is + * a generalized version of iget_locked() for file systems where the inode + * number is not sufficient for unique identification of an inode. + * + * If the inode is not in cache, allocate a new inode and return it locked, + * hashed, and with the I_NEW flag set. The file system gets to fill it in + * before unlocking it via unlock_new_inode(). + * + * Note both @test and @set are called with the inode_hash_lock held, so can't + * sleep. + */ +struct inode *iget5_locked(struct super_block *sb, unsigned long hashval, + int (*test)(struct inode *, void *), + int (*set)(struct inode *, void *), void *data) +{ + struct inode *inode = ilookup5(sb, hashval, test, data); + + if (!inode) { + struct inode *new = alloc_inode(sb); + + if (new) { + new->i_state = 0; + inode = inode_insert5(new, hashval, test, set, data); + if (unlikely(inode != new)) + destroy_inode(new); + } + } + return inode; +} +EXPORT_SYMBOL(iget5_locked); + +/** + * iget_locked - obtain an inode from a mounted file system + * @sb: super block of file system + * @ino: inode number to get + * + * Search for the inode specified by @ino in the inode cache and if present + * return it with an increased reference count. This is for file systems + * where the inode number is sufficient for unique identification of an inode. + * + * If the inode is not in cache, allocate a new inode and return it locked, + * hashed, and with the I_NEW flag set. The file system gets to fill it in + * before unlocking it via unlock_new_inode(). + */ +struct inode *iget_locked(struct super_block *sb, unsigned long ino) +{ + struct hlist_head *head = inode_hashtable + hash(sb, ino); + struct inode *inode; +again: + spin_lock(&inode_hash_lock); + inode = find_inode_fast(sb, head, ino); + spin_unlock(&inode_hash_lock); + if (inode) { + if (IS_ERR(inode)) + return NULL; + wait_on_inode(inode); + if (unlikely(inode_unhashed(inode))) { + iput(inode); + goto again; + } + return inode; + } + + inode = alloc_inode(sb); + if (inode) { + struct inode *old; + + spin_lock(&inode_hash_lock); + /* We released the lock, so.. */ + old = find_inode_fast(sb, head, ino); + if (!old) { + inode->i_ino = ino; + spin_lock(&inode->i_lock); + inode->i_state = I_NEW; + hlist_add_head_rcu(&inode->i_hash, head); + spin_unlock(&inode->i_lock); + inode_sb_list_add(inode); + spin_unlock(&inode_hash_lock); + + /* Return the locked inode with I_NEW set, the + * caller is responsible for filling in the contents + */ + return inode; + } + + /* + * Uhhuh, somebody else created the same inode under + * us. Use the old inode instead of the one we just + * allocated. + */ + spin_unlock(&inode_hash_lock); + destroy_inode(inode); + if (IS_ERR(old)) + return NULL; + inode = old; + wait_on_inode(inode); + if (unlikely(inode_unhashed(inode))) { + iput(inode); + goto again; + } + } + return inode; +} +EXPORT_SYMBOL(iget_locked); + +/* + * search the inode cache for a matching inode number. + * If we find one, then the inode number we are trying to + * allocate is not unique and so we should not use it. + * + * Returns 1 if the inode number is unique, 0 if it is not. + */ +static int test_inode_iunique(struct super_block *sb, unsigned long ino) +{ + struct hlist_head *b = inode_hashtable + hash(sb, ino); + struct inode *inode; + + hlist_for_each_entry_rcu(inode, b, i_hash) { + if (inode->i_ino == ino && inode->i_sb == sb) + return 0; + } + return 1; +} + +/** + * iunique - get a unique inode number + * @sb: superblock + * @max_reserved: highest reserved inode number + * + * Obtain an inode number that is unique on the system for a given + * superblock. This is used by file systems that have no natural + * permanent inode numbering system. An inode number is returned that + * is higher than the reserved limit but unique. + * + * BUGS: + * With a large number of inodes live on the file system this function + * currently becomes quite slow. + */ +ino_t iunique(struct super_block *sb, ino_t max_reserved) +{ + /* + * On a 32bit, non LFS stat() call, glibc will generate an EOVERFLOW + * error if st_ino won't fit in target struct field. Use 32bit counter + * here to attempt to avoid that. + */ + static DEFINE_SPINLOCK(iunique_lock); + static unsigned int counter; + ino_t res; + + rcu_read_lock(); + spin_lock(&iunique_lock); + do { + if (counter <= max_reserved) + counter = max_reserved + 1; + res = counter++; + } while (!test_inode_iunique(sb, res)); + spin_unlock(&iunique_lock); + rcu_read_unlock(); + + return res; +} +EXPORT_SYMBOL(iunique); + +struct inode *igrab(struct inode *inode) +{ + spin_lock(&inode->i_lock); + if (!(inode->i_state & (I_FREEING|I_WILL_FREE))) { + __iget(inode); + spin_unlock(&inode->i_lock); + } else { + spin_unlock(&inode->i_lock); + /* + * Handle the case where s_op->clear_inode is not been + * called yet, and somebody is calling igrab + * while the inode is getting freed. + */ + inode = NULL; + } + return inode; +} +EXPORT_SYMBOL(igrab); + +/** + * ilookup5_nowait - search for an inode in the inode cache + * @sb: super block of file system to search + * @hashval: hash value (usually inode number) to search for + * @test: callback used for comparisons between inodes + * @data: opaque data pointer to pass to @test + * + * Search for the inode specified by @hashval and @data in the inode cache. + * If the inode is in the cache, the inode is returned with an incremented + * reference count. + * + * Note: I_NEW is not waited upon so you have to be very careful what you do + * with the returned inode. You probably should be using ilookup5() instead. + * + * Note2: @test is called with the inode_hash_lock held, so can't sleep. + */ +struct inode *ilookup5_nowait(struct super_block *sb, unsigned long hashval, + int (*test)(struct inode *, void *), void *data) +{ + struct hlist_head *head = inode_hashtable + hash(sb, hashval); + struct inode *inode; + + spin_lock(&inode_hash_lock); + inode = find_inode(sb, head, test, data); + spin_unlock(&inode_hash_lock); + + return IS_ERR(inode) ? NULL : inode; +} +EXPORT_SYMBOL(ilookup5_nowait); + +/** + * ilookup5 - search for an inode in the inode cache + * @sb: super block of file system to search + * @hashval: hash value (usually inode number) to search for + * @test: callback used for comparisons between inodes + * @data: opaque data pointer to pass to @test + * + * Search for the inode specified by @hashval and @data in the inode cache, + * and if the inode is in the cache, return the inode with an incremented + * reference count. Waits on I_NEW before returning the inode. + * returned with an incremented reference count. + * + * This is a generalized version of ilookup() for file systems where the + * inode number is not sufficient for unique identification of an inode. + * + * Note: @test is called with the inode_hash_lock held, so can't sleep. + */ +struct inode *ilookup5(struct super_block *sb, unsigned long hashval, + int (*test)(struct inode *, void *), void *data) +{ + struct inode *inode; +again: + inode = ilookup5_nowait(sb, hashval, test, data); + if (inode) { + wait_on_inode(inode); + if (unlikely(inode_unhashed(inode))) { + iput(inode); + goto again; + } + } + return inode; +} +EXPORT_SYMBOL(ilookup5); + +/** + * ilookup - search for an inode in the inode cache + * @sb: super block of file system to search + * @ino: inode number to search for + * + * Search for the inode @ino in the inode cache, and if the inode is in the + * cache, the inode is returned with an incremented reference count. + */ +struct inode *ilookup(struct super_block *sb, unsigned long ino) +{ + struct hlist_head *head = inode_hashtable + hash(sb, ino); + struct inode *inode; +again: + spin_lock(&inode_hash_lock); + inode = find_inode_fast(sb, head, ino); + spin_unlock(&inode_hash_lock); + + if (inode) { + if (IS_ERR(inode)) + return NULL; + wait_on_inode(inode); + if (unlikely(inode_unhashed(inode))) { + iput(inode); + goto again; + } + } + return inode; +} +EXPORT_SYMBOL(ilookup); + +/** + * find_inode_nowait - find an inode in the inode cache + * @sb: super block of file system to search + * @hashval: hash value (usually inode number) to search for + * @match: callback used for comparisons between inodes + * @data: opaque data pointer to pass to @match + * + * Search for the inode specified by @hashval and @data in the inode + * cache, where the helper function @match will return 0 if the inode + * does not match, 1 if the inode does match, and -1 if the search + * should be stopped. The @match function must be responsible for + * taking the i_lock spin_lock and checking i_state for an inode being + * freed or being initialized, and incrementing the reference count + * before returning 1. It also must not sleep, since it is called with + * the inode_hash_lock spinlock held. + * + * This is a even more generalized version of ilookup5() when the + * function must never block --- find_inode() can block in + * __wait_on_freeing_inode() --- or when the caller can not increment + * the reference count because the resulting iput() might cause an + * inode eviction. The tradeoff is that the @match funtion must be + * very carefully implemented. + */ +struct inode *find_inode_nowait(struct super_block *sb, + unsigned long hashval, + int (*match)(struct inode *, unsigned long, + void *), + void *data) +{ + struct hlist_head *head = inode_hashtable + hash(sb, hashval); + struct inode *inode, *ret_inode = NULL; + int mval; + + spin_lock(&inode_hash_lock); + hlist_for_each_entry(inode, head, i_hash) { + if (inode->i_sb != sb) + continue; + mval = match(inode, hashval, data); + if (mval == 0) + continue; + if (mval == 1) + ret_inode = inode; + goto out; + } +out: + spin_unlock(&inode_hash_lock); + return ret_inode; +} +EXPORT_SYMBOL(find_inode_nowait); + +/** + * find_inode_rcu - find an inode in the inode cache + * @sb: Super block of file system to search + * @hashval: Key to hash + * @test: Function to test match on an inode + * @data: Data for test function + * + * Search for the inode specified by @hashval and @data in the inode cache, + * where the helper function @test will return 0 if the inode does not match + * and 1 if it does. The @test function must be responsible for taking the + * i_lock spin_lock and checking i_state for an inode being freed or being + * initialized. + * + * If successful, this will return the inode for which the @test function + * returned 1 and NULL otherwise. + * + * The @test function is not permitted to take a ref on any inode presented. + * It is also not permitted to sleep. + * + * The caller must hold the RCU read lock. + */ +struct inode *find_inode_rcu(struct super_block *sb, unsigned long hashval, + int (*test)(struct inode *, void *), void *data) +{ + struct hlist_head *head = inode_hashtable + hash(sb, hashval); + struct inode *inode; + + RCU_LOCKDEP_WARN(!rcu_read_lock_held(), + "suspicious find_inode_rcu() usage"); + + hlist_for_each_entry_rcu(inode, head, i_hash) { + if (inode->i_sb == sb && + !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE)) && + test(inode, data)) + return inode; + } + return NULL; +} +EXPORT_SYMBOL(find_inode_rcu); + +/** + * find_inode_by_rcu - Find an inode in the inode cache + * @sb: Super block of file system to search + * @ino: The inode number to match + * + * Search for the inode specified by @hashval and @data in the inode cache, + * where the helper function @test will return 0 if the inode does not match + * and 1 if it does. The @test function must be responsible for taking the + * i_lock spin_lock and checking i_state for an inode being freed or being + * initialized. + * + * If successful, this will return the inode for which the @test function + * returned 1 and NULL otherwise. + * + * The @test function is not permitted to take a ref on any inode presented. + * It is also not permitted to sleep. + * + * The caller must hold the RCU read lock. + */ +struct inode *find_inode_by_ino_rcu(struct super_block *sb, + unsigned long ino) +{ + struct hlist_head *head = inode_hashtable + hash(sb, ino); + struct inode *inode; + + RCU_LOCKDEP_WARN(!rcu_read_lock_held(), + "suspicious find_inode_by_ino_rcu() usage"); + + hlist_for_each_entry_rcu(inode, head, i_hash) { + if (inode->i_ino == ino && + inode->i_sb == sb && + !(READ_ONCE(inode->i_state) & (I_FREEING | I_WILL_FREE))) + return inode; + } + return NULL; +} +EXPORT_SYMBOL(find_inode_by_ino_rcu); + +int insert_inode_locked(struct inode *inode) +{ + struct super_block *sb = inode->i_sb; + ino_t ino = inode->i_ino; + struct hlist_head *head = inode_hashtable + hash(sb, ino); + + while (1) { + struct inode *old = NULL; + spin_lock(&inode_hash_lock); + hlist_for_each_entry(old, head, i_hash) { + if (old->i_ino != ino) + continue; + if (old->i_sb != sb) + continue; + spin_lock(&old->i_lock); + if (old->i_state & (I_FREEING|I_WILL_FREE)) { + spin_unlock(&old->i_lock); + continue; + } + break; + } + if (likely(!old)) { + spin_lock(&inode->i_lock); + inode->i_state |= I_NEW | I_CREATING; + hlist_add_head_rcu(&inode->i_hash, head); + spin_unlock(&inode->i_lock); + spin_unlock(&inode_hash_lock); + return 0; + } + if (unlikely(old->i_state & I_CREATING)) { + spin_unlock(&old->i_lock); + spin_unlock(&inode_hash_lock); + return -EBUSY; + } + __iget(old); + spin_unlock(&old->i_lock); + spin_unlock(&inode_hash_lock); + wait_on_inode(old); + if (unlikely(!inode_unhashed(old))) { + iput(old); + return -EBUSY; + } + iput(old); + } +} +EXPORT_SYMBOL(insert_inode_locked); + +int insert_inode_locked4(struct inode *inode, unsigned long hashval, + int (*test)(struct inode *, void *), void *data) +{ + struct inode *old; + + inode->i_state |= I_CREATING; + old = inode_insert5(inode, hashval, test, NULL, data); + + if (old != inode) { + iput(old); + return -EBUSY; + } + return 0; +} +EXPORT_SYMBOL(insert_inode_locked4); + + +int generic_delete_inode(struct inode *inode) +{ + return 1; +} +EXPORT_SYMBOL(generic_delete_inode); + +/* + * Called when we're dropping the last reference + * to an inode. + * + * Call the FS "drop_inode()" function, defaulting to + * the legacy UNIX filesystem behaviour. If it tells + * us to evict inode, do so. Otherwise, retain inode + * in cache if fs is alive, sync and evict if fs is + * shutting down. + */ +static void iput_final(struct inode *inode) +{ + struct super_block *sb = inode->i_sb; + const struct super_operations *op = inode->i_sb->s_op; + unsigned long state; + int drop; + + WARN_ON(inode->i_state & I_NEW); + + if (op->drop_inode) + drop = op->drop_inode(inode); + else + drop = generic_drop_inode(inode); + + if (!drop && + !(inode->i_state & I_DONTCACHE) && + (sb->s_flags & SB_ACTIVE)) { + inode_add_lru(inode); + spin_unlock(&inode->i_lock); + return; + } + + state = inode->i_state; + if (!drop) { + WRITE_ONCE(inode->i_state, state | I_WILL_FREE); + spin_unlock(&inode->i_lock); + + write_inode_now(inode, 1); + + spin_lock(&inode->i_lock); + state = inode->i_state; + WARN_ON(state & I_NEW); + state &= ~I_WILL_FREE; + } + + WRITE_ONCE(inode->i_state, state | I_FREEING); + if (!list_empty(&inode->i_lru)) + inode_lru_list_del(inode); + spin_unlock(&inode->i_lock); + + evict(inode); +} + +/** + * iput - put an inode + * @inode: inode to put + * + * Puts an inode, dropping its usage count. If the inode use count hits + * zero, the inode is then freed and may also be destroyed. + * + * Consequently, iput() can sleep. + */ +void iput(struct inode *inode) +{ + if (!inode) + return; + BUG_ON(inode->i_state & I_CLEAR); +retry: + if (atomic_dec_and_lock(&inode->i_count, &inode->i_lock)) { + if (inode->i_nlink && (inode->i_state & I_DIRTY_TIME)) { + atomic_inc(&inode->i_count); + spin_unlock(&inode->i_lock); + trace_writeback_lazytime_iput(inode); + mark_inode_dirty_sync(inode); + goto retry; + } + iput_final(inode); + } +} +EXPORT_SYMBOL(iput); + +#ifdef CONFIG_BLOCK +/** + * bmap - find a block number in a file + * @inode: inode owning the block number being requested + * @block: pointer containing the block to find + * + * Replaces the value in ``*block`` with the block number on the device holding + * corresponding to the requested block number in the file. + * That is, asked for block 4 of inode 1 the function will replace the + * 4 in ``*block``, with disk block relative to the disk start that holds that + * block of the file. + * + * Returns -EINVAL in case of error, 0 otherwise. If mapping falls into a + * hole, returns 0 and ``*block`` is also set to 0. + */ +int bmap(struct inode *inode, sector_t *block) +{ + if (!inode->i_mapping->a_ops->bmap) + return -EINVAL; + + *block = inode->i_mapping->a_ops->bmap(inode->i_mapping, *block); + return 0; +} +EXPORT_SYMBOL(bmap); +#endif + +/* + * With relative atime, only update atime if the previous atime is + * earlier than either the ctime or mtime or if at least a day has + * passed since the last atime update. + */ +static int relatime_need_update(struct vfsmount *mnt, struct inode *inode, + struct timespec64 now) +{ + + if (!(mnt->mnt_flags & MNT_RELATIME)) + return 1; + /* + * Is mtime younger than atime? If yes, update atime: + */ + if (timespec64_compare(&inode->i_mtime, &inode->i_atime) >= 0) + return 1; + /* + * Is ctime younger than atime? If yes, update atime: + */ + if (timespec64_compare(&inode->i_ctime, &inode->i_atime) >= 0) + return 1; + + /* + * Is the previous atime value older than a day? If yes, + * update atime: + */ + if ((long)(now.tv_sec - inode->i_atime.tv_sec) >= 24*60*60) + return 1; + /* + * Good, we can skip the atime update: + */ + return 0; +} + +int generic_update_time(struct inode *inode, struct timespec64 *time, int flags) +{ + int iflags = I_DIRTY_TIME; + bool dirty = false; + + if (flags & S_ATIME) + inode->i_atime = *time; + if (flags & S_VERSION) + dirty = inode_maybe_inc_iversion(inode, false); + if (flags & S_CTIME) + inode->i_ctime = *time; + if (flags & S_MTIME) + inode->i_mtime = *time; + if ((flags & (S_ATIME | S_CTIME | S_MTIME)) && + !(inode->i_sb->s_flags & SB_LAZYTIME)) + dirty = true; + + if (dirty) + iflags |= I_DIRTY_SYNC; + __mark_inode_dirty(inode, iflags); + return 0; +} +EXPORT_SYMBOL(generic_update_time); + +/* + * This does the actual work of updating an inodes time or version. Must have + * had called mnt_want_write() before calling this. + */ +int inode_update_time(struct inode *inode, struct timespec64 *time, int flags) +{ + if (inode->i_op->update_time) + return inode->i_op->update_time(inode, time, flags); + return generic_update_time(inode, time, flags); +} +EXPORT_SYMBOL(inode_update_time); + +/** + * touch_atime - update the access time + * @path: the &struct path to update + * @inode: inode to update + * + * Update the accessed time on an inode and mark it for writeback. + * This function automatically handles read only file systems and media, + * as well as the "noatime" flag and inode specific "noatime" markers. + */ +bool atime_needs_update(const struct path *path, struct inode *inode) +{ + struct vfsmount *mnt = path->mnt; + struct timespec64 now; + + if (inode->i_flags & S_NOATIME) + return false; + + /* Atime updates will likely cause i_uid and i_gid to be written + * back improprely if their true value is unknown to the vfs. + */ + if (HAS_UNMAPPED_ID(inode)) + return false; + + if (IS_NOATIME(inode)) + return false; + if ((inode->i_sb->s_flags & SB_NODIRATIME) && S_ISDIR(inode->i_mode)) + return false; + + if (mnt->mnt_flags & MNT_NOATIME) + return false; + if ((mnt->mnt_flags & MNT_NODIRATIME) && S_ISDIR(inode->i_mode)) + return false; + + now = current_time(inode); + + if (!relatime_need_update(mnt, inode, now)) + return false; + + if (timespec64_equal(&inode->i_atime, &now)) + return false; + + return true; +} + +void touch_atime(const struct path *path) +{ + struct vfsmount *mnt = path->mnt; + struct inode *inode = d_inode(path->dentry); + struct timespec64 now; + + if (!atime_needs_update(path, inode)) + return; + + if (!sb_start_write_trylock(inode->i_sb)) + return; + + if (__mnt_want_write(mnt) != 0) + goto skip_update; + /* + * File systems can error out when updating inodes if they need to + * allocate new space to modify an inode (such is the case for + * Btrfs), but since we touch atime while walking down the path we + * really don't care if we failed to update the atime of the file, + * so just ignore the return value. + * We may also fail on filesystems that have the ability to make parts + * of the fs read only, e.g. subvolumes in Btrfs. + */ + now = current_time(inode); + inode_update_time(inode, &now, S_ATIME); + __mnt_drop_write(mnt); +skip_update: + sb_end_write(inode->i_sb); +} +EXPORT_SYMBOL(touch_atime); + +/* + * Return mask of changes for notify_change() that need to be done as a + * response to write or truncate. Return 0 if nothing has to be changed. + * Negative value on error (change should be denied). + */ +int dentry_needs_remove_privs(struct dentry *dentry) +{ + struct inode *inode = d_inode(dentry); + int mask = 0; + int ret; + + if (IS_NOSEC(inode)) + return 0; + + mask = setattr_should_drop_suidgid(inode); + ret = security_inode_need_killpriv(dentry); + if (ret < 0) + return ret; + if (ret) + mask |= ATTR_KILL_PRIV; + return mask; +} + +static int __remove_privs(struct dentry *dentry, int kill) +{ + struct iattr newattrs; + + newattrs.ia_valid = ATTR_FORCE | kill; + /* + * Note we call this on write, so notify_change will not + * encounter any conflicting delegations: + */ + return notify_change(dentry, &newattrs, NULL); +} + +/* + * Remove special file priviledges (suid, capabilities) when file is written + * to or truncated. + */ +int file_remove_privs(struct file *file) +{ + struct dentry *dentry = file_dentry(file); + struct inode *inode = file_inode(file); + int kill; + int error = 0; + + /* + * Fast path for nothing security related. + * As well for non-regular files, e.g. blkdev inodes. + * For example, blkdev_write_iter() might get here + * trying to remove privs which it is not allowed to. + */ + if (IS_NOSEC(inode) || !S_ISREG(inode->i_mode)) + return 0; + + kill = dentry_needs_remove_privs(dentry); + if (kill < 0) + return kill; + if (kill) + error = __remove_privs(dentry, kill); + if (!error) + inode_has_no_xattr(inode); + + return error; +} +EXPORT_SYMBOL(file_remove_privs); + +/** + * file_update_time - update mtime and ctime time + * @file: file accessed + * + * Update the mtime and ctime members of an inode and mark the inode + * for writeback. Note that this function is meant exclusively for + * usage in the file write path of filesystems, and filesystems may + * choose to explicitly ignore update via this function with the + * S_NOCMTIME inode flag, e.g. for network filesystem where these + * timestamps are handled by the server. This can return an error for + * file systems who need to allocate space in order to update an inode. + */ + +int file_update_time(struct file *file) +{ + struct inode *inode = file_inode(file); + struct timespec64 now; + int sync_it = 0; + int ret; + + /* First try to exhaust all avenues to not sync */ + if (IS_NOCMTIME(inode)) + return 0; + + now = current_time(inode); + if (!timespec64_equal(&inode->i_mtime, &now)) + sync_it = S_MTIME; + + if (!timespec64_equal(&inode->i_ctime, &now)) + sync_it |= S_CTIME; + + if (IS_I_VERSION(inode) && inode_iversion_need_inc(inode)) + sync_it |= S_VERSION; + + if (!sync_it) + return 0; + + /* Finally allowed to write? Takes lock. */ + if (__mnt_want_write_file(file)) + return 0; + + ret = inode_update_time(inode, &now, sync_it); + __mnt_drop_write_file(file); + + return ret; +} +EXPORT_SYMBOL(file_update_time); + +/* Caller must hold the file's inode lock */ +int file_modified(struct file *file) +{ + int err; + + /* + * Clear the security bits if the process is not being run by root. + * This keeps people from modifying setuid and setgid binaries. + */ + err = file_remove_privs(file); + if (err) + return err; + + if (unlikely(file->f_mode & FMODE_NOCMTIME)) + return 0; + + return file_update_time(file); +} +EXPORT_SYMBOL(file_modified); + +int inode_needs_sync(struct inode *inode) +{ + if (IS_SYNC(inode)) + return 1; + if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) + return 1; + return 0; +} +EXPORT_SYMBOL(inode_needs_sync); + +/* + * If we try to find an inode in the inode hash while it is being + * deleted, we have to wait until the filesystem completes its + * deletion before reporting that it isn't found. This function waits + * until the deletion _might_ have completed. Callers are responsible + * to recheck inode state. + * + * It doesn't matter if I_NEW is not set initially, a call to + * wake_up_bit(&inode->i_state, __I_NEW) after removing from the hash list + * will DTRT. + */ +static void __wait_on_freeing_inode(struct inode *inode) +{ + wait_queue_head_t *wq; + DEFINE_WAIT_BIT(wait, &inode->i_state, __I_NEW); + wq = bit_waitqueue(&inode->i_state, __I_NEW); + prepare_to_wait(wq, &wait.wq_entry, TASK_UNINTERRUPTIBLE); + spin_unlock(&inode->i_lock); + spin_unlock(&inode_hash_lock); + schedule(); + finish_wait(wq, &wait.wq_entry); + spin_lock(&inode_hash_lock); +} + +static __initdata unsigned long ihash_entries; +static int __init set_ihash_entries(char *str) +{ + if (!str) + return 0; + ihash_entries = simple_strtoul(str, &str, 0); + return 1; +} +__setup("ihash_entries=", set_ihash_entries); + +/* + * Initialize the waitqueues and inode hash table. + */ +void __init inode_init_early(void) +{ + /* If hashes are distributed across NUMA nodes, defer + * hash allocation until vmalloc space is available. + */ + if (hashdist) + return; + + inode_hashtable = + alloc_large_system_hash("Inode-cache", + sizeof(struct hlist_head), + ihash_entries, + 14, + HASH_EARLY | HASH_ZERO, + &i_hash_shift, + &i_hash_mask, + 0, + 0); +} + +void __init inode_init(void) +{ + /* inode slab cache */ + inode_cachep = kmem_cache_create("inode_cache", + sizeof(struct inode), + 0, + (SLAB_RECLAIM_ACCOUNT|SLAB_PANIC| + SLAB_MEM_SPREAD|SLAB_ACCOUNT), + init_once); + + /* Hash may have been set up in inode_init_early */ + if (!hashdist) + return; + + inode_hashtable = + alloc_large_system_hash("Inode-cache", + sizeof(struct hlist_head), + ihash_entries, + 14, + HASH_ZERO, + &i_hash_shift, + &i_hash_mask, + 0, + 0); +} + +void init_special_inode(struct inode *inode, umode_t mode, dev_t rdev) +{ + inode->i_mode = mode; + if (S_ISCHR(mode)) { + inode->i_fop = &def_chr_fops; + inode->i_rdev = rdev; + } else if (S_ISBLK(mode)) { + inode->i_fop = &def_blk_fops; + inode->i_rdev = rdev; + } else if (S_ISFIFO(mode)) + inode->i_fop = &pipefifo_fops; + else if (S_ISSOCK(mode)) + ; /* leave it no_open_fops */ + else + printk(KERN_DEBUG "init_special_inode: bogus i_mode (%o) for" + " inode %s:%lu\n", mode, inode->i_sb->s_id, + inode->i_ino); +} +EXPORT_SYMBOL(init_special_inode); + +/** + * inode_init_owner - Init uid,gid,mode for new inode according to posix standards + * @inode: New inode + * @dir: Directory inode + * @mode: mode of the new inode + */ +void inode_init_owner(struct inode *inode, const struct inode *dir, + umode_t mode) +{ + inode->i_uid = current_fsuid(); + if (dir && dir->i_mode & S_ISGID) { + inode->i_gid = dir->i_gid; + + /* Directories are special, and always inherit S_ISGID */ + if (S_ISDIR(mode)) + mode |= S_ISGID; + } else + inode->i_gid = current_fsgid(); + inode->i_mode = mode; +} +EXPORT_SYMBOL(inode_init_owner); + +/** + * inode_owner_or_capable - check current task permissions to inode + * @inode: inode being checked + * + * Return true if current either has CAP_FOWNER in a namespace with the + * inode owner uid mapped, or owns the file. + */ +bool inode_owner_or_capable(const struct inode *inode) +{ + struct user_namespace *ns; + + if (uid_eq(current_fsuid(), inode->i_uid)) + return true; + + ns = current_user_ns(); + if (kuid_has_mapping(ns, inode->i_uid) && ns_capable(ns, CAP_FOWNER)) + return true; + return false; +} +EXPORT_SYMBOL(inode_owner_or_capable); + +/* + * Direct i/o helper functions + */ +static void __inode_dio_wait(struct inode *inode) +{ + wait_queue_head_t *wq = bit_waitqueue(&inode->i_state, __I_DIO_WAKEUP); + DEFINE_WAIT_BIT(q, &inode->i_state, __I_DIO_WAKEUP); + + do { + prepare_to_wait(wq, &q.wq_entry, TASK_UNINTERRUPTIBLE); + if (atomic_read(&inode->i_dio_count)) + schedule(); + } while (atomic_read(&inode->i_dio_count)); + finish_wait(wq, &q.wq_entry); +} + +/** + * inode_dio_wait - wait for outstanding DIO requests to finish + * @inode: inode to wait for + * + * Waits for all pending direct I/O requests to finish so that we can + * proceed with a truncate or equivalent operation. + * + * Must be called under a lock that serializes taking new references + * to i_dio_count, usually by inode->i_mutex. + */ +void inode_dio_wait(struct inode *inode) +{ + if (atomic_read(&inode->i_dio_count)) + __inode_dio_wait(inode); +} +EXPORT_SYMBOL(inode_dio_wait); + +/* + * inode_set_flags - atomically set some inode flags + * + * Note: the caller should be holding i_mutex, or else be sure that + * they have exclusive access to the inode structure (i.e., while the + * inode is being instantiated). The reason for the cmpxchg() loop + * --- which wouldn't be necessary if all code paths which modify + * i_flags actually followed this rule, is that there is at least one + * code path which doesn't today so we use cmpxchg() out of an abundance + * of caution. + * + * In the long run, i_mutex is overkill, and we should probably look + * at using the i_lock spinlock to protect i_flags, and then make sure + * it is so documented in include/linux/fs.h and that all code follows + * the locking convention!! + */ +void inode_set_flags(struct inode *inode, unsigned int flags, + unsigned int mask) +{ + WARN_ON_ONCE(flags & ~mask); + set_mask_bits(&inode->i_flags, mask, flags); +} +EXPORT_SYMBOL(inode_set_flags); + +void inode_nohighmem(struct inode *inode) +{ + mapping_set_gfp_mask(inode->i_mapping, GFP_USER); +} +EXPORT_SYMBOL(inode_nohighmem); + +/** + * timestamp_truncate - Truncate timespec to a granularity + * @t: Timespec + * @inode: inode being updated + * + * Truncate a timespec to the granularity supported by the fs + * containing the inode. Always rounds down. gran must + * not be 0 nor greater than a second (NSEC_PER_SEC, or 10^9 ns). + */ +struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode) +{ + struct super_block *sb = inode->i_sb; + unsigned int gran = sb->s_time_gran; + + t.tv_sec = clamp(t.tv_sec, sb->s_time_min, sb->s_time_max); + if (unlikely(t.tv_sec == sb->s_time_max || t.tv_sec == sb->s_time_min)) + t.tv_nsec = 0; + + /* Avoid division in the common cases 1 ns and 1 s. */ + if (gran == 1) + ; /* nothing */ + else if (gran == NSEC_PER_SEC) + t.tv_nsec = 0; + else if (gran > 1 && gran < NSEC_PER_SEC) + t.tv_nsec -= t.tv_nsec % gran; + else + WARN(1, "invalid file time granularity: %u", gran); + return t; +} +EXPORT_SYMBOL(timestamp_truncate); + +/** + * current_time - Return FS time + * @inode: inode. + * + * Return the current time truncated to the time granularity supported by + * the fs. + * + * Note that inode and inode->sb cannot be NULL. + * Otherwise, the function warns and returns time without truncation. + */ +struct timespec64 current_time(struct inode *inode) +{ + struct timespec64 now; + + ktime_get_coarse_real_ts64(&now); + + if (unlikely(!inode->i_sb)) { + WARN(1, "current_time() called with uninitialized super_block in the inode"); + return now; + } + + return timestamp_truncate(now, inode); +} +EXPORT_SYMBOL(current_time); + +/* + * Generic function to check FS_IOC_SETFLAGS values and reject any invalid + * configurations. + * + * Note: the caller should be holding i_mutex, or else be sure that they have + * exclusive access to the inode structure. + */ +int vfs_ioc_setflags_prepare(struct inode *inode, unsigned int oldflags, + unsigned int flags) +{ + /* + * The IMMUTABLE and APPEND_ONLY flags can only be changed by + * the relevant capability. + * + * This test looks nicer. Thanks to Pauline Middelink + */ + if ((flags ^ oldflags) & (FS_APPEND_FL | FS_IMMUTABLE_FL) && + !capable(CAP_LINUX_IMMUTABLE)) + return -EPERM; + + return fscrypt_prepare_setflags(inode, oldflags, flags); +} +EXPORT_SYMBOL(vfs_ioc_setflags_prepare); + +/* + * Generic function to check FS_IOC_FSSETXATTR values and reject any invalid + * configurations. + * + * Note: the caller should be holding i_mutex, or else be sure that they have + * exclusive access to the inode structure. + */ +int vfs_ioc_fssetxattr_check(struct inode *inode, const struct fsxattr *old_fa, + struct fsxattr *fa) +{ + /* + * Can't modify an immutable/append-only file unless we have + * appropriate permission. + */ + if ((old_fa->fsx_xflags ^ fa->fsx_xflags) & + (FS_XFLAG_IMMUTABLE | FS_XFLAG_APPEND) && + !capable(CAP_LINUX_IMMUTABLE)) + return -EPERM; + + /* + * Project Quota ID state is only allowed to change from within the init + * namespace. Enforce that restriction only if we are trying to change + * the quota ID state. Everything else is allowed in user namespaces. + */ + if (current_user_ns() != &init_user_ns) { + if (old_fa->fsx_projid != fa->fsx_projid) + return -EINVAL; + if ((old_fa->fsx_xflags ^ fa->fsx_xflags) & + FS_XFLAG_PROJINHERIT) + return -EINVAL; + } + + /* Check extent size hints. */ + if ((fa->fsx_xflags & FS_XFLAG_EXTSIZE) && !S_ISREG(inode->i_mode)) + return -EINVAL; + + if ((fa->fsx_xflags & FS_XFLAG_EXTSZINHERIT) && + !S_ISDIR(inode->i_mode)) + return -EINVAL; + + if ((fa->fsx_xflags & FS_XFLAG_COWEXTSIZE) && + !S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) + return -EINVAL; + + /* + * It is only valid to set the DAX flag on regular files and + * directories on filesystems. + */ + if ((fa->fsx_xflags & FS_XFLAG_DAX) && + !(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))) + return -EINVAL; + + /* Extent size hints of zero turn off the flags. */ + if (fa->fsx_extsize == 0) + fa->fsx_xflags &= ~(FS_XFLAG_EXTSIZE | FS_XFLAG_EXTSZINHERIT); + if (fa->fsx_cowextsize == 0) + fa->fsx_xflags &= ~FS_XFLAG_COWEXTSIZE; + + return 0; +} +EXPORT_SYMBOL(vfs_ioc_fssetxattr_check); + +/** + * inode_set_ctime_current - set the ctime to current_time + * @inode: inode + * + * Set the inode->i_ctime to the current value for the inode. Returns + * the current value that was assigned to i_ctime. + */ +struct timespec64 inode_set_ctime_current(struct inode *inode) +{ + struct timespec64 now = current_time(inode); + + inode_set_ctime(inode, now.tv_sec, now.tv_nsec); + return now; +} +EXPORT_SYMBOL(inode_set_ctime_current); + +/** + * in_group_or_capable - check whether caller is CAP_FSETID privileged + * @inode: inode to check + * @gid: the new/current gid of @inode + * + * Check wether @gid is in the caller's group list or if the caller is + * privileged with CAP_FSETID over @inode. This can be used to determine + * whether the setgid bit can be kept or must be dropped. + * + * Return: true if the caller is sufficiently privileged, false if not. + */ +bool in_group_or_capable(const struct inode *inode, kgid_t gid) +{ + if (in_group_p(gid)) + return true; + if (capable_wrt_inode_uidgid(inode, CAP_FSETID)) + return true; + return false; +} + +/** + * mode_strip_sgid - handle the sgid bit for non-directories + * @dir: parent directory inode + * @mode: mode of the file to be created in @dir + * + * If the @mode of the new file has both the S_ISGID and S_IXGRP bit + * raised and @dir has the S_ISGID bit raised ensure that the caller is + * either in the group of the parent directory or they have CAP_FSETID + * in their user namespace and are privileged over the parent directory. + * In all other cases, strip the S_ISGID bit from @mode. + * + * Return: the new mode to use for the file + */ +umode_t mode_strip_sgid(const struct inode *dir, umode_t mode) +{ + if ((mode & (S_ISGID | S_IXGRP)) != (S_ISGID | S_IXGRP)) + return mode; + if (S_ISDIR(mode) || !dir || !(dir->i_mode & S_ISGID)) + return mode; + if (in_group_or_capable(dir, dir->i_gid)) + return mode; + return mode & ~S_ISGID; +} +EXPORT_SYMBOL(mode_strip_sgid); |