+++ /dev/null
-/*
- * fs/logfs/inode.c - inode handling code
- *
- * As should be obvious for Linux kernel code, license is GPLv2
- *
- * Copyright (c) 2005-2008 Joern Engel <joern@logfs.org>
- */
-#include "logfs.h"
-#include <linux/slab.h>
-#include <linux/writeback.h>
-#include <linux/backing-dev.h>
-
-/*
- * How soon to reuse old inode numbers? LogFS doesn't store deleted inodes
- * on the medium. It therefore also lacks a method to store the previous
- * generation number for deleted inodes. Instead a single generation number
- * is stored which will be used for new inodes. Being just a 32bit counter,
- * this can obvious wrap relatively quickly. So we only reuse inodes if we
- * know that a fair number of inodes can be created before we have to increment
- * the generation again - effectively adding some bits to the counter.
- * But being too aggressive here means we keep a very large and very sparse
- * inode file, wasting space on indirect blocks.
- * So what is a good value? Beats me. 64k seems moderately bad on both
- * fronts, so let's use that for now...
- *
- * NFS sucks, as everyone already knows.
- */
-#define INOS_PER_WRAP (0x10000)
-
-/*
- * Logfs' requirement to read inodes for garbage collection makes life a bit
- * harder. GC may have to read inodes that are in I_FREEING state, when they
- * are being written out - and waiting for GC to make progress, naturally.
- *
- * So we cannot just call iget() or some variant of it, but first have to check
- * whether the inode in question might be in I_FREEING state. Therefore we
- * maintain our own per-sb list of "almost deleted" inodes and check against
- * that list first. Normally this should be at most 1-2 entries long.
- *
- * Also, inodes have logfs-specific reference counting on top of what the vfs
- * does. When .destroy_inode is called, normally the reference count will drop
- * to zero and the inode gets deleted. But if GC accessed the inode, its
- * refcount will remain nonzero and final deletion will have to wait.
- *
- * As a result we have two sets of functions to get/put inodes:
- * logfs_safe_iget/logfs_safe_iput - safe to call from GC context
- * logfs_iget/iput - normal version
- */
-static struct kmem_cache *logfs_inode_cache;
-
-static DEFINE_SPINLOCK(logfs_inode_lock);
-
-static void logfs_inode_setops(struct inode *inode)
-{
- switch (inode->i_mode & S_IFMT) {
- case S_IFDIR:
- inode->i_op = &logfs_dir_iops;
- inode->i_fop = &logfs_dir_fops;
- inode->i_mapping->a_ops = &logfs_reg_aops;
- break;
- case S_IFREG:
- inode->i_op = &logfs_reg_iops;
- inode->i_fop = &logfs_reg_fops;
- inode->i_mapping->a_ops = &logfs_reg_aops;
- break;
- case S_IFLNK:
- inode->i_op = &page_symlink_inode_operations;
- inode_nohighmem(inode);
- inode->i_mapping->a_ops = &logfs_reg_aops;
- break;
- case S_IFSOCK: /* fall through */
- case S_IFBLK: /* fall through */
- case S_IFCHR: /* fall through */
- case S_IFIFO:
- init_special_inode(inode, inode->i_mode, inode->i_rdev);
- break;
- default:
- BUG();
- }
-}
-
-static struct inode *__logfs_iget(struct super_block *sb, ino_t ino)
-{
- struct inode *inode = iget_locked(sb, ino);
- int err;
-
- if (!inode)
- return ERR_PTR(-ENOMEM);
- if (!(inode->i_state & I_NEW))
- return inode;
-
- err = logfs_read_inode(inode);
- if (err || inode->i_nlink == 0) {
- /* inode->i_nlink == 0 can be true when called from
- * block validator */
- /* set i_nlink to 0 to prevent caching */
- clear_nlink(inode);
- logfs_inode(inode)->li_flags |= LOGFS_IF_ZOMBIE;
- iget_failed(inode);
- if (!err)
- err = -ENOENT;
- return ERR_PTR(err);
- }
-
- logfs_inode_setops(inode);
- unlock_new_inode(inode);
- return inode;
-}
-
-struct inode *logfs_iget(struct super_block *sb, ino_t ino)
-{
- BUG_ON(ino == LOGFS_INO_MASTER);
- BUG_ON(ino == LOGFS_INO_SEGFILE);
- return __logfs_iget(sb, ino);
-}
-
-/*
- * is_cached is set to 1 if we hand out a cached inode, 0 otherwise.
- * this allows logfs_iput to do the right thing later
- */
-struct inode *logfs_safe_iget(struct super_block *sb, ino_t ino, int *is_cached)
-{
- struct logfs_super *super = logfs_super(sb);
- struct logfs_inode *li;
-
- if (ino == LOGFS_INO_MASTER)
- return super->s_master_inode;
- if (ino == LOGFS_INO_SEGFILE)
- return super->s_segfile_inode;
-
- spin_lock(&logfs_inode_lock);
- list_for_each_entry(li, &super->s_freeing_list, li_freeing_list)
- if (li->vfs_inode.i_ino == ino) {
- li->li_refcount++;
- spin_unlock(&logfs_inode_lock);
- *is_cached = 1;
- return &li->vfs_inode;
- }
- spin_unlock(&logfs_inode_lock);
-
- *is_cached = 0;
- return __logfs_iget(sb, ino);
-}
-
-static void logfs_i_callback(struct rcu_head *head)
-{
- struct inode *inode = container_of(head, struct inode, i_rcu);
- kmem_cache_free(logfs_inode_cache, logfs_inode(inode));
-}
-
-static void __logfs_destroy_inode(struct inode *inode)
-{
- struct logfs_inode *li = logfs_inode(inode);
-
- BUG_ON(li->li_block);
- list_del(&li->li_freeing_list);
- call_rcu(&inode->i_rcu, logfs_i_callback);
-}
-
-static void __logfs_destroy_meta_inode(struct inode *inode)
-{
- struct logfs_inode *li = logfs_inode(inode);
- BUG_ON(li->li_block);
- call_rcu(&inode->i_rcu, logfs_i_callback);
-}
-
-static void logfs_destroy_inode(struct inode *inode)
-{
- struct logfs_inode *li = logfs_inode(inode);
-
- if (inode->i_ino < LOGFS_RESERVED_INOS) {
- /*
- * The reserved inodes are never destroyed unless we are in
- * unmont path.
- */
- __logfs_destroy_meta_inode(inode);
- return;
- }
-
- BUG_ON(list_empty(&li->li_freeing_list));
- spin_lock(&logfs_inode_lock);
- li->li_refcount--;
- if (li->li_refcount == 0)
- __logfs_destroy_inode(inode);
- spin_unlock(&logfs_inode_lock);
-}
-
-void logfs_safe_iput(struct inode *inode, int is_cached)
-{
- if (inode->i_ino == LOGFS_INO_MASTER)
- return;
- if (inode->i_ino == LOGFS_INO_SEGFILE)
- return;
-
- if (is_cached) {
- logfs_destroy_inode(inode);
- return;
- }
-
- iput(inode);
-}
-
-static void logfs_init_inode(struct super_block *sb, struct inode *inode)
-{
- struct logfs_inode *li = logfs_inode(inode);
- int i;
-
- li->li_flags = 0;
- li->li_height = 0;
- li->li_used_bytes = 0;
- li->li_block = NULL;
- i_uid_write(inode, 0);
- i_gid_write(inode, 0);
- inode->i_size = 0;
- inode->i_blocks = 0;
- inode->i_ctime = current_time(inode);
- inode->i_mtime = current_time(inode);
- li->li_refcount = 1;
- INIT_LIST_HEAD(&li->li_freeing_list);
-
- for (i = 0; i < LOGFS_EMBEDDED_FIELDS; i++)
- li->li_data[i] = 0;
-
- return;
-}
-
-static struct inode *logfs_alloc_inode(struct super_block *sb)
-{
- struct logfs_inode *li;
-
- li = kmem_cache_alloc(logfs_inode_cache, GFP_NOFS);
- if (!li)
- return NULL;
- logfs_init_inode(sb, &li->vfs_inode);
- return &li->vfs_inode;
-}
-
-/*
- * In logfs inodes are written to an inode file. The inode file, like any
- * other file, is managed with a inode. The inode file's inode, aka master
- * inode, requires special handling in several respects. First, it cannot be
- * written to the inode file, so it is stored in the journal instead.
- *
- * Secondly, this inode cannot be written back and destroyed before all other
- * inodes have been written. The ordering is important. Linux' VFS is happily
- * unaware of the ordering constraint and would ordinarily destroy the master
- * inode at umount time while other inodes are still in use and dirty. Not
- * good.
- *
- * So logfs makes sure the master inode is not written until all other inodes
- * have been destroyed. Sadly, this method has another side-effect. The VFS
- * will notice one remaining inode and print a frightening warning message.
- * Worse, it is impossible to judge whether such a warning was caused by the
- * master inode or any other inodes have leaked as well.
- *
- * Our attempt of solving this is with logfs_new_meta_inode() below. Its
- * purpose is to create a new inode that will not trigger the warning if such
- * an inode is still in use. An ugly hack, no doubt. Suggections for
- * improvement are welcome.
- *
- * AV: that's what ->put_super() is for...
- */
-struct inode *logfs_new_meta_inode(struct super_block *sb, u64 ino)
-{
- struct inode *inode;
-
- inode = new_inode(sb);
- if (!inode)
- return ERR_PTR(-ENOMEM);
-
- inode->i_mode = S_IFREG;
- inode->i_ino = ino;
- inode->i_data.a_ops = &logfs_reg_aops;
- mapping_set_gfp_mask(&inode->i_data, GFP_NOFS);
-
- return inode;
-}
-
-struct inode *logfs_read_meta_inode(struct super_block *sb, u64 ino)
-{
- struct inode *inode;
- int err;
-
- inode = logfs_new_meta_inode(sb, ino);
- if (IS_ERR(inode))
- return inode;
-
- err = logfs_read_inode(inode);
- if (err) {
- iput(inode);
- return ERR_PTR(err);
- }
- logfs_inode_setops(inode);
- return inode;
-}
-
-static int logfs_write_inode(struct inode *inode, struct writeback_control *wbc)
-{
- int ret;
- long flags = WF_LOCK;
-
- /* Can only happen if creat() failed. Safe to skip. */
- if (logfs_inode(inode)->li_flags & LOGFS_IF_STILLBORN)
- return 0;
-
- ret = __logfs_write_inode(inode, NULL, flags);
- LOGFS_BUG_ON(ret, inode->i_sb);
- return ret;
-}
-
-/* called with inode->i_lock held */
-static int logfs_drop_inode(struct inode *inode)
-{
- struct logfs_super *super = logfs_super(inode->i_sb);
- struct logfs_inode *li = logfs_inode(inode);
-
- spin_lock(&logfs_inode_lock);
- list_move(&li->li_freeing_list, &super->s_freeing_list);
- spin_unlock(&logfs_inode_lock);
- return generic_drop_inode(inode);
-}
-
-static void logfs_set_ino_generation(struct super_block *sb,
- struct inode *inode)
-{
- struct logfs_super *super = logfs_super(sb);
- u64 ino;
-
- mutex_lock(&super->s_journal_mutex);
- ino = logfs_seek_hole(super->s_master_inode, super->s_last_ino + 1);
- super->s_last_ino = ino;
- super->s_inos_till_wrap--;
- if (super->s_inos_till_wrap < 0) {
- super->s_last_ino = LOGFS_RESERVED_INOS;
- super->s_generation++;
- super->s_inos_till_wrap = INOS_PER_WRAP;
- }
- inode->i_ino = ino;
- inode->i_generation = super->s_generation;
- mutex_unlock(&super->s_journal_mutex);
-}
-
-struct inode *logfs_new_inode(struct inode *dir, umode_t mode)
-{
- struct super_block *sb = dir->i_sb;
- struct inode *inode;
-
- inode = new_inode(sb);
- if (!inode)
- return ERR_PTR(-ENOMEM);
-
- logfs_init_inode(sb, inode);
-
- /* inherit parent flags */
- logfs_inode(inode)->li_flags |=
- logfs_inode(dir)->li_flags & LOGFS_FL_INHERITED;
-
- inode->i_mode = mode;
- logfs_set_ino_generation(sb, inode);
-
- inode_init_owner(inode, dir, mode);
- logfs_inode_setops(inode);
- insert_inode_hash(inode);
-
- return inode;
-}
-
-static void logfs_init_once(void *_li)
-{
- struct logfs_inode *li = _li;
- int i;
-
- li->li_flags = 0;
- li->li_used_bytes = 0;
- li->li_refcount = 1;
- for (i = 0; i < LOGFS_EMBEDDED_FIELDS; i++)
- li->li_data[i] = 0;
- inode_init_once(&li->vfs_inode);
-}
-
-static int logfs_sync_fs(struct super_block *sb, int wait)
-{
- logfs_get_wblocks(sb, NULL, WF_LOCK);
- logfs_write_anchor(sb);
- logfs_put_wblocks(sb, NULL, WF_LOCK);
- return 0;
-}
-
-static void logfs_put_super(struct super_block *sb)
-{
- struct logfs_super *super = logfs_super(sb);
- /* kill the meta-inodes */
- iput(super->s_segfile_inode);
- iput(super->s_master_inode);
- iput(super->s_mapping_inode);
-}
-
-const struct super_operations logfs_super_operations = {
- .alloc_inode = logfs_alloc_inode,
- .destroy_inode = logfs_destroy_inode,
- .evict_inode = logfs_evict_inode,
- .drop_inode = logfs_drop_inode,
- .put_super = logfs_put_super,
- .write_inode = logfs_write_inode,
- .statfs = logfs_statfs,
- .sync_fs = logfs_sync_fs,
-};
-
-int logfs_init_inode_cache(void)
-{
- logfs_inode_cache = kmem_cache_create("logfs_inode_cache",
- sizeof(struct logfs_inode), 0,
- SLAB_RECLAIM_ACCOUNT|SLAB_ACCOUNT,
- logfs_init_once);
- if (!logfs_inode_cache)
- return -ENOMEM;
- return 0;
-}
-
-void logfs_destroy_inode_cache(void)
-{
- /*
- * Make sure all delayed rcu free inodes are flushed before we
- * destroy cache.
- */
- rcu_barrier();
- kmem_cache_destroy(logfs_inode_cache);
-}
git.samba.org / sfrench / cifs-2.6.git / blobdiff