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Date: Wed, 5 Jan 2011 11:26:05 +0200
From: Amir Goldstein <amir73il@...il.com>
To: "Theodore Ts'o" <tytso@....edu>
Cc: Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH 6/6] ext4: Dynamically allocate the jbd2_inode in
ext4_inode_info as necessary
On Wed, Jan 5, 2011 at 3:01 AM, Theodore Ts'o <tytso@....edu> wrote:
> Replace the jbd2_inode structure (which is 48 bytes) with a pointer
> and only allocate the jbd2_inode when it is needed --- that is, when
> the file system has a journal present and the inode has been opened
> for writing. This allows us to further slim down the ext4_inode_info
> structure.
>
> Signed-off-by: "Theodore Ts'o" <tytso@....edu>
> ---
> fs/ext4/ext4.h | 2 +-
> fs/ext4/ext4_jbd2.h | 2 +-
> fs/ext4/file.c | 19 +++++++++++++++++++
> fs/ext4/inode.c | 15 +++++++++++----
> fs/ext4/super.c | 16 +++++++---------
> fs/jbd2/journal.c | 20 +++++++++++++-------
> include/linux/jbd2.h | 20 ++++++++++++++++++--
> 7 files changed, 70 insertions(+), 24 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 8a2603d..50f35e8 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -811,7 +811,7 @@ struct ext4_inode_info {
> */
> struct rw_semaphore i_data_sem;
> struct inode vfs_inode;
> - struct jbd2_inode jinode;
> + struct jbd2_inode *jinode;
>
> struct ext4_ext_cache i_cached_extent;
> /*
> diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
> index b0bd792..d8b992e 100644
> --- a/fs/ext4/ext4_jbd2.h
> +++ b/fs/ext4/ext4_jbd2.h
> @@ -253,7 +253,7 @@ static inline int ext4_journal_force_commit(journal_t *journal)
> static inline int ext4_jbd2_file_inode(handle_t *handle, struct inode *inode)
> {
> if (ext4_handle_valid(handle))
> - return jbd2_journal_file_inode(handle, &EXT4_I(inode)->jinode);
> + return jbd2_journal_file_inode(handle, EXT4_I(inode)->jinode);
> return 0;
> }
>
> diff --git a/fs/ext4/file.c b/fs/ext4/file.c
> index 5a5c55d..45a656f 100644
> --- a/fs/ext4/file.c
> +++ b/fs/ext4/file.c
> @@ -104,6 +104,7 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
> {
> struct super_block *sb = inode->i_sb;
> struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
> + struct ext4_inode_info *ei = EXT4_I(inode);
> struct vfsmount *mnt = filp->f_path.mnt;
> struct path path;
> char buf[64], *cp;
> @@ -127,6 +128,24 @@ static int ext4_file_open(struct inode * inode, struct file * filp)
> ext4_mark_super_dirty(sb);
> }
> }
> + /*
> + * Set up the jbd2_inode if we are opening the inode for
> + * writing and the journal is present
> + */
> + if (sbi->s_journal && !ei->jinode && (filp->f_mode & FMODE_WRITE)) {
> + struct jbd2_inode *jinode = jbd2_alloc_inode(GFP_KERNEL);
> +
> + spin_lock(&inode->i_lock);
> + if (!ei->jinode) {
> + if (!jinode) {
> + spin_unlock(&inode->i_lock);
> + return -ENOMEM;
> + }
> + ei->jinode = jinode;
> + jbd2_journal_init_jbd_inode(ei->jinode, inode);
jinode = NULL;
> + }
> + spin_unlock(&inode->i_lock);
if (jinode)
// ei->jinode was allocated after first test - can it happen?
// if not, then 2nd test under spinlock is not needed
jbd2_free_inode(jinode);
> + }
> return dquot_file_open(inode, filp);
> }
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 2d60028..de3f2e3 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -55,10 +55,17 @@ static inline int ext4_begin_ordered_truncate(struct inode *inode,
> loff_t new_size)
> {
> trace_ext4_begin_ordered_truncate(inode, new_size);
> - return jbd2_journal_begin_ordered_truncate(
> - EXT4_SB(inode->i_sb)->s_journal,
> - &EXT4_I(inode)->jinode,
> - new_size);
> + /*
> + * If jinode is zero, then we never opened the file for
> + * writing, so there's no need to call
> + * jbd2_journal_begin_ordered_truncate() since there's no
> + * outstanding writes we need to flush.
> + */
> + if (!EXT4_I(inode)->jinode)
> + return 0;
> + return jbd2_journal_begin_ordered_truncate(EXT4_JOURNAL(inode),
> + EXT4_I(inode)->jinode,
> + new_size);
> }
>
> static void ext4_invalidatepage(struct page *page, unsigned long offset);
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index f5960d6..7f99ac7 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -818,12 +818,6 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
> memset(&ei->i_cached_extent, 0, sizeof(struct ext4_ext_cache));
> INIT_LIST_HEAD(&ei->i_prealloc_list);
> spin_lock_init(&ei->i_prealloc_lock);
> - /*
> - * Note: We can be called before EXT4_SB(sb)->s_journal is set,
> - * therefore it can be null here. Don't check it, just initialize
> - * jinode.
> - */
> - jbd2_journal_init_jbd_inode(&ei->jinode, &ei->vfs_inode);
> ei->i_reserved_data_blocks = 0;
> ei->i_reserved_meta_blocks = 0;
> ei->i_allocated_meta_blocks = 0;
> @@ -832,6 +826,7 @@ static struct inode *ext4_alloc_inode(struct super_block *sb)
> #ifdef CONFIG_QUOTA
> ei->i_reserved_quota = 0;
> #endif
> + ei->jinode = 0;
> INIT_LIST_HEAD(&ei->i_completed_io_list);
> spin_lock_init(&ei->i_completed_io_lock);
> ei->cur_aio_dio = NULL;
> @@ -900,9 +895,12 @@ void ext4_clear_inode(struct inode *inode)
> end_writeback(inode);
> dquot_drop(inode);
> ext4_discard_preallocations(inode);
> - if (EXT4_JOURNAL(inode))
> - jbd2_journal_release_jbd_inode(EXT4_SB(inode->i_sb)->s_journal,
> - &EXT4_I(inode)->jinode);
> + if (EXT4_JOURNAL(inode) && EXT4_I(inode)->jinode) {
> + jbd2_journal_release_jbd_inode(EXT4_JOURNAL(inode),
> + EXT4_I(inode)->jinode);
> + jbd2_free_inode(EXT4_I(inode)->jinode);
> + EXT4_I(inode)->jinode = 0;
> + }
> }
>
> static inline void ext4_show_quota_options(struct seq_file *seq,
> diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
> index 2447bd8..9e46869 100644
> --- a/fs/jbd2/journal.c
> +++ b/fs/jbd2/journal.c
> @@ -94,6 +94,7 @@ EXPORT_SYMBOL(jbd2_journal_file_inode);
> EXPORT_SYMBOL(jbd2_journal_init_jbd_inode);
> EXPORT_SYMBOL(jbd2_journal_release_jbd_inode);
> EXPORT_SYMBOL(jbd2_journal_begin_ordered_truncate);
> +EXPORT_SYMBOL(jbd2_inode_cache);
>
> static int journal_convert_superblock_v1(journal_t *, journal_superblock_t *);
> static void __journal_abort_soft (journal_t *journal, int errno);
> @@ -2286,17 +2287,19 @@ static void __exit jbd2_remove_jbd_stats_proc_entry(void)
>
> #endif
>
> -struct kmem_cache *jbd2_handle_cache;
> +struct kmem_cache *jbd2_handle_cache, *jbd2_inode_cache;
>
> static int __init journal_init_handle_cache(void)
> {
> - jbd2_handle_cache = kmem_cache_create("jbd2_journal_handle",
> - sizeof(handle_t),
> - 0, /* offset */
> - SLAB_TEMPORARY, /* flags */
> - NULL); /* ctor */
> + jbd2_handle_cache = KMEM_CACHE(jbd2_journal_handle, SLAB_TEMPORARY);
> if (jbd2_handle_cache == NULL) {
> - printk(KERN_EMERG "JBD: failed to create handle cache\n");
> + printk(KERN_EMERG "JBD2: failed to create handle cache\n");
> + return -ENOMEM;
> + }
> + jbd2_inode_cache = KMEM_CACHE(jbd2_inode, 0);
> + if (jbd2_inode_cache == NULL) {
> + printk(KERN_EMERG "JBD2: failed to create inode cache\n");
> + kmem_cache_destroy(jbd2_handle_cache);
> return -ENOMEM;
> }
> return 0;
> @@ -2306,6 +2309,9 @@ static void jbd2_journal_destroy_handle_cache(void)
> {
> if (jbd2_handle_cache)
> kmem_cache_destroy(jbd2_handle_cache);
> + if (jbd2_inode_cache)
> + kmem_cache_destroy(jbd2_inode_cache);
> +
> }
>
> /*
> diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
> index 2ae86aa..27e79c2 100644
> --- a/include/linux/jbd2.h
> +++ b/include/linux/jbd2.h
> @@ -94,7 +94,7 @@ extern void jbd2_free(void *ptr, size_t size);
> *
> * This is an opaque datatype.
> **/
> -typedef struct handle_s handle_t; /* Atomic operation type */
> +typedef struct jbd2_journal_handle handle_t; /* Atomic operation type */
>
>
> /**
> @@ -416,7 +416,7 @@ struct jbd2_revoke_table_s;
> * in so it can be fixed later.
> */
>
> -struct handle_s
> +struct jbd2_journal_handle
> {
> /* Which compound transaction is this update a part of? */
> transaction_t *h_transaction;
> @@ -1158,6 +1158,22 @@ static inline void jbd2_free_handle(handle_t *handle)
> kmem_cache_free(jbd2_handle_cache, handle);
> }
>
> +/*
> + * jbd2_inode management (optional, for those file systems that want to use
> + * dynamically allocated jbd2_inode structures)
> + */
> +extern struct kmem_cache *jbd2_inode_cache;
> +
> +static inline struct jbd2_inode *jbd2_alloc_inode(gfp_t gfp_flags)
> +{
> + return kmem_cache_alloc(jbd2_inode_cache, gfp_flags);
> +}
> +
> +static inline void jbd2_free_inode(struct jbd2_inode *jinode)
> +{
> + kmem_cache_free(jbd2_inode_cache, jinode);
> +}
> +
> /* Primary revoke support */
> #define JOURNAL_REVOKE_DEFAULT_HASH 256
> extern int jbd2_journal_init_revoke(journal_t *, int);
> --
> 1.7.3.1
>
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