From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta7.messagelabs.com (mail6.bemta7.messagelabs.com [216.82.255.55]) by kanga.kvack.org (Postfix) with ESMTP id 96EE26B00E8 for ; Tue, 14 Jun 2011 06:57:57 -0400 (EDT) Received: from wpaz29.hot.corp.google.com (wpaz29.hot.corp.google.com [172.24.198.93]) by smtp-out.google.com with ESMTP id p5EAvhEq017262 for ; Tue, 14 Jun 2011 03:57:43 -0700 Received: from pvc21 (pvc21.prod.google.com [10.241.209.149]) by wpaz29.hot.corp.google.com with ESMTP id p5EAvfX5016182 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Tue, 14 Jun 2011 03:57:42 -0700 Received: by pvc21 with SMTP id 21so3732952pvc.39 for ; Tue, 14 Jun 2011 03:57:41 -0700 (PDT) Date: Tue, 14 Jun 2011 03:57:30 -0700 (PDT) From: Hugh Dickins Subject: [PATCH 11/12] tmpfs: use kmemdup for short symlinks In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org But we've not yet removed the old swp_entry_t i_direct[16] from shmem_inode_info. That's because it was still being shared with the inline symlink. Remove it now (saving 64 or 128 bytes from shmem inode size), and use kmemdup() for short symlinks, say, those up to 128 bytes. I wonder why mpol_free_shared_policy() is done in shmem_destroy_inode() rather than shmem_evict_inode(), where we usually do such freeing? I guess it doesn't matter, and I'm not into NUMA mpol testing right now. Signed-off-by: Hugh Dickins --- include/linux/shmem_fs.h | 11 +++-------- mm/shmem.c | 31 ++++++++++++++++++------------- 2 files changed, 21 insertions(+), 21 deletions(-) --- linux.orig/include/linux/shmem_fs.h 2011-06-14 00:45:20.625161293 -0700 +++ linux/include/linux/shmem_fs.h 2011-06-14 00:54:49.667983016 -0700 @@ -8,20 +8,15 @@ /* inode in-kernel data */ -#define SHMEM_NR_DIRECT 16 - -#define SHMEM_SYMLINK_INLINE_LEN (SHMEM_NR_DIRECT * sizeof(swp_entry_t)) - struct shmem_inode_info { spinlock_t lock; unsigned long flags; unsigned long alloced; /* data pages alloced to file */ - unsigned long swapped; /* subtotal assigned to swap */ - struct shared_policy policy; /* NUMA memory alloc policy */ union { - swp_entry_t i_direct[SHMEM_NR_DIRECT]; /* first blocks */ - char inline_symlink[SHMEM_SYMLINK_INLINE_LEN]; + unsigned long swapped; /* subtotal assigned to swap */ + char *symlink; /* unswappable short symlink */ }; + struct shared_policy policy; /* NUMA memory alloc policy */ struct list_head swaplist; /* chain of maybes on swap */ struct list_head xattr_list; /* list of shmem_xattr */ struct inode vfs_inode; --- linux.orig/mm/shmem.c 2011-06-14 00:54:36.499917716 -0700 +++ linux/mm/shmem.c 2011-06-14 00:54:49.667983016 -0700 @@ -73,6 +73,9 @@ static struct vfsmount *shm_mnt; /* Pretend that each entry is of this size in directory's i_size */ #define BOGO_DIRENT_SIZE 20 +/* Symlink up to this size is kmalloc'ed instead of using a swappable page */ +#define SHORT_SYMLINK_LEN 128 + struct shmem_xattr { struct list_head list; /* anchored by shmem_inode_info->xattr_list */ char *name; /* xattr name */ @@ -585,7 +588,8 @@ static void shmem_evict_inode(struct ino list_del_init(&info->swaplist); mutex_unlock(&shmem_swaplist_mutex); } - } + } else + kfree(info->symlink); list_for_each_entry_safe(xattr, nxattr, &info->xattr_list, list) { kfree(xattr->name); @@ -1173,7 +1177,7 @@ static struct inode *shmem_get_inode(str #ifdef CONFIG_TMPFS static const struct inode_operations shmem_symlink_inode_operations; -static const struct inode_operations shmem_symlink_inline_operations; +static const struct inode_operations shmem_short_symlink_operations; static int shmem_write_begin(struct file *file, struct address_space *mapping, @@ -1638,10 +1642,13 @@ static int shmem_symlink(struct inode *d 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; + if (len <= SHORT_SYMLINK_LEN) { + info->symlink = kmemdup(symname, len, GFP_KERNEL); + if (!info->symlink) { + iput(inode); + return -ENOMEM; + } + inode->i_op = &shmem_short_symlink_operations; } else { error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); if (error) { @@ -1664,9 +1671,9 @@ static int shmem_symlink(struct inode *d return 0; } -static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) +static void *shmem_follow_short_symlink(struct dentry *dentry, struct nameidata *nd) { - nd_set_link(nd, SHMEM_I(dentry->d_inode)->inline_symlink); + nd_set_link(nd, SHMEM_I(dentry->d_inode)->symlink); return NULL; } @@ -1914,9 +1921,9 @@ static ssize_t shmem_listxattr(struct de } #endif /* CONFIG_TMPFS_XATTR */ -static const struct inode_operations shmem_symlink_inline_operations = { +static const struct inode_operations shmem_short_symlink_operations = { .readlink = generic_readlink, - .follow_link = shmem_follow_link_inline, + .follow_link = shmem_follow_short_symlink, #ifdef CONFIG_TMPFS_XATTR .setxattr = shmem_setxattr, .getxattr = shmem_getxattr, @@ -2259,10 +2266,8 @@ static void shmem_destroy_callback(struc 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 */ + if ((inode->i_mode & S_IFMT) == S_IFREG) mpol_free_shared_policy(&SHMEM_I(inode)->policy); - } call_rcu(&inode->i_rcu, shmem_destroy_callback); } -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. 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