diff options
author | Miklos Szeredi <mszeredi@suse.cz> | 2011-11-21 11:11:32 (GMT) |
---|---|---|
committer | Al Viro <viro@zeniv.linux.org.uk> | 2012-01-07 04:20:12 (GMT) |
commit | 7ada4db88634429f4da690ad1c4eb73c93085f0c (patch) | |
tree | ed1228f0bfa9d0050d746933595004d7c6e940f9 /fs | |
parent | 4ed5e82fe77f4147cf386327c9a63a2dd7eff518 (diff) | |
download | linux-fsl-qoriq-7ada4db88634429f4da690ad1c4eb73c93085f0c.tar.xz |
vfs: count unlinked inodes
Add a new counter to the superblock that keeps track of unlinked but
not yet deleted inodes.
Do not WARN_ON if set_nlink is called with zero count, just do a
ratelimited printk. This happens on xfs and probably other
filesystems after an unclean shutdown when the filesystem reads inodes
which already have zero i_nlink. Reported by Christoph Hellwig.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Toshiyuki Okajima <toshi.okajima@jp.fujitsu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/inode.c | 85 |
1 files changed, 85 insertions, 0 deletions
@@ -26,6 +26,7 @@ #include <linux/ima.h> #include <linux/cred.h> #include <linux/buffer_head.h> /* for inode_has_buffers */ +#include <linux/ratelimit.h> #include "internal.h" /* @@ -242,6 +243,11 @@ void __destroy_inode(struct inode *inode) BUG_ON(inode_has_buffers(inode)); security_inode_free(inode); fsnotify_inode_delete(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 && inode->i_acl != ACL_NOT_CACHED) posix_acl_release(inode->i_acl); @@ -268,6 +274,85 @@ static void destroy_inode(struct inode *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) { + printk_ratelimited(KERN_INFO + "set_nlink() clearing i_nlink on %s inode %li\n", + inode->i_sb->s_type->name, inode->i_ino); + 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 (WARN_ON(inode->i_nlink == 0)) + atomic_long_dec(&inode->i_sb->s_remove_count); + + inode->__i_nlink++; +} +EXPORT_SYMBOL(inc_nlink); + void address_space_init_once(struct address_space *mapping) { memset(mapping, 0, sizeof(*mapping)); |