From 3e037e5211252902a188a6a11aecd247409d0229 Mon Sep 17 00:00:00 2001 From: T Makphaibulchoke Date: Tue, 18 Mar 2014 19:19:41 -0400 Subject: fs/mbcache.c: change block and index hash chain to hlist_bl_node This patch changes each mb_cache's both block and index hash chains to use a hlist_bl_node, which contains a built-in lock. This is the first step in decoupling of locks serializing accesses to mb_cache global data and each mb_cache_entry local data. Signed-off-by: T. Makphaibulchoke Signed-off-by: "Theodore Ts'o" --- include/linux/mbcache.h | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) (limited to 'include/linux') diff --git a/include/linux/mbcache.h b/include/linux/mbcache.h index 5525d370701d..6a392e7a723a 100644 --- a/include/linux/mbcache.h +++ b/include/linux/mbcache.h @@ -3,19 +3,21 @@ (C) 2001 by Andreas Gruenbacher, */ - struct mb_cache_entry { struct list_head e_lru_list; struct mb_cache *e_cache; unsigned short e_used; unsigned short e_queued; + atomic_t e_refcnt; struct block_device *e_bdev; sector_t e_block; - struct list_head e_block_list; + struct hlist_bl_node e_block_list; struct { - struct list_head o_list; + struct hlist_bl_node o_list; unsigned int o_key; } e_index; + struct hlist_bl_head *e_block_hash_p; + struct hlist_bl_head *e_index_hash_p; }; struct mb_cache { @@ -25,8 +27,8 @@ struct mb_cache { int c_max_entries; int c_bucket_bits; struct kmem_cache *c_entry_cache; - struct list_head *c_block_hash; - struct list_head *c_index_hash; + struct hlist_bl_head *c_block_hash; + struct hlist_bl_head *c_index_hash; }; /* Functions on caches */ -- cgit v1.2.3-71-gd317 From 5f16f3225b06242a9ee876f07c1c9b6ed36a22b6 Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Mon, 24 Mar 2014 14:43:12 -0400 Subject: ext4: atomically set inode->i_flags in ext4_set_inode_flags() Use cmpxchg() to atomically set i_flags instead of clearing out the S_IMMUTABLE, S_APPEND, etc. flags and then setting them from the EXT4_IMMUTABLE_FL, EXT4_APPEND_FL flags, since this opens up a race where an immutable file has the immutable flag cleared for a brief window of time. Reported-by: John Sullivan Signed-off-by: "Theodore Ts'o" Cc: stable@kernel.org --- fs/ext4/inode.c | 14 ++++++++------ fs/inode.c | 31 +++++++++++++++++++++++++++++++ include/linux/fs.h | 3 +++ 3 files changed, 42 insertions(+), 6 deletions(-) (limited to 'include/linux') diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c index b5e182acf9b9..df067c3c6c93 100644 --- a/fs/ext4/inode.c +++ b/fs/ext4/inode.c @@ -3938,18 +3938,20 @@ int ext4_get_inode_loc(struct inode *inode, struct ext4_iloc *iloc) void ext4_set_inode_flags(struct inode *inode) { unsigned int flags = EXT4_I(inode)->i_flags; + unsigned int new_fl = 0; - inode->i_flags &= ~(S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC); if (flags & EXT4_SYNC_FL) - inode->i_flags |= S_SYNC; + new_fl |= S_SYNC; if (flags & EXT4_APPEND_FL) - inode->i_flags |= S_APPEND; + new_fl |= S_APPEND; if (flags & EXT4_IMMUTABLE_FL) - inode->i_flags |= S_IMMUTABLE; + new_fl |= S_IMMUTABLE; if (flags & EXT4_NOATIME_FL) - inode->i_flags |= S_NOATIME; + new_fl |= S_NOATIME; if (flags & EXT4_DIRSYNC_FL) - inode->i_flags |= S_DIRSYNC; + new_fl |= S_DIRSYNC; + inode_set_flags(inode, new_fl, + S_SYNC|S_APPEND|S_IMMUTABLE|S_NOATIME|S_DIRSYNC); } /* Propagate flags from i_flags to EXT4_I(inode)->i_flags */ diff --git a/fs/inode.c b/fs/inode.c index 4bcdad3c9361..26f95ceb6250 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -1899,3 +1899,34 @@ void inode_dio_done(struct inode *inode) wake_up_bit(&inode->i_state, __I_DIO_WAKEUP); } EXPORT_SYMBOL(inode_dio_done); + +/* + * 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 --- for example, + * __generic_file_aio_write() calls file_remove_suid() without holding + * i_mutex --- 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) +{ + unsigned int old_flags, new_flags; + + WARN_ON_ONCE(flags & ~mask); + do { + old_flags = ACCESS_ONCE(inode->i_flags); + new_flags = (old_flags & ~mask) | flags; + } while (unlikely(cmpxchg(&inode->i_flags, old_flags, + new_flags) != old_flags)); +} +EXPORT_SYMBOL(inode_set_flags); diff --git a/include/linux/fs.h b/include/linux/fs.h index 60829565e552..5d1f6fa8daed 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2556,6 +2556,9 @@ static inline ssize_t blockdev_direct_IO(int rw, struct kiocb *iocb, void inode_dio_wait(struct inode *inode); void inode_dio_done(struct inode *inode); +extern void inode_set_flags(struct inode *inode, unsigned int flags, + unsigned int mask); + extern const struct file_operations generic_ro_fops; #define special_file(m) (S_ISCHR(m)||S_ISBLK(m)||S_ISFIFO(m)||S_ISSOCK(m)) -- cgit v1.2.3-71-gd317