diff options
| author | Tejun Heo <tj@kernel.org> | 2015-05-28 20:50:55 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2015-06-02 16:40:20 +0200 |
| commit | aaa2cacf8184e2a92accb8e443b1608d65f9a13f (patch) | |
| tree | 5635bab2ab977fd2e5de67d37555071557dee2a1 /fs/fs-writeback.c | |
| parent | writeback: use unlocked_inode_to_wb transaction in inode_congested() (diff) | |
| download | linux-aaa2cacf8184e2a92accb8e443b1608d65f9a13f.tar.xz linux-aaa2cacf8184e2a92accb8e443b1608d65f9a13f.zip | |
writeback: add lockdep annotation to inode_to_wb()
With the previous three patches, all operations which acquire wb from
inode are either under one of inode->i_lock, mapping->tree_lock or
wb->list_lock or protected by unlocked_inode_to_wb transaction. This
will be depended upon by foreign inode wb switching.
This patch adds lockdep assertion to inode_to_wb() so that usages
outside the above list locks can be caught easily. There are three
exceptions.
* locked_inode_to_wb_and_lock_list() is holding wb->list_lock but the
wb may not be the inode's. Ensuring that is the function's role
after all. Updated to deref inode->i_wb directly.
* inode_wb_stat_unlocked_begin() is usually protected by combination
of !I_WB_SWITCH and rcu_read_lock(). Updated to deref inode->i_wb
directly.
* inode_congested() wants to test whether inode->i_wb is set before
starting the transaction. Added inode_to_wb_is_valid() which tests
inode->i_wb directly.
v5: might_lock() removed. It annotates that the lock is grabbed w/
irq enabled which isn't the case and triggering lockdep warning
spuriously.
v4: might_lock() added to unlocked_inode_to_wb_begin().
v3: inode_congested() conversion added.
v2: locked_inode_to_wb_and_lock_list() was missing in the first
version.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jan Kara <jack@suse.cz>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Greg Thelen <gthelen@google.com>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'fs/fs-writeback.c')
| -rw-r--r-- | fs/fs-writeback.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 25458fa4753d..6b99deeb9de0 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -285,7 +285,8 @@ locked_inode_to_wb_and_lock_list(struct inode *inode) spin_lock(&wb->list_lock); wb_put(wb); /* not gonna deref it anymore */ - if (likely(wb == inode_to_wb(inode))) + /* i_wb may have changed inbetween, can't use inode_to_wb() */ + if (likely(wb == inode->i_wb)) return wb; /* @inode already has ref */ spin_unlock(&wb->list_lock); @@ -622,7 +623,7 @@ int inode_congested(struct inode *inode, int cong_bits) * Once set, ->i_wb never becomes NULL while the inode is alive. * Start transaction iff ->i_wb is visible. */ - if (inode && inode_to_wb(inode)) { + if (inode && inode_to_wb_is_valid(inode)) { struct bdi_writeback *wb; bool locked, congested; |