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authorLinus Torvalds <torvalds@linux-foundation.org>2019-01-26 12:42:41 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-01-26 12:42:41 -0800
commit6b8f9159166545e576b2bc8a0c984beaeae9cc05 (patch)
tree6be248cacde030276ad7da750e71a1401d87bd51 /fs
parentba606975938179b1e893e44e190d0001de8e5262 (diff)
parent8367de2c99a13d35960a51d6084631c883e93a4d (diff)
Merge tag 'for-linus-20190125' of git://git.kernel.dk/linux-block
Pull block fixes from Jens Axboe: "A collection of fixes for this release. This contains: - Silence sparse rightfully complaining about non-static wbt functions (Bart) - Fixes for the zoned comments/ioctl documentation (Damien) - direct-io fix that's been lingering for a while (Ernesto) - cgroup writeback fix (Tejun) - Set of NVMe patches for nvme-rdma/tcp (Sagi, Hannes, Raju) - Block recursion tracking fix (Ming) - Fix debugfs command flag naming for a few flags (Jianchao)" * tag 'for-linus-20190125' of git://git.kernel.dk/linux-block: block: Fix comment typo uapi: fix ioctl documentation blk-wbt: Declare local functions static blk-mq: fix the cmd_flag_name array nvme-multipath: drop optimization for static ANA group IDs nvmet-rdma: fix null dereference under heavy load nvme-rdma: rework queue maps handling nvme-tcp: fix timeout handler nvme-rdma: fix timeout handler writeback: synchronize sync(2) against cgroup writeback membership switches block: cover another queue enter recursion via BIO_QUEUE_ENTERED direct-io: allow direct writes to empty inodes
Diffstat (limited to 'fs')
-rw-r--r--fs/direct-io.c5
-rw-r--r--fs/fs-writeback.c40
2 files changed, 41 insertions, 4 deletions
diff --git a/fs/direct-io.c b/fs/direct-io.c
index dbc1a1f080ce..ec2fb6fe6d37 100644
--- a/fs/direct-io.c
+++ b/fs/direct-io.c
@@ -679,6 +679,7 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio,
unsigned long fs_count; /* Number of filesystem-sized blocks */
int create;
unsigned int i_blkbits = sdio->blkbits + sdio->blkfactor;
+ loff_t i_size;
/*
* If there was a memory error and we've overwritten all the
@@ -708,8 +709,8 @@ static int get_more_blocks(struct dio *dio, struct dio_submit *sdio,
*/
create = dio->op == REQ_OP_WRITE;
if (dio->flags & DIO_SKIP_HOLES) {
- if (fs_startblk <= ((i_size_read(dio->inode) - 1) >>
- i_blkbits))
+ i_size = i_size_read(dio->inode);
+ if (i_size && fs_startblk <= (i_size - 1) >> i_blkbits)
create = 0;
}
diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index b40168fcc94a..36855c1f8daf 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -331,11 +331,22 @@ struct inode_switch_wbs_context {
struct work_struct work;
};
+static void bdi_down_write_wb_switch_rwsem(struct backing_dev_info *bdi)
+{
+ down_write(&bdi->wb_switch_rwsem);
+}
+
+static void bdi_up_write_wb_switch_rwsem(struct backing_dev_info *bdi)
+{
+ up_write(&bdi->wb_switch_rwsem);
+}
+
static void inode_switch_wbs_work_fn(struct work_struct *work)
{
struct inode_switch_wbs_context *isw =
container_of(work, struct inode_switch_wbs_context, work);
struct inode *inode = isw->inode;
+ struct backing_dev_info *bdi = inode_to_bdi(inode);
struct address_space *mapping = inode->i_mapping;
struct bdi_writeback *old_wb = inode->i_wb;
struct bdi_writeback *new_wb = isw->new_wb;
@@ -344,6 +355,12 @@ static void inode_switch_wbs_work_fn(struct work_struct *work)
bool switched = false;
/*
+ * If @inode switches cgwb membership while sync_inodes_sb() is
+ * being issued, sync_inodes_sb() might miss it. Synchronize.
+ */
+ down_read(&bdi->wb_switch_rwsem);
+
+ /*
* By the time control reaches here, RCU grace period has passed
* since I_WB_SWITCH assertion and all wb stat update transactions
* between unlocked_inode_to_wb_begin/end() are guaranteed to be
@@ -428,6 +445,8 @@ skip_switch:
spin_unlock(&new_wb->list_lock);
spin_unlock(&old_wb->list_lock);
+ up_read(&bdi->wb_switch_rwsem);
+
if (switched) {
wb_wakeup(new_wb);
wb_put(old_wb);
@@ -468,9 +487,18 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id)
if (inode->i_state & I_WB_SWITCH)
return;
+ /*
+ * Avoid starting new switches while sync_inodes_sb() is in
+ * progress. Otherwise, if the down_write protected issue path
+ * blocks heavily, we might end up starting a large number of
+ * switches which will block on the rwsem.
+ */
+ if (!down_read_trylock(&bdi->wb_switch_rwsem))
+ return;
+
isw = kzalloc(sizeof(*isw), GFP_ATOMIC);
if (!isw)
- return;
+ goto out_unlock;
/* find and pin the new wb */
rcu_read_lock();
@@ -504,12 +532,14 @@ static void inode_switch_wbs(struct inode *inode, int new_wb_id)
* Let's continue after I_WB_SWITCH is guaranteed to be visible.
*/
call_rcu(&isw->rcu_head, inode_switch_wbs_rcu_fn);
- return;
+ goto out_unlock;
out_free:
if (isw->new_wb)
wb_put(isw->new_wb);
kfree(isw);
+out_unlock:
+ up_read(&bdi->wb_switch_rwsem);
}
/**
@@ -887,6 +917,9 @@ fs_initcall(cgroup_writeback_init);
#else /* CONFIG_CGROUP_WRITEBACK */
+static void bdi_down_write_wb_switch_rwsem(struct backing_dev_info *bdi) { }
+static void bdi_up_write_wb_switch_rwsem(struct backing_dev_info *bdi) { }
+
static struct bdi_writeback *
locked_inode_to_wb_and_lock_list(struct inode *inode)
__releases(&inode->i_lock)
@@ -2413,8 +2446,11 @@ void sync_inodes_sb(struct super_block *sb)
return;
WARN_ON(!rwsem_is_locked(&sb->s_umount));
+ /* protect against inode wb switch, see inode_switch_wbs_work_fn() */
+ bdi_down_write_wb_switch_rwsem(bdi);
bdi_split_work_to_wbs(bdi, &work, false);
wb_wait_for_completion(bdi, &done);
+ bdi_up_write_wb_switch_rwsem(bdi);
wait_sb_inodes(sb);
}