* [PATCH 1/4] ext4: serialize dio nonlocked reads with defrag workers
@ 2012-09-04 17:22 Dmitry Monakhov
2012-09-04 17:22 ` [PATCH 2/4] ext4: serialize unlocked dio reads with truncate Dmitry Monakhov
` (2 more replies)
0 siblings, 3 replies; 6+ messages in thread
From: Dmitry Monakhov @ 2012-09-04 17:22 UTC (permalink / raw)
To: linux-ext4; +Cc: jack, Dmitry Monakhov
Inode's block defrag and ext4_change_inode_journal_flag() may
affect nonlocked DIO reads result, so proper synchronization
required.
- add missed inode_dio_wait() calls where appropriate
- recheck ext4_should_dioread_nolock under extra i_dio_count reference.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
fs/ext4/ext4.h | 2 ++
fs/ext4/ext4_jbd2.h | 2 ++
fs/ext4/indirect.c | 12 ++++++++++++
fs/ext4/inode.c | 5 +++++
fs/ext4/move_extent.c | 10 ++++++++++
5 files changed, 31 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index f9024a6..36e8b84 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1349,6 +1349,8 @@ enum {
EXT4_STATE_DIO_UNWRITTEN, /* need convert on dio done*/
EXT4_STATE_NEWENTRY, /* File just added to dir */
EXT4_STATE_DELALLOC_RESERVED, /* blks already reserved for delalloc */
+ EXT4_STATE_DIOREAD_LOCK, /* Disable support for dio read
+ nolocking */
};
#define EXT4_INODE_BIT_FNS(name, field, offset) \
diff --git a/fs/ext4/ext4_jbd2.h b/fs/ext4/ext4_jbd2.h
index 56d258c..318d177 100644
--- a/fs/ext4/ext4_jbd2.h
+++ b/fs/ext4/ext4_jbd2.h
@@ -399,6 +399,8 @@ static inline int ext4_should_dioread_nolock(struct inode *inode)
return 0;
if (ext4_should_journal_data(inode))
return 0;
+ if (ext4_test_inode_state(inode, EXT4_STATE_DIOREAD_LOCK))
+ return 0;
return 1;
}
diff --git a/fs/ext4/indirect.c b/fs/ext4/indirect.c
index 830e1b2..ba40309 100644
--- a/fs/ext4/indirect.c
+++ b/fs/ext4/indirect.c
@@ -812,10 +812,22 @@ retry:
ext4_flush_completed_IO(inode);
mutex_unlock(&inode->i_mutex);
}
+ /*
+ * Inode's locking behaviour may change due to number
+ * of reasons, in order to be shure that nolock dioreads
+ * is still allowed we have to recheck inode's flags
+ * while i_dio_count > 0
+ */
+ atomic_inc(&inode->i_dio_count);
+ if (!unlikely(ext4_should_dioread_nolock(inode))) {
+ inode_dio_done(inode);
+ goto retry;
+ }
ret = __blockdev_direct_IO(rw, iocb, inode,
inode->i_sb->s_bdev, iov,
offset, nr_segs,
ext4_get_block, NULL, NULL, 0);
+ inode_dio_done(inode);
} else {
ret = blockdev_direct_IO(rw, iocb, inode, iov,
offset, nr_segs, ext4_get_block);
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index d12d30e..58ef61a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4741,6 +4741,10 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
return err;
}
+ /* Wait for all existing dio workers */
+ ext4_set_inode_state(inode, EXT4_STATE_DIOREAD_LOCK);
+ inode_dio_wait(inode);
+
jbd2_journal_lock_updates(journal);
/*
@@ -4760,6 +4764,7 @@ int ext4_change_inode_journal_flag(struct inode *inode, int val)
ext4_set_aops(inode);
jbd2_journal_unlock_updates(journal);
+ ext4_clear_inode_state(inode, EXT4_STATE_DIOREAD_LOCK);
/* Finally we can mark the inode as dirty. */
diff --git a/fs/ext4/move_extent.c b/fs/ext4/move_extent.c
index c5826c6..a6a4278 100644
--- a/fs/ext4/move_extent.c
+++ b/fs/ext4/move_extent.c
@@ -1213,6 +1213,14 @@ ext4_move_extents(struct file *o_filp, struct file *d_filp,
ret1 = mext_inode_double_lock(orig_inode, donor_inode);
if (ret1 < 0)
return ret1;
+ /* Protect inodes against DIO workers
+ * - Disable dio nonlock reads, so all new dio workers will block
+ * on i_mutex.
+ * - wait for existing DIO in flight */
+ ext4_set_inode_state(orig_inode, EXT4_STATE_DIOREAD_LOCK);
+ ext4_set_inode_state(donor_inode, EXT4_STATE_DIOREAD_LOCK);
+ inode_dio_wait(orig_inode);
+ inode_dio_wait(donor_inode);
/* Protect extent tree against block allocations via delalloc */
double_down_write_data_sem(orig_inode, donor_inode);
@@ -1412,6 +1420,8 @@ out:
kfree(holecheck_path);
}
double_up_write_data_sem(orig_inode, donor_inode);
+ ext4_clear_inode_state(orig_inode, EXT4_STATE_DIOREAD_LOCK);
+ ext4_clear_inode_state(donor_inode, EXT4_STATE_DIOREAD_LOCK);
ret2 = mext_inode_double_unlock(orig_inode, donor_inode);
if (ret1)
--
1.7.7.6
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 2/4] ext4: serialize unlocked dio reads with truncate
2012-09-04 17:22 [PATCH 1/4] ext4: serialize dio nonlocked reads with defrag workers Dmitry Monakhov
@ 2012-09-04 17:22 ` Dmitry Monakhov
2012-09-04 17:22 ` [PATCH 3/4] ext4: endless truncate due to nonlocked dio readers Dmitry Monakhov
2012-09-04 17:22 ` [PATCH 4/4] ext4: serialize truncate with owerwrite DIO workers Dmitry Monakhov
2 siblings, 0 replies; 6+ messages in thread
From: Dmitry Monakhov @ 2012-09-04 17:22 UTC (permalink / raw)
To: linux-ext4; +Cc: jack, Dmitry Monakhov
Current serialization will works only for DIO which holds
i_mutex, but nonlocked DIO following race is possible:
dio_nolock_read_task truncate_task
->ext4_setattr()
->inode_dio_wait()
->ext4_ext_direct_IO
->ext4_ind_direct_IO
->__blockdev_direct_IO
->ext4_get_block
->truncate_setsize()
->ext4_truncate()
#alloc truncated blocks
#to other inode
->submit_io()
#INFORMATION LEAK
In order to serialize with unlocked DIO reads we have to
rearrange wait sequence
1) update i_size first
2) wait for outstanding DIO requests
3) and only after that truncate inode blocks
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
fs/ext4/inode.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 58ef61a..709ec5a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4304,7 +4304,6 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
}
if (attr->ia_valid & ATTR_SIZE) {
- inode_dio_wait(inode);
if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
@@ -4355,6 +4354,7 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
if (attr->ia_valid & ATTR_SIZE) {
if (attr->ia_size != i_size_read(inode))
truncate_setsize(inode, attr->ia_size);
+ inode_dio_wait(inode);
ext4_truncate(inode);
}
--
1.7.7.6
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 3/4] ext4: endless truncate due to nonlocked dio readers
2012-09-04 17:22 [PATCH 1/4] ext4: serialize dio nonlocked reads with defrag workers Dmitry Monakhov
2012-09-04 17:22 ` [PATCH 2/4] ext4: serialize unlocked dio reads with truncate Dmitry Monakhov
@ 2012-09-04 17:22 ` Dmitry Monakhov
2012-09-04 17:31 ` Dmitry Monakhov
2012-09-04 17:22 ` [PATCH 4/4] ext4: serialize truncate with owerwrite DIO workers Dmitry Monakhov
2 siblings, 1 reply; 6+ messages in thread
From: Dmitry Monakhov @ 2012-09-04 17:22 UTC (permalink / raw)
To: linux-ext4; +Cc: jack, Dmitry Monakhov
If we have enough aggressive DIO readers, truncate will wait
forever inside inode_dio_wait(). It is reasonable to disable
nonlock DIO read optimization during truncate.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
fs/ext4/inode.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 709ec5a..e696f19 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4354,7 +4354,9 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
if (attr->ia_valid & ATTR_SIZE) {
if (attr->ia_size != i_size_read(inode))
truncate_setsize(inode, attr->ia_size);
+ ext4_set_inode_state(inode, EXT4_STATE_DIOREAD_LOCK);
inode_dio_wait(inode);
+ ext4_set_inode_state(inode, EXT4_STATE_DIOREAD_LOCK);
ext4_truncate(inode);
}
--
1.7.7.6
^ permalink raw reply related [flat|nested] 6+ messages in thread
* [PATCH 4/4] ext4: serialize truncate with owerwrite DIO workers
2012-09-04 17:22 [PATCH 1/4] ext4: serialize dio nonlocked reads with defrag workers Dmitry Monakhov
2012-09-04 17:22 ` [PATCH 2/4] ext4: serialize unlocked dio reads with truncate Dmitry Monakhov
2012-09-04 17:22 ` [PATCH 3/4] ext4: endless truncate due to nonlocked dio readers Dmitry Monakhov
@ 2012-09-04 17:22 ` Dmitry Monakhov
2 siblings, 0 replies; 6+ messages in thread
From: Dmitry Monakhov @ 2012-09-04 17:22 UTC (permalink / raw)
To: linux-ext4; +Cc: jack, Dmitry Monakhov
Jan Kara have spotted interesting issue:
There are potential data corruption issue with direct IO overwrites
racing with truncate:
Like:
dio write truncate_task
->ext4_ext_direct_IO
->overwrite == 1
->down_read(&EXT4_I(inode)->i_data_sem);
->mutex_unlock(&inode->i_mutex);
->ext4_setattr()
->inode_dio_wait()
->truncate_setsize()
->ext4_truncate()
->down_write(&EXT4_I(inode)->i_data_sem);
->__blockdev_direct_IO
->ext4_get_block
->submit_io()
->up_read(&EXT4_I(inode)->i_data_sem);
# truncate data blocks, allocate them to
# other inode - bad stuff happens because
# dio is still in flight.
In order to serialize with truncate dio worker should grab extra i_dio_count
reference before drop i_mutex.
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
fs/ext4/inode.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index e696f19..46606e3 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -3035,6 +3035,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
overwrite = *((int *)iocb->private);
if (overwrite) {
+ atomic_inc(&inode->i_dio_count);
down_read(&EXT4_I(inode)->i_data_sem);
mutex_unlock(&inode->i_mutex);
}
@@ -3134,6 +3135,7 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
if (overwrite) {
up_read(&EXT4_I(inode)->i_data_sem);
mutex_lock(&inode->i_mutex);
+ inode_dio_done(inode);
}
return ret;
--
1.7.7.6
^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH 3/4] ext4: endless truncate due to nonlocked dio readers
2012-09-04 17:22 ` [PATCH 3/4] ext4: endless truncate due to nonlocked dio readers Dmitry Monakhov
@ 2012-09-04 17:31 ` Dmitry Monakhov
0 siblings, 0 replies; 6+ messages in thread
From: Dmitry Monakhov @ 2012-09-04 17:31 UTC (permalink / raw)
To: linux-ext4; +Cc: jack
On Tue, 4 Sep 2012 21:22:50 +0400, Dmitry Monakhov <dmonakhov@openvz.org> wrote:
> If we have enough aggressive DIO readers, truncate will wait
> forever inside inode_dio_wait(). It is reasonable to disable
> nonlock DIO read optimization during truncate.
>
> Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
> ---
> fs/ext4/inode.c | 2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 709ec5a..e696f19 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -4354,7 +4354,9 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
> if (attr->ia_valid & ATTR_SIZE) {
> if (attr->ia_size != i_size_read(inode))
> truncate_setsize(inode, attr->ia_size);
> + ext4_set_inode_state(inode, EXT4_STATE_DIOREAD_LOCK);
> inode_dio_wait(inode);
> + ext4_set_inode_state(inode, EXT4_STATE_DIOREAD_LOCK);
OOps, sorry ^^^^^^^^^^^^^^^ this is wrong
should be ext4_clear_inode_state()
> ext4_truncate(inode);
> }
>
> --
> 1.7.7.6
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH 2/4] ext4: serialize unlocked dio reads with truncate
2012-09-04 17:36 [PATCH 1/4] ext4: serialize dio nonlocked reads with defrag workers Dmitry Monakhov
@ 2012-09-04 17:36 ` Dmitry Monakhov
0 siblings, 0 replies; 6+ messages in thread
From: Dmitry Monakhov @ 2012-09-04 17:36 UTC (permalink / raw)
To: linux-ext4; +Cc: jack, Dmitry Monakhov
Current serialization will works only for DIO which holds
i_mutex, but nonlocked DIO following race is possible:
dio_nolock_read_task truncate_task
->ext4_setattr()
->inode_dio_wait()
->ext4_ext_direct_IO
->ext4_ind_direct_IO
->__blockdev_direct_IO
->ext4_get_block
->truncate_setsize()
->ext4_truncate()
#alloc truncated blocks
#to other inode
->submit_io()
#INFORMATION LEAK
In order to serialize with unlocked DIO reads we have to
rearrange wait sequence
1) update i_size first
2) wait for outstanding DIO requests
3) and only after that truncate inode blocks
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org>
---
fs/ext4/inode.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 58ef61a..709ec5a 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4304,7 +4304,6 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
}
if (attr->ia_valid & ATTR_SIZE) {
- inode_dio_wait(inode);
if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
@@ -4355,6 +4354,7 @@ int ext4_setattr(struct dentry *dentry, struct iattr *attr)
if (attr->ia_valid & ATTR_SIZE) {
if (attr->ia_size != i_size_read(inode))
truncate_setsize(inode, attr->ia_size);
+ inode_dio_wait(inode);
ext4_truncate(inode);
}
--
1.7.7.6
^ permalink raw reply related [flat|nested] 6+ messages in thread
end of thread, other threads:[~2012-09-04 17:37 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2012-09-04 17:22 [PATCH 1/4] ext4: serialize dio nonlocked reads with defrag workers Dmitry Monakhov
2012-09-04 17:22 ` [PATCH 2/4] ext4: serialize unlocked dio reads with truncate Dmitry Monakhov
2012-09-04 17:22 ` [PATCH 3/4] ext4: endless truncate due to nonlocked dio readers Dmitry Monakhov
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