As Yi Chen reported, there is a potential race case described as below:
Thread A Thread B
- f2fs_ioc_start_atomic_write
- mkwrite
- set_page_dirty
- f2fs_set_page_private(page, 0)
- set_inode_flag(FI_ATOMIC_FILE)
- mkwrite same page
- set_page_dirty
- f2fs_register_inmem_page
- f2fs_set_page_private(ATOMIC_WRITTEN_PAGE)
failed due to PagePrivate flag has been set
- list_add_tail
- truncate_inode_pages
- f2fs_invalidate_page
- clear page private but w/o remove it from
inmem_list
- set page->mapping to NULL
- f2fs_ioc_commit_atomic_write
- __f2fs_commit_inmem_pages
- __revoke_inmem_pages
- f2fs_put_page panic as page->mapping is NULL
The root cause is we missed to keep isolation of atomic write in the case
of start_atomic_write vs mkwrite, let start_atomic_write helds i_mmap_sem
lock to avoid this issue.
Reported-by: Yi Chen <[email protected]>
Signed-off-by: Chao Yu <[email protected]>
---
v3:
- rebase to last dev branch
- update commit message because this patch fixes a different racing issue
of atomic write
fs/f2fs/file.c | 3 +++
fs/f2fs/segment.c | 6 ++++++
2 files changed, 9 insertions(+)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index d697c8900fa7..6284b2f4a60b 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -2054,6 +2054,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
goto out;
down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
+ down_write(&F2FS_I(inode)->i_mmap_sem);
/*
* Should wait end_io to count F2FS_WB_CP_DATA correctly by
@@ -2064,6 +2065,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
inode->i_ino, get_dirty_pages(inode));
ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX);
if (ret) {
+ up_write(&F2FS_I(inode)->i_mmap_sem);
up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
goto out;
}
@@ -2077,6 +2079,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
/* add inode in inmem_list first and set atomic_file */
set_inode_flag(inode, FI_ATOMIC_FILE);
clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST);
+ up_write(&F2FS_I(inode)->i_mmap_sem);
up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
f2fs_update_time(F2FS_I_SB(inode), REQ_TIME);
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 0cb1ca88d4aa..78c8342f52fd 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -325,6 +325,7 @@ void f2fs_drop_inmem_pages(struct inode *inode)
struct f2fs_inode_info *fi = F2FS_I(inode);
do {
+ down_write(&F2FS_I(inode)->i_mmap_sem);
mutex_lock(&fi->inmem_lock);
if (list_empty(&fi->inmem_pages)) {
fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0;
@@ -339,11 +340,13 @@ void f2fs_drop_inmem_pages(struct inode *inode)
spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
mutex_unlock(&fi->inmem_lock);
+ up_write(&F2FS_I(inode)->i_mmap_sem);
break;
}
__revoke_inmem_pages(inode, &fi->inmem_pages,
true, false, true);
mutex_unlock(&fi->inmem_lock);
+ up_write(&F2FS_I(inode)->i_mmap_sem);
} while (1);
}
@@ -468,6 +471,7 @@ int f2fs_commit_inmem_pages(struct inode *inode)
f2fs_balance_fs(sbi, true);
down_write(&fi->i_gc_rwsem[WRITE]);
+ down_write(&F2FS_I(inode)->i_mmap_sem);
f2fs_lock_op(sbi);
set_inode_flag(inode, FI_ATOMIC_COMMIT);
@@ -479,6 +483,8 @@ int f2fs_commit_inmem_pages(struct inode *inode)
clear_inode_flag(inode, FI_ATOMIC_COMMIT);
f2fs_unlock_op(sbi);
+
+ up_write(&F2FS_I(inode)->i_mmap_sem);
up_write(&fi->i_gc_rwsem[WRITE]);
return err;
--
2.29.2
On 04/12, Chao Yu wrote:
> As Yi Chen reported, there is a potential race case described as below:
>
> Thread A Thread B
> - f2fs_ioc_start_atomic_write
> - mkwrite
> - set_page_dirty
> - f2fs_set_page_private(page, 0)
> - set_inode_flag(FI_ATOMIC_FILE)
> - mkwrite same page
> - set_page_dirty
> - f2fs_register_inmem_page
> - f2fs_set_page_private(ATOMIC_WRITTEN_PAGE)
> failed due to PagePrivate flag has been set
> - list_add_tail
> - truncate_inode_pages
> - f2fs_invalidate_page
> - clear page private but w/o remove it from
> inmem_list
> - set page->mapping to NULL
> - f2fs_ioc_commit_atomic_write
> - __f2fs_commit_inmem_pages
> - __revoke_inmem_pages
> - f2fs_put_page panic as page->mapping is NULL
>
> The root cause is we missed to keep isolation of atomic write in the case
> of start_atomic_write vs mkwrite, let start_atomic_write helds i_mmap_sem
> lock to avoid this issue.
My only concern is performance regression. Could you please verify the numbers?
>
> Reported-by: Yi Chen <[email protected]>
> Signed-off-by: Chao Yu <[email protected]>
> ---
> v3:
> - rebase to last dev branch
> - update commit message because this patch fixes a different racing issue
> of atomic write
> fs/f2fs/file.c | 3 +++
> fs/f2fs/segment.c | 6 ++++++
> 2 files changed, 9 insertions(+)
>
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index d697c8900fa7..6284b2f4a60b 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -2054,6 +2054,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
> goto out;
>
> down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> + down_write(&F2FS_I(inode)->i_mmap_sem);
>
> /*
> * Should wait end_io to count F2FS_WB_CP_DATA correctly by
> @@ -2064,6 +2065,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
> inode->i_ino, get_dirty_pages(inode));
> ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX);
> if (ret) {
> + up_write(&F2FS_I(inode)->i_mmap_sem);
> up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> goto out;
> }
> @@ -2077,6 +2079,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
> /* add inode in inmem_list first and set atomic_file */
> set_inode_flag(inode, FI_ATOMIC_FILE);
> clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST);
> + up_write(&F2FS_I(inode)->i_mmap_sem);
> up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
>
> f2fs_update_time(F2FS_I_SB(inode), REQ_TIME);
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 0cb1ca88d4aa..78c8342f52fd 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -325,6 +325,7 @@ void f2fs_drop_inmem_pages(struct inode *inode)
> struct f2fs_inode_info *fi = F2FS_I(inode);
>
> do {
> + down_write(&F2FS_I(inode)->i_mmap_sem);
> mutex_lock(&fi->inmem_lock);
> if (list_empty(&fi->inmem_pages)) {
> fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0;
> @@ -339,11 +340,13 @@ void f2fs_drop_inmem_pages(struct inode *inode)
> spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
>
> mutex_unlock(&fi->inmem_lock);
> + up_write(&F2FS_I(inode)->i_mmap_sem);
> break;
> }
> __revoke_inmem_pages(inode, &fi->inmem_pages,
> true, false, true);
> mutex_unlock(&fi->inmem_lock);
> + up_write(&F2FS_I(inode)->i_mmap_sem);
> } while (1);
> }
>
> @@ -468,6 +471,7 @@ int f2fs_commit_inmem_pages(struct inode *inode)
> f2fs_balance_fs(sbi, true);
>
> down_write(&fi->i_gc_rwsem[WRITE]);
> + down_write(&F2FS_I(inode)->i_mmap_sem);
>
> f2fs_lock_op(sbi);
> set_inode_flag(inode, FI_ATOMIC_COMMIT);
> @@ -479,6 +483,8 @@ int f2fs_commit_inmem_pages(struct inode *inode)
> clear_inode_flag(inode, FI_ATOMIC_COMMIT);
>
> f2fs_unlock_op(sbi);
> +
> + up_write(&F2FS_I(inode)->i_mmap_sem);
> up_write(&fi->i_gc_rwsem[WRITE]);
>
> return err;
> --
> 2.29.2
On 2021/4/13 11:27, Jaegeuk Kim wrote:
> On 04/12, Chao Yu wrote:
>> As Yi Chen reported, there is a potential race case described as below:
>>
>> Thread A Thread B
>> - f2fs_ioc_start_atomic_write
>> - mkwrite
>> - set_page_dirty
>> - f2fs_set_page_private(page, 0)
>> - set_inode_flag(FI_ATOMIC_FILE)
>> - mkwrite same page
>> - set_page_dirty
>> - f2fs_register_inmem_page
>> - f2fs_set_page_private(ATOMIC_WRITTEN_PAGE)
>> failed due to PagePrivate flag has been set
>> - list_add_tail
>> - truncate_inode_pages
>> - f2fs_invalidate_page
>> - clear page private but w/o remove it from
>> inmem_list
>> - set page->mapping to NULL
>> - f2fs_ioc_commit_atomic_write
>> - __f2fs_commit_inmem_pages
>> - __revoke_inmem_pages
>> - f2fs_put_page panic as page->mapping is NULL
>>
>> The root cause is we missed to keep isolation of atomic write in the case
>> of start_atomic_write vs mkwrite, let start_atomic_write helds i_mmap_sem
>> lock to avoid this issue.
>
> My only concern is performance regression. Could you please verify the numbers?
Do you have specific test script?
IIRC, the scenario you mean is multi-threads write/mmap the same db, right?
Thanks,
>
>>
>> Reported-by: Yi Chen <[email protected]>
>> Signed-off-by: Chao Yu <[email protected]>
>> ---
>> v3:
>> - rebase to last dev branch
>> - update commit message because this patch fixes a different racing issue
>> of atomic write
>> fs/f2fs/file.c | 3 +++
>> fs/f2fs/segment.c | 6 ++++++
>> 2 files changed, 9 insertions(+)
>>
>> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
>> index d697c8900fa7..6284b2f4a60b 100644
>> --- a/fs/f2fs/file.c
>> +++ b/fs/f2fs/file.c
>> @@ -2054,6 +2054,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
>> goto out;
>>
>> down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
>> + down_write(&F2FS_I(inode)->i_mmap_sem);
>>
>> /*
>> * Should wait end_io to count F2FS_WB_CP_DATA correctly by
>> @@ -2064,6 +2065,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
>> inode->i_ino, get_dirty_pages(inode));
>> ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX);
>> if (ret) {
>> + up_write(&F2FS_I(inode)->i_mmap_sem);
>> up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
>> goto out;
>> }
>> @@ -2077,6 +2079,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
>> /* add inode in inmem_list first and set atomic_file */
>> set_inode_flag(inode, FI_ATOMIC_FILE);
>> clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST);
>> + up_write(&F2FS_I(inode)->i_mmap_sem);
>> up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
>>
>> f2fs_update_time(F2FS_I_SB(inode), REQ_TIME);
>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>> index 0cb1ca88d4aa..78c8342f52fd 100644
>> --- a/fs/f2fs/segment.c
>> +++ b/fs/f2fs/segment.c
>> @@ -325,6 +325,7 @@ void f2fs_drop_inmem_pages(struct inode *inode)
>> struct f2fs_inode_info *fi = F2FS_I(inode);
>>
>> do {
>> + down_write(&F2FS_I(inode)->i_mmap_sem);
>> mutex_lock(&fi->inmem_lock);
>> if (list_empty(&fi->inmem_pages)) {
>> fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0;
>> @@ -339,11 +340,13 @@ void f2fs_drop_inmem_pages(struct inode *inode)
>> spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
>>
>> mutex_unlock(&fi->inmem_lock);
>> + up_write(&F2FS_I(inode)->i_mmap_sem);
>> break;
>> }
>> __revoke_inmem_pages(inode, &fi->inmem_pages,
>> true, false, true);
>> mutex_unlock(&fi->inmem_lock);
>> + up_write(&F2FS_I(inode)->i_mmap_sem);
>> } while (1);
>> }
>>
>> @@ -468,6 +471,7 @@ int f2fs_commit_inmem_pages(struct inode *inode)
>> f2fs_balance_fs(sbi, true);
>>
>> down_write(&fi->i_gc_rwsem[WRITE]);
>> + down_write(&F2FS_I(inode)->i_mmap_sem);
>>
>> f2fs_lock_op(sbi);
>> set_inode_flag(inode, FI_ATOMIC_COMMIT);
>> @@ -479,6 +483,8 @@ int f2fs_commit_inmem_pages(struct inode *inode)
>> clear_inode_flag(inode, FI_ATOMIC_COMMIT);
>>
>> f2fs_unlock_op(sbi);
>> +
>> + up_write(&F2FS_I(inode)->i_mmap_sem);
>> up_write(&fi->i_gc_rwsem[WRITE]);
>>
>> return err;
>> --
>> 2.29.2
> .
>
On 04/13, Chao Yu wrote:
> On 2021/4/13 11:27, Jaegeuk Kim wrote:
> > On 04/12, Chao Yu wrote:
> > > As Yi Chen reported, there is a potential race case described as below:
> > >
> > > Thread A Thread B
> > > - f2fs_ioc_start_atomic_write
> > > - mkwrite
> > > - set_page_dirty
> > > - f2fs_set_page_private(page, 0)
> > > - set_inode_flag(FI_ATOMIC_FILE)
> > > - mkwrite same page
> > > - set_page_dirty
> > > - f2fs_register_inmem_page
> > > - f2fs_set_page_private(ATOMIC_WRITTEN_PAGE)
> > > failed due to PagePrivate flag has been set
> > > - list_add_tail
> > > - truncate_inode_pages
> > > - f2fs_invalidate_page
> > > - clear page private but w/o remove it from
> > > inmem_list
> > > - set page->mapping to NULL
> > > - f2fs_ioc_commit_atomic_write
> > > - __f2fs_commit_inmem_pages
> > > - __revoke_inmem_pages
> > > - f2fs_put_page panic as page->mapping is NULL
> > >
> > > The root cause is we missed to keep isolation of atomic write in the case
> > > of start_atomic_write vs mkwrite, let start_atomic_write helds i_mmap_sem
> > > lock to avoid this issue.
> >
> > My only concern is performance regression. Could you please verify the numbers?
>
> Do you have specific test script?
>
> IIRC, the scenario you mean is multi-threads write/mmap the same db, right?
I suggest to run sqlite transaction/check operations in android devices in parallel.
>
> Thanks,
>
> >
> > >
> > > Reported-by: Yi Chen <[email protected]>
> > > Signed-off-by: Chao Yu <[email protected]>
> > > ---
> > > v3:
> > > - rebase to last dev branch
> > > - update commit message because this patch fixes a different racing issue
> > > of atomic write
> > > fs/f2fs/file.c | 3 +++
> > > fs/f2fs/segment.c | 6 ++++++
> > > 2 files changed, 9 insertions(+)
> > >
> > > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > > index d697c8900fa7..6284b2f4a60b 100644
> > > --- a/fs/f2fs/file.c
> > > +++ b/fs/f2fs/file.c
> > > @@ -2054,6 +2054,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
> > > goto out;
> > > down_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> > > + down_write(&F2FS_I(inode)->i_mmap_sem);
> > > /*
> > > * Should wait end_io to count F2FS_WB_CP_DATA correctly by
> > > @@ -2064,6 +2065,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
> > > inode->i_ino, get_dirty_pages(inode));
> > > ret = filemap_write_and_wait_range(inode->i_mapping, 0, LLONG_MAX);
> > > if (ret) {
> > > + up_write(&F2FS_I(inode)->i_mmap_sem);
> > > up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> > > goto out;
> > > }
> > > @@ -2077,6 +2079,7 @@ static int f2fs_ioc_start_atomic_write(struct file *filp)
> > > /* add inode in inmem_list first and set atomic_file */
> > > set_inode_flag(inode, FI_ATOMIC_FILE);
> > > clear_inode_flag(inode, FI_ATOMIC_REVOKE_REQUEST);
> > > + up_write(&F2FS_I(inode)->i_mmap_sem);
> > > up_write(&F2FS_I(inode)->i_gc_rwsem[WRITE]);
> > > f2fs_update_time(F2FS_I_SB(inode), REQ_TIME);
> > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > > index 0cb1ca88d4aa..78c8342f52fd 100644
> > > --- a/fs/f2fs/segment.c
> > > +++ b/fs/f2fs/segment.c
> > > @@ -325,6 +325,7 @@ void f2fs_drop_inmem_pages(struct inode *inode)
> > > struct f2fs_inode_info *fi = F2FS_I(inode);
> > > do {
> > > + down_write(&F2FS_I(inode)->i_mmap_sem);
> > > mutex_lock(&fi->inmem_lock);
> > > if (list_empty(&fi->inmem_pages)) {
> > > fi->i_gc_failures[GC_FAILURE_ATOMIC] = 0;
> > > @@ -339,11 +340,13 @@ void f2fs_drop_inmem_pages(struct inode *inode)
> > > spin_unlock(&sbi->inode_lock[ATOMIC_FILE]);
> > > mutex_unlock(&fi->inmem_lock);
> > > + up_write(&F2FS_I(inode)->i_mmap_sem);
> > > break;
> > > }
> > > __revoke_inmem_pages(inode, &fi->inmem_pages,
> > > true, false, true);
> > > mutex_unlock(&fi->inmem_lock);
> > > + up_write(&F2FS_I(inode)->i_mmap_sem);
> > > } while (1);
> > > }
> > > @@ -468,6 +471,7 @@ int f2fs_commit_inmem_pages(struct inode *inode)
> > > f2fs_balance_fs(sbi, true);
> > > down_write(&fi->i_gc_rwsem[WRITE]);
> > > + down_write(&F2FS_I(inode)->i_mmap_sem);
> > > f2fs_lock_op(sbi);
> > > set_inode_flag(inode, FI_ATOMIC_COMMIT);
> > > @@ -479,6 +483,8 @@ int f2fs_commit_inmem_pages(struct inode *inode)
> > > clear_inode_flag(inode, FI_ATOMIC_COMMIT);
> > > f2fs_unlock_op(sbi);
> > > +
> > > + up_write(&F2FS_I(inode)->i_mmap_sem);
> > > up_write(&fi->i_gc_rwsem[WRITE]);
> > > return err;
> > > --
> > > 2.29.2
> > .
> >