[PATCH] f2fs: move f2fs_balance_fs from truncate to punch_hole

[PATCH] f2fs: move f2fs_balance_fs from truncate to punch_hole

[Jason Hrycay]

From: Jason Hrycay <jason.hrycay@motorola.com>

Move the f2fs_balance_fs out of the truncate_hole function and only
perform that in punch_hole use case.  The commit:

  ed60b1644e7f7e5dd67d21caf7e4425dff05dad0

intended to do this but moved it into truncate_hole to cover more
cases.  However, a deadlock scenario is possible when deleting an inode
entry under specific conditions:

 f2fs_delete_entry()
     mutex_lock_op(sbi, DENTRY_OPS);
     truncate_hole()
         f2fs_balance_fs()
             mutex_lock(&sbi->gc_mutex);
             f2fs_gc()
                 write_checkpoint()
                     block_operations()
                         mutex_lock_op(sbi, DENTRY_OPS);

Lets move it into the punch_hole case to cover the original intent of
avoiding it during fallocate's expand_inode_data case.

Change-Id: I29f8ea1056b0b88b70ba8652d901b6e8431bb27e
Signed-off-by: Jason Hrycay <jason.hrycay@motorola.com>
---
 fs/f2fs/file.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index e031f57..155b362 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -390,8 +390,6 @@ int truncate_hole(struct inode *inode, pgoff_t pg_start, pgoff_t pg_end)
 		struct dnode_of_data dn;
 		struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);

-		f2fs_balance_fs(sbi);
-
 		mutex_lock_op(sbi, DATA_TRUNC);
 		set_new_dnode(&dn, inode, NULL, NULL, 0);
 		err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
@@ -435,6 +433,9 @@ static int punch_hole(struct inode *inode, loff_t offset, loff_t len, int mode)
 		if (pg_start < pg_end) {
 			struct address_space *mapping = inode->i_mapping;
 			loff_t blk_start, blk_end;
+			struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
+
+			f2fs_balance_fs(sbi);

 			blk_start = pg_start << PAGE_CACHE_SHIFT;
 			blk_end = pg_end << PAGE_CACHE_SHIFT;
-- 1.8.0

Re: [PATCH] f2fs: move f2fs_balance_fs from truncate to punch_hole

[Namjae Jeon]

2013/4/9, Jason Hrycay <jhrycay@gmail.com>:
> From: Jason Hrycay <jason.hrycay@motorola.com>
>
> Move the f2fs_balance_fs out of the truncate_hole function and only
> perform that in punch_hole use case.  The commit:
>
>   ed60b1644e7f7e5dd67d21caf7e4425dff05dad0
>
> intended to do this but moved it into truncate_hole to cover more
> cases.  However, a deadlock scenario is possible when deleting an inode
> entry under specific conditions:
>
>  f2fs_delete_entry()
>      mutex_lock_op(sbi, DENTRY_OPS);
>      truncate_hole()
>          f2fs_balance_fs()
>              mutex_lock(&sbi->gc_mutex);
>              f2fs_gc()
>                  write_checkpoint()
>                      block_operations()
>                          mutex_lock_op(sbi, DENTRY_OPS);
>
> Lets move it into the punch_hole case to cover the original intent of
> avoiding it during fallocate's expand_inode_data case.
>
> Change-Id: I29f8ea1056b0b88b70ba8652d901b6e8431bb27e
> Signed-off-by: Jason Hrycay <jason.hrycay@motorola.com>
Hi,
With the latest commit 9995bf953a83749abd9fa22f72ab2b0be341025a
About introducing the global locking method in ‘f2fs’,
I think we no longer will have a case of deadlock happening in this path.

Thanks.

Re: [PATCH] f2fs: move f2fs_balance_fs from truncate to punch_hole

[Jaegeuk Kim]

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Hi,

2013-04-08 (월), 20:16 -0500, Jason Hrycay:
> From: Jason Hrycay <jason.hrycay@motorola.com>
> 
> Move the f2fs_balance_fs out of the truncate_hole function and only
> perform that in punch_hole use case.  The commit:
> 
>   ed60b1644e7f7e5dd67d21caf7e4425dff05dad0
> 
> intended to do this but moved it into truncate_hole to cover more
> cases.  However, a deadlock scenario is possible when deleting an inode
> entry under specific conditions:
> 
>  f2fs_delete_entry()
>      mutex_lock_op(sbi, DENTRY_OPS);
>      truncate_hole()
>          f2fs_balance_fs()
>              mutex_lock(&sbi->gc_mutex);
>              f2fs_gc()
>                  write_checkpoint()
>                      block_operations()
>                          mutex_lock_op(sbi, DENTRY_OPS);
> 
> Lets move it into the punch_hole case to cover the original intent of
> avoiding it during fallocate's expand_inode_data case.

Agreed.
Thanks,

> 
> Change-Id: I29f8ea1056b0b88b70ba8652d901b6e8431bb27e
> Signed-off-by: Jason Hrycay <jason.hrycay@motorola.com>
> ---
>  fs/f2fs/file.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index e031f57..155b362 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -390,8 +390,6 @@ int truncate_hole(struct inode *inode, pgoff_t pg_start, pgoff_t pg_end)
>  		struct dnode_of_data dn;
>  		struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
> 
> -		f2fs_balance_fs(sbi);
> -
>  		mutex_lock_op(sbi, DATA_TRUNC);
>  		set_new_dnode(&dn, inode, NULL, NULL, 0);
>  		err = get_dnode_of_data(&dn, index, LOOKUP_NODE);
> @@ -435,6 +433,9 @@ static int punch_hole(struct inode *inode, loff_t offset, loff_t len, int mode)
>  		if (pg_start < pg_end) {
>  			struct address_space *mapping = inode->i_mapping;
>  			loff_t blk_start, blk_end;
> +			struct f2fs_sb_info *sbi = F2FS_SB(inode->i_sb);
> +
> +			f2fs_balance_fs(sbi);
> 
>  			blk_start = pg_start << PAGE_CACHE_SHIFT;
>  			blk_end = pg_end << PAGE_CACHE_SHIFT;
> -- 1.8.0

-- 
Jaegeuk Kim
Samsung

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Re: [PATCH] f2fs: move f2fs_balance_fs from truncate to punch_hole

[Jaegeuk Kim]

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2013-04-09 (화), 15:46 +0900, Namjae Jeon:
> 2013/4/9, Jason Hrycay <jhrycay@gmail.com>:
> > From: Jason Hrycay <jason.hrycay@motorola.com>
> >
> > Move the f2fs_balance_fs out of the truncate_hole function and only
> > perform that in punch_hole use case.  The commit:
> >
> >   ed60b1644e7f7e5dd67d21caf7e4425dff05dad0
> >
> > intended to do this but moved it into truncate_hole to cover more
> > cases.  However, a deadlock scenario is possible when deleting an inode
> > entry under specific conditions:
> >
> >  f2fs_delete_entry()
> >      mutex_lock_op(sbi, DENTRY_OPS);
> >      truncate_hole()
> >          f2fs_balance_fs()
> >              mutex_lock(&sbi->gc_mutex);
> >              f2fs_gc()
> >                  write_checkpoint()
> >                      block_operations()
> >                          mutex_lock_op(sbi, DENTRY_OPS);
> >
> > Lets move it into the punch_hole case to cover the original intent of
> > avoiding it during fallocate's expand_inode_data case.
> >
> > Change-Id: I29f8ea1056b0b88b70ba8652d901b6e8431bb27e
> > Signed-off-by: Jason Hrycay <jason.hrycay@motorola.com>
> Hi,
> With the latest commit 9995bf953a83749abd9fa22f72ab2b0be341025a
> About introducing the global locking method in ‘f2fs’,
> I think we no longer will have a case of deadlock happening in this path.

Hi, Namjae.
I found that this bug still exists in the new locking model.
Please see the v3 patch. :)
Thanks,

> 
> Thanks.

-- 
Jaegeuk Kim
Samsung

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