[PATCH] Remove redundant check under lock scope in fallocate()

[PATCH] Remove redundant check under lock scope in fallocate()

[Davide Italiano]

The check for indirect files is already done in ext4_fallocate()
and outside of the lock scope. I removed it entirely from ext4_zero_range
and ext4_collapse range.

Davide Italiano (1):
  ext4: Remove redundant check under lock scope

 fs/ext4/extents.c | 16 ----------------
 1 file changed, 16 deletions(-)

-- 
2.3.4

[PATCH] ext4: Remove redundant check under lock scope

[Davide Italiano]

ext4_zero_range() and ext4_collapse_range() duplicate
the check in ext4_fallocate(). The checks are made with
inode lock held when there's no need for that. Remove them,
reducing the scope of the lock.

Signed-off-by: Davide Italiano <dccitaliano@gmail.com>
---
 fs/ext4/extents.c | 16 ----------------
 1 file changed, 16 deletions(-)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index bed4308..9e6fa09 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4810,15 +4810,6 @@ static long ext4_zero_range(struct file *file, loff_t offset,
 		flags |= EXT4_GET_BLOCKS_KEEP_SIZE;
 
 	mutex_lock(&inode->i_mutex);
-
-	/*
-	 * Indirect files do not support unwritten extnets
-	 */
-	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
-		ret = -EOPNOTSUPP;
-		goto out_mutex;
-	}
-
 	if (!(mode & FALLOC_FL_KEEP_SIZE) &&
 	     offset + len > i_size_read(inode)) {
 		new_size = offset + len;
@@ -5445,13 +5436,6 @@ int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
 		ret = -EINVAL;
 		goto out_mutex;
 	}
-
-	/* Currently just for extent based files */
-	if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
-		ret = -EOPNOTSUPP;
-		goto out_mutex;
-	}

Re: [PATCH] ext4: Remove redundant check under lock scope

[Dmitry Monakhov]

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Davide Italiano <dccitaliano@gmail.com> writes:

> ext4_zero_range() and ext4_collapse_range() duplicate
> the check in ext4_fallocate(). The checks are made with
> inode lock held when there's no need for that. Remove them,
> reducing the scope of the lock.
NAK. Other task can convert indirect<=>extent via
ioctl(, EXT4_IOC_SETFLAGS, flags)
  ->ext4_ext_migrate()
  ->ext4_int_migrate()
So we _must_ recheck EXT4_INODE_EXTENTS after we grab i_mutex.
>
> Signed-off-by: Davide Italiano <dccitaliano@gmail.com>
> ---
>  fs/ext4/extents.c | 16 ----------------
>  1 file changed, 16 deletions(-)
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index bed4308..9e6fa09 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -4810,15 +4810,6 @@ static long ext4_zero_range(struct file *file, loff_t offset,
>  		flags |= EXT4_GET_BLOCKS_KEEP_SIZE;
>  
>  	mutex_lock(&inode->i_mutex);
> -
> -	/*
> -	 * Indirect files do not support unwritten extnets
> -	 */
> -	if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
> -		ret = -EOPNOTSUPP;
> -		goto out_mutex;
> -	}
> -
>  	if (!(mode & FALLOC_FL_KEEP_SIZE) &&
>  	     offset + len > i_size_read(inode)) {
>  		new_size = offset + len;
> @@ -5445,13 +5436,6 @@ int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
>  		ret = -EINVAL;
>  		goto out_mutex;
>  	}
> -
> -	/* Currently just for extent based files */
> -	if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
> -		ret = -EOPNOTSUPP;
> -		goto out_mutex;
> -	}
> -
>  	truncate_pagecache(inode, ioffset);
>  
>  	/* Wait for existing dio to complete */
> -- 
> 2.3.4
>
> --
> 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

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Re: [PATCH] ext4: Remove redundant check under lock scope

[Davide Italiano]

On Tue, Apr 7, 2015 at 3:13 AM, Dmitry Monakhov <dmonlist@gmail.com> wrote:
>
> Davide Italiano <dccitaliano@gmail.com> writes:
>
> > ext4_zero_range() and ext4_collapse_range() duplicate
> > the check in ext4_fallocate(). The checks are made with
> > inode lock held when there's no need for that. Remove them,
> > reducing the scope of the lock.
> NAK. Other task can convert indirect<=>extent via
> ioctl(, EXT4_IOC_SETFLAGS, flags)
>   ->ext4_ext_migrate()
>   ->ext4_int_migrate()
> So we _must_ recheck EXT4_INODE_EXTENTS after we grab i_mutex.
> >
> > Signed-off-by: Davide Italiano <dccitaliano@gmail.com>
> > ---
> >  fs/ext4/extents.c | 16 ----------------
> >  1 file changed, 16 deletions(-)
> >
> > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> > index bed4308..9e6fa09 100644
> > --- a/fs/ext4/extents.c
> > +++ b/fs/ext4/extents.c
> > @@ -4810,15 +4810,6 @@ static long ext4_zero_range(struct file *file, loff_t offset,
> >               flags |= EXT4_GET_BLOCKS_KEEP_SIZE;
> >
> >       mutex_lock(&inode->i_mutex);
> > -
> > -     /*
> > -      * Indirect files do not support unwritten extnets
> > -      */
> > -     if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) {
> > -             ret = -EOPNOTSUPP;
> > -             goto out_mutex;
> > -     }
> > -
> >       if (!(mode & FALLOC_FL_KEEP_SIZE) &&
> >            offset + len > i_size_read(inode)) {
> >               new_size = offset + len;
> > @@ -5445,13 +5436,6 @@ int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len)
> >               ret = -EINVAL;
> >               goto out_mutex;
> >       }
> > -
> > -     /* Currently just for extent based files */
> > -     if (!ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS)) {
> > -             ret = -EOPNOTSUPP;
> > -             goto out_mutex;
> > -     }
> > -
> >       truncate_pagecache(inode, ioffset);
> >
> >       /* Wait for existing dio to complete */
> > --
> > 2.3.4
> >
> > --
> > 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


Thanks, this explains it. Do you think it's worth adding a comment
explaining this behaviour?

--
Davide