Re: [PATCH v2 4/5] btrfs: don't allow -C or +c chattrs on a swap file

[David Sterba]

On Fri, Nov 21, 2014 at 02:08:30AM -0800, Omar Sandoval wrote:
> @@ -293,14 +293,21 @@ static int btrfs_ioctl_setflags(struct file *file, void 
> __user *arg)
>   }
>   } else {

You can put the condition here, instead of shifting the nested block.

} else if (!IS_SWAPFILE(inode)) {

>   /*
> -  * Revert back under same assuptions as above
> +  * swap_activate checks that we don't swapon a copy-on-write
> +  * file, but we must also make sure that it doesn't become
> +  * copy-on-write.
>*/
> - if (S_ISREG(mode)) {
> - if (inode->i_size == 0)
> - ip->flags &= ~(BTRFS_INODE_NODATACOW
> -  | BTRFS_INODE_NODATASUM);
> - } else {
> - ip->flags &= ~BTRFS_INODE_NODATACOW;
> + if (!IS_SWAPFILE(inode)) {
> + /*
> +  * Revert back under same assumptions as above
> +  */
> + if (S_ISREG(mode)) {
> + if (inode->i_size == 0)
> + ip->flags &= ~(BTRFS_INODE_NODATACOW |
> +BTRFS_INODE_NODATASUM);
> + } else {
> + ip->flags &= ~BTRFS_INODE_NODATACOW;
> + }
>   }
>   }
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[PATCH v2 4/5] btrfs: don't allow -C or +c chattrs on a swap file

[Omar Sandoval]

swap_activate will check for a compressed or copy-on-write file; we shouldn't
allow it to become either once it has already been activated.

Signed-off-by: Omar Sandoval 
---
 fs/btrfs/ioctl.c | 50 +++---
 1 file changed, 31 insertions(+), 19 deletions(-)

diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 4399f0c..f022dce 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -293,14 +293,21 @@ static int btrfs_ioctl_setflags(struct file *file, void 
__user *arg)
}
} else {
/*
-* Revert back under same assuptions as above
+* swap_activate checks that we don't swapon a copy-on-write
+* file, but we must also make sure that it doesn't become
+* copy-on-write.
 */
-   if (S_ISREG(mode)) {
-   if (inode->i_size == 0)
-   ip->flags &= ~(BTRFS_INODE_NODATACOW
-| BTRFS_INODE_NODATASUM);
-   } else {
-   ip->flags &= ~BTRFS_INODE_NODATACOW;
+   if (!IS_SWAPFILE(inode)) {
+   /*
+* Revert back under same assumptions as above
+*/
+   if (S_ISREG(mode)) {
+   if (inode->i_size == 0)
+   ip->flags &= ~(BTRFS_INODE_NODATACOW |
+  BTRFS_INODE_NODATASUM);
+   } else {
+   ip->flags &= ~BTRFS_INODE_NODATACOW;
+   }
}
}
 
@@ -317,20 +324,25 @@ static int btrfs_ioctl_setflags(struct file *file, void 
__user *arg)
if (ret && ret != -ENODATA)
goto out_drop;
} else if (flags & FS_COMPR_FL) {
-   const char *comp;
-
-   ip->flags |= BTRFS_INODE_COMPRESS;
-   ip->flags &= ~BTRFS_INODE_NOCOMPRESS;
+   /*
+* Like nodatacow, swap_activate checks that we don't swapon a
+* compressed file, so we shouldn't let it become compressed.
+*/
+   if (!IS_SWAPFILE(inode)) {
+   const char *comp;
 
-   if (root->fs_info->compress_type == BTRFS_COMPRESS_LZO)
-   comp = "lzo";
-   else
-   comp = "zlib";
-   ret = btrfs_set_prop(inode, "btrfs.compression",
-comp, strlen(comp), 0);
-   if (ret)
-   goto out_drop;
+   ip->flags |= BTRFS_INODE_COMPRESS;
+   ip->flags &= ~BTRFS_INODE_NOCOMPRESS;
 
+   if (root->fs_info->compress_type == BTRFS_COMPRESS_LZO)
+   comp = "lzo";
+   else
+   comp = "zlib";
+   ret = btrfs_set_prop(inode, "btrfs.compression",
+comp, strlen(comp), 0);
+   if (ret)
+   goto out_drop;
+   }
} else {
ret = btrfs_set_prop(inode, "btrfs.compression", NULL, 0, 0);
if (ret && ret != -ENODATA)
-- 
2.1.3

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