[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 osan...@osandov.com
---
 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

--
To unsubscribe from this list: send the line unsubscribe linux-btrfs in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

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;
 + }
   }
   }
--
To unsubscribe from this list: send the line unsubscribe linux-btrfs in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html