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Subject[PATCH v2 4/5] btrfs: don't allow -C or +c chattrs on a swap file
Date
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 <osandov@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


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