Most filesystems prevent truncation of an active swapfile by way of
inode_newsize_ok, called from inode_change_ok. NFS doesn't call either
from nfs_setattr, presumably because most of these checks are expected
to be done server-side. However, the IS_SWAPFILE check can only be done
client-side, and not doing so is dangerous.
Signed-off-by: Omar Sandoval <osan...@osandov.com>
---
fs/nfs/inode.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 4bffe63..9205513 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -506,10 +506,15 @@ nfs_setattr(struct dentry *dentry, struct iattr *attr)
attr->ia_valid &= ~ATTR_MODE;
if (attr->ia_valid & ATTR_SIZE) {
+ loff_t i_size;
+
BUG_ON(!S_ISREG(inode->i_mode));
- if (attr->ia_size == i_size_read(inode))
+ i_size = i_size_read(inode);
+ if (attr->ia_size == i_size)
attr->ia_valid &= ~ATTR_SIZE;
+ else if (attr->ia_size < i_size && IS_SWAPFILE(inode))
+ return -ETXTBSY;
}
/* Optimization: if the end result is no change, don't RPC */
--
2.2.0
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