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btrfs: btrfs_permission's RO check shouldn't apply to device nodes 

This patch tightens the read-only access checks in btrfs_permission to
 match the constraints in inode_permission. Currently, even though the
 device node itself will be unmodified, read-write access to device nodes
 is denied to when the device node resides on a read-only subvolume or a
 is a file that has been marked read-only by the btrfs conversion utility.

 With this patch applied, the check only affects regular files,
 directories, and symlinks. It also restructures the code a bit so that
 we don't duplicate the MAY_WRITE check for both tests.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Jeff Mahoney 2011-08-15 17:27:21 +00:00 committed by Chris Mason
parent 93ee7a9340
commit cb6db4e576
1 changed files with 8 additions and 4 deletions
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12
fs/btrfs/inode.c
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@ -7354,11 +7354,15 @@ static int btrfs_set_page_dirty(struct page *page)
static int btrfs_permission(struct inode *inode, int mask)
{
struct btrfs_root *root = BTRFS_I(inode)->root;
umode_t mode = inode->i_mode;
if (btrfs_root_readonly(root) && (mask & MAY_WRITE))
return -EROFS;
if ((BTRFS_I(inode)->flags & BTRFS_INODE_READONLY) && (mask & MAY_WRITE))
return -EACCES;
if (mask & MAY_WRITE &&
(S_ISREG(mode) || S_ISDIR(mode) || S_ISLNK(mode))) {
if (btrfs_root_readonly(root))
return -EROFS;
if (BTRFS_I(inode)->flags & BTRFS_INODE_READONLY)
return -EACCES;
}
return generic_permission(inode, mask);
}