Merge remote-tracking branch 'origin/upstream-f2fs-stable-linux-4.4.y' into android-4.4

* origin/upstream-f2fs-stable-linux-4.4.y:
  f2fs: use EINVAL for superblock with invalid magic
  f2fs: fix to read source block before invalidating it
  f2fs: remove redundant check from f2fs_setflags_common()
  f2fs: use generic checking and prep function for FS_IOC_SETFLAGS
  f2fs: improve print log in f2fs_sanity_check_ckpt()
  f2fs: avoid out-of-range memory access
  f2fs: fix to avoid long latency during umount
  f2fs: allow all the users to pin a file
  f2fs: support swap file w/ DIO
  f2fs: allocate blocks for pinned file
  f2fs: fix is_idle() check for discard type
  f2fs: add a rw_sem to cover quota flag changes
  f2fs: set SBI_NEED_FSCK for xattr corruption case
  f2fs: use generic EFSBADCRC/EFSCORRUPTED
  f2fs: Use DIV_ROUND_UP() instead of open-coding
  f2fs: print kernel message if filesystem is inconsistent
  f2fs: introduce f2fs_<level> macros to wrap f2fs_printk()
  f2fs: avoid get_valid_blocks() for cleanup
  f2fs: ioctl for removing a range from F2FS
  f2fs: only set project inherit bit for directory
  f2fs: separate f2fs i_flags from fs_flags and ext4 i_flags
  f2fs: Add option to limit required GC for checkpoint=disable
  f2fs: Fix accounting for unusable blocks
  f2fs: Fix root reserved on remount
  f2fs: Lower threshold for disable_cp_again
  f2fs: fix sparse warning
  f2fs: fix f2fs_show_options to show nodiscard mount option
  f2fs: add error prints for debugging mount failure
  f2fs: fix to do sanity check on segment bitmap of LFS curseg
  f2fs: add missing sysfs entries in documentation
  f2fs: fix to avoid deadloop if data_flush is on
  f2fs: always assume that the device is idle under gc_urgent
  f2fs: add bio cache for IPU
  f2fs: allow ssr block allocation during checkpoint=disable period
  f2fs: fix to check layout on last valid checkpoint park

Change-Id: I12033b777edf57fb337c13df82caec464f1426d6
Signed-off-by: Jaegeuk Kim <jaegeuk@google.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/fs/inode.c b/fs/inode.c
index 10015f17b8ea..8e811a0e6be1 100644
--- a/fs/inode.c
+++ b/fs/inode.c
@@ -2052,3 +2052,27 @@ void inode_nohighmem(struct inode *inode)
 	mapping_set_gfp_mask(inode->i_mapping, GFP_USER);
 }
 EXPORT_SYMBOL(inode_nohighmem);
+
+/*
+ * Generic function to check FS_IOC_SETFLAGS values and reject any invalid
+ * configurations.
+ *
+ * Note: the caller should be holding i_mutex, or else be sure that they have
+ * exclusive access to the inode structure.
+ */
+int vfs_ioc_setflags_prepare(struct inode *inode, unsigned int oldflags,
+			     unsigned int flags)
+{
+	/*
+	 * The IMMUTABLE and APPEND_ONLY flags can only be changed by
+	 * the relevant capability.
+	 *
+	 * This test looks nicer. Thanks to Pauline Middelink
+	 */
+	if ((flags ^ oldflags) & (FS_APPEND_FL | FS_IMMUTABLE_FL) &&
+	    !capable(CAP_LINUX_IMMUTABLE))
+		return -EPERM;
+
+	return 0;
+}
+EXPORT_SYMBOL(vfs_ioc_setflags_prepare);