NTFS: Use i_size_read() in fs/ntfs/logfile.c::ntfs_{check,empty}_logfile().

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

fs/ntfs/ChangeLog

@@ -2,20 +2,18 @@ ToDo/Notes:
 	- Find and fix bugs.
 	- Checkpoint or disable the user space journal ($UsnJrnl).
 	- In between ntfs_prepare/commit_write, need exclusion between
-	  simultaneous file extensions. Need perhaps an NInoResizeUnderway()
-	  flag which we can set in ntfs_prepare_write() and clear again in
-	  ntfs_commit_write(). Just have to be careful in readpage/writepage,
-	  as well as in truncate, that we play nice... We might need to have
-	  a data_size field in the ntfs_inode to store the real attribute
-	  length. Also need to be careful with initialized_size extention in
+	  simultaneous file extensions.  This is given to us by holding i_sem
+	  on the inode.  The only places in the kernel when a file is resized
+	  are prepare/commit write and truncate for both of which i_sem is
+	  held.  Just have to be careful in readpage/writepage and all other
+	  helpers not running under i_sem that we play nice...
+	  Also need to be careful with initialized_size extention in
 	  ntfs_prepare_write. Basically, just be _very_ careful in this code...
-	  OTOH, perhaps i_sem, which is held accross generic_file_write is
-	  sufficient for synchronisation here. We then just need to make sure
-	  ntfs_readpage/writepage/truncate interoperate properly with us.
-	  UPDATE: The above is all ok as it is due to i_sem held.  The only
-	  thing that needs to be checked is ntfs_writepage() which does not
-	  hold i_sem.  It cannot change i_size but it needs to cope with a
-	  concurrent i_size change.
+	  UPDATE: The only things that need to be checked are read/writepage
+	  which do not hold i_sem.  Note writepage cannot change i_size but it
+	  needs to cope with a concurrent i_size change, just like readpage.
+	  Also both need to cope with concurrent changes to the other sizes,
+	  i.e. initialized/allocated/compressed size, as well.
 	- Implement mft.c::sync_mft_mirror_umount().  We currently will just
 	  leave the volume dirty on umount if the final iput(vol->mft_ino)
 	  causes a write of any mirrored mft records due to the mft mirror
@@ -32,6 +30,7 @@ ToDo/Notes:
 	  attack.  Thanks to Carl-Daniel Hailfinger from SuSE for pointing this
 	  out.
 	- Use i_size_read() in fs/ntfs/attrib.c::ntfs_attr_set().
+	- Use i_size_read() in fs/ntfs/logfile.c::ntfs_{check,empty}_logfile().
 
 2.1.22 - Many bug and race fixes and error handling improvements.
 

fs/ntfs/logfile.c

@@ -443,7 +443,7 @@ BOOL ntfs_check_logfile(struct inode *log_vi)
 	/* An empty $LogFile must have been clean before it got emptied. */
 	if (NVolLogFileEmpty(vol))
 		goto is_empty;
-	size = log_vi->i_size;
+	size = i_size_read(log_vi);
 	/* Make sure the file doesn't exceed the maximum allowed size. */
 	if (size > MaxLogFileSize)
 		size = MaxLogFileSize;
@@ -689,7 +689,8 @@ BOOL ntfs_empty_logfile(struct inode *log_vi)
 	if (!NVolLogFileEmpty(vol)) {
 		int err;
 		
-		err = ntfs_attr_set(NTFS_I(log_vi), 0, log_vi->i_size, 0xff);
+		err = ntfs_attr_set(NTFS_I(log_vi), 0, i_size_read(log_vi),
+				0xff);
 		if (unlikely(err)) {
 			ntfs_error(vol->sb, "Failed to fill $LogFile with "
 					"0xff bytes (error code %i).", err);