On 2010-01-20, at 02:03, Aneesh Kumar K. V wrote:
@@ -4741,8 +4743,8 @@ void ext4_get_inode_flags(struct ext4_inode_info *ei){ unsigned int flags = ei->vfs_inode.i_flags; - ei->i_flags &= ~(EXT4_SYNC_FL|EXT4_APPEND_FL| - EXT4_IMMUTABLE_FL|EXT4_NOATIME_FL|EXT4_DIRSYNC_FL); + ei->i_flags &= ~(EXT4_SYNC_FL|EXT4_APPEND_FL|EXT4_IMMUTABLE_FL| + EXT4_NOATIME_FL|EXT4_DIRSYNC_FL|EXT4_EOFBLOCKS_FL);Do we really need to allow the get and set of this flag. IMHO a truncate should be the only API and the flag should be remove implicitly for that.
Since this flag is set on disk in the inode flags, it makes sense to allow clearing it via "chattr", just like "chattr +e" will remap a file to extent format. The risk with setting it via truncate() is that this is racy with some other process writing to the file. If we allow setting it via "chattr" this can be done in a non-racy manner, by locking the inode and dropping only the blocks beyond EOF.
@@ -92,6 +92,16 @@ long ext4_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)flags &= ~EXT4_EXTENTS_FL; } + if (flags & EXT4_EOFBLOCKS_FL) { + /* we don't support adding EOFBLOCKS flag */ + if (!(oldflags & EXT4_EOFBLOCKS_FL)) { + err = -EOPNOTSUPP; + goto flags_out; + } + } else if (oldflags & EXT4_EOFBLOCKS_FL) + /* free the space reserved with fallocate KEEPSIZE */ + vmtruncate(inode, inode->i_size); + handle = ext4_journal_start(inode, 1); if (IS_ERR(handle)) { err = PTR_ERR(handle);If we remove ext4_ioctl support i guess that patch can become much simpler.
Sure it will be simpler, but less useful. The point of exposing this flag via lsattr is to allow userspace to determine which files are holding blocks beyond EOF, so that if the filesystem is getting too full it is possible to run e.g. "lsattr -R" and find files with this EOF attribute and truncate them. Without keeping at least the EOFBLOCKS flag in USER_VISIBLE this is impossible.
Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
