4df27c4d5c
btrfs allows subvolumes and snapshots anywhere in the directory tree. If we snapshot a subvolume that contains a link to other subvolume called subvolA, subvolA can be accessed through both the original subvolume and the snapshot. This is similar to creating hard link to directory, and has the very similar problems. The aim of this patch is enforcing there is only one access point to each subvolume. Only the first directory entry (the one added when the subvolume/snapshot was created) is treated as valid access point. The first directory entry is distinguished by checking root forward reference. If the corresponding root forward reference is missing, we know the entry is not the first one. This patch also adds snapshot/subvolume rename support, the code allows rename subvolume link across subvolumes. Signed-off-by: Yan Zheng <zheng.yan@oracle.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
158 lines
4.3 KiB
C
158 lines
4.3 KiB
C
/*
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* Copyright (C) 2007 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#ifndef __BTRFS_I__
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#define __BTRFS_I__
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#include "extent_map.h"
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#include "extent_io.h"
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#include "ordered-data.h"
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/* in memory btrfs inode */
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struct btrfs_inode {
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/* which subvolume this inode belongs to */
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struct btrfs_root *root;
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/* key used to find this inode on disk. This is used by the code
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* to read in roots of subvolumes
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*/
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struct btrfs_key location;
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/* the extent_tree has caches of all the extent mappings to disk */
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struct extent_map_tree extent_tree;
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/* the io_tree does range state (DIRTY, LOCKED etc) */
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struct extent_io_tree io_tree;
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/* special utility tree used to record which mirrors have already been
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* tried when checksums fail for a given block
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*/
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struct extent_io_tree io_failure_tree;
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/* held while inesrting or deleting extents from files */
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struct mutex extent_mutex;
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/* held while logging the inode in tree-log.c */
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struct mutex log_mutex;
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/* used to order data wrt metadata */
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struct btrfs_ordered_inode_tree ordered_tree;
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/* for keeping track of orphaned inodes */
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struct list_head i_orphan;
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/* list of all the delalloc inodes in the FS. There are times we need
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* to write all the delalloc pages to disk, and this list is used
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* to walk them all.
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*/
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struct list_head delalloc_inodes;
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/*
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* list for tracking inodes that must be sent to disk before a
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* rename or truncate commit
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*/
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struct list_head ordered_operations;
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/* node for the red-black tree that links inodes in subvolume root */
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struct rb_node rb_node;
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/* the space_info for where this inode's data allocations are done */
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struct btrfs_space_info *space_info;
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/* full 64 bit generation number, struct vfs_inode doesn't have a big
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* enough field for this.
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*/
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u64 generation;
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/* sequence number for NFS changes */
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u64 sequence;
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/*
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* transid of the trans_handle that last modified this inode
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*/
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u64 last_trans;
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/*
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* transid that last logged this inode
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*/
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u64 logged_trans;
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/* total number of bytes pending delalloc, used by stat to calc the
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* real block usage of the file
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*/
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u64 delalloc_bytes;
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/* total number of bytes that may be used for this inode for
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* delalloc
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*/
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u64 reserved_bytes;
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/*
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* the size of the file stored in the metadata on disk. data=ordered
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* means the in-memory i_size might be larger than the size on disk
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* because not all the blocks are written yet.
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*/
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u64 disk_i_size;
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/* flags field from the on disk inode */
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u32 flags;
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/*
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* if this is a directory then index_cnt is the counter for the index
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* number for new files that are created
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*/
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u64 index_cnt;
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/* the start of block group preferred for allocations. */
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u64 block_group;
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/* the fsync log has some corner cases that mean we have to check
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* directories to see if any unlinks have been done before
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* the directory was logged. See tree-log.c for all the
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* details
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*/
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u64 last_unlink_trans;
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/*
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* ordered_data_close is set by truncate when a file that used
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* to have good data has been truncated to zero. When it is set
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* the btrfs file release call will add this inode to the
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* ordered operations list so that we make sure to flush out any
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* new data the application may have written before commit.
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*
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* yes, its silly to have a single bitflag, but we might grow more
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* of these.
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*/
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unsigned ordered_data_close:1;
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unsigned dummy_inode:1;
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struct inode vfs_inode;
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};
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static inline struct btrfs_inode *BTRFS_I(struct inode *inode)
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{
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return container_of(inode, struct btrfs_inode, vfs_inode);
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}
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static inline void btrfs_i_size_write(struct inode *inode, u64 size)
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{
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inode->i_size = size;
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BTRFS_I(inode)->disk_i_size = size;
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}
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#endif
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