![Josef Bacik](/assets/img/avatar_default.png)
We currently have this problem where you can truncate pages that have not yet been written for an ordered extent. We do this because the truncate will be coming behind to clean us up anyway so what's the harm right? Well if truncate fails for whatever reason we leave an orphan item around for the file to be cleaned up later. But if the user goes and truncates up the file and tries to read from the area that had been discarded previously they will get a csum error because we never actually wrote that data out. This patch fixes this by allowing us to either discard the ordered extent completely, by which I mean we just free up the space we had allocated and not add the file extent, or adjust the length of the file extent we write. We do this by setting the length we truncated down to in the ordered extent, and then we set the file extent length and ram bytes to this length. The total disk space stays unchanged since we may be compressed and we can't just chop off the disk space, but at least this way the file extent only points to the valid data. Then when the file extent is free'd the extent and csums will be freed normally. This patch is needed for the next series which will give us more graceful recovery of failed truncates. Thanks, Signed-off-by: Josef Bacik <jbacik@fusionio.com> Signed-off-by: Chris Mason <chris.mason@fusionio.com>
207 lines
6.6 KiB
C
207 lines
6.6 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_ORDERED_DATA__
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#define __BTRFS_ORDERED_DATA__
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/* one of these per inode */
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struct btrfs_ordered_inode_tree {
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spinlock_t lock;
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struct rb_root tree;
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struct rb_node *last;
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};
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struct btrfs_ordered_sum {
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/* bytenr is the start of this extent on disk */
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u64 bytenr;
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/*
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* this is the length in bytes covered by the sums array below.
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*/
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int len;
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struct list_head list;
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/* last field is a variable length array of csums */
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u32 sums[];
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};
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/*
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* bits for the flags field:
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*
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* BTRFS_ORDERED_IO_DONE is set when all of the blocks are written.
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* It is used to make sure metadata is inserted into the tree only once
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* per extent.
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*
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* BTRFS_ORDERED_COMPLETE is set when the extent is removed from the
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* rbtree, just before waking any waiters. It is used to indicate the
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* IO is done and any metadata is inserted into the tree.
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*/
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#define BTRFS_ORDERED_IO_DONE 0 /* set when all the pages are written */
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#define BTRFS_ORDERED_COMPLETE 1 /* set when removed from the tree */
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#define BTRFS_ORDERED_NOCOW 2 /* set when we want to write in place */
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#define BTRFS_ORDERED_COMPRESSED 3 /* writing a zlib compressed extent */
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#define BTRFS_ORDERED_PREALLOC 4 /* set when writing to prealloced extent */
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#define BTRFS_ORDERED_DIRECT 5 /* set when we're doing DIO with this extent */
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#define BTRFS_ORDERED_IOERR 6 /* We had an io error when writing this out */
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#define BTRFS_ORDERED_UPDATED_ISIZE 7 /* indicates whether this ordered extent
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* has done its due diligence in updating
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* the isize. */
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#define BTRFS_ORDERED_LOGGED_CSUM 8 /* We've logged the csums on this ordered
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ordered extent */
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#define BTRFS_ORDERED_TRUNCATED 9 /* Set when we have to truncate an extent */
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struct btrfs_ordered_extent {
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/* logical offset in the file */
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u64 file_offset;
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/* disk byte number */
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u64 start;
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/* ram length of the extent in bytes */
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u64 len;
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/* extent length on disk */
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u64 disk_len;
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/* number of bytes that still need writing */
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u64 bytes_left;
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/* number of bytes that still need csumming */
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u64 csum_bytes_left;
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/*
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* the end of the ordered extent which is behind it but
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* didn't update disk_i_size. Please see the comment of
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* btrfs_ordered_update_i_size();
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*/
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u64 outstanding_isize;
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/*
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* If we get truncated we need to adjust the file extent we enter for
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* this ordered extent so that we do not expose stale data.
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*/
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u64 truncated_len;
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/* flags (described above) */
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unsigned long flags;
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/* compression algorithm */
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int compress_type;
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/* reference count */
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atomic_t refs;
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/* the inode we belong to */
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struct inode *inode;
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/* list of checksums for insertion when the extent io is done */
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struct list_head list;
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/* If we need to wait on this to be done */
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struct list_head log_list;
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/* used to wait for the BTRFS_ORDERED_COMPLETE bit */
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wait_queue_head_t wait;
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/* our friendly rbtree entry */
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struct rb_node rb_node;
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/* a per root list of all the pending ordered extents */
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struct list_head root_extent_list;
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struct btrfs_work work;
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struct completion completion;
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struct btrfs_work flush_work;
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struct list_head work_list;
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};
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/*
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* calculates the total size you need to allocate for an ordered sum
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* structure spanning 'bytes' in the file
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*/
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static inline int btrfs_ordered_sum_size(struct btrfs_root *root,
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unsigned long bytes)
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{
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int num_sectors = (int)DIV_ROUND_UP(bytes, root->sectorsize);
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return sizeof(struct btrfs_ordered_sum) + num_sectors * sizeof(u32);
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}
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static inline void
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btrfs_ordered_inode_tree_init(struct btrfs_ordered_inode_tree *t)
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{
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spin_lock_init(&t->lock);
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t->tree = RB_ROOT;
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t->last = NULL;
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}
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void btrfs_put_ordered_extent(struct btrfs_ordered_extent *entry);
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void btrfs_remove_ordered_extent(struct inode *inode,
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struct btrfs_ordered_extent *entry);
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int btrfs_dec_test_ordered_pending(struct inode *inode,
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struct btrfs_ordered_extent **cached,
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u64 file_offset, u64 io_size, int uptodate);
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int btrfs_dec_test_first_ordered_pending(struct inode *inode,
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struct btrfs_ordered_extent **cached,
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u64 *file_offset, u64 io_size,
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int uptodate);
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int btrfs_add_ordered_extent(struct inode *inode, u64 file_offset,
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u64 start, u64 len, u64 disk_len, int type);
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int btrfs_add_ordered_extent_dio(struct inode *inode, u64 file_offset,
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u64 start, u64 len, u64 disk_len, int type);
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int btrfs_add_ordered_extent_compress(struct inode *inode, u64 file_offset,
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u64 start, u64 len, u64 disk_len,
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int type, int compress_type);
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void btrfs_add_ordered_sum(struct inode *inode,
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struct btrfs_ordered_extent *entry,
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struct btrfs_ordered_sum *sum);
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struct btrfs_ordered_extent *btrfs_lookup_ordered_extent(struct inode *inode,
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u64 file_offset);
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void btrfs_start_ordered_extent(struct inode *inode,
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struct btrfs_ordered_extent *entry, int wait);
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void btrfs_wait_ordered_range(struct inode *inode, u64 start, u64 len);
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struct btrfs_ordered_extent *
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btrfs_lookup_first_ordered_extent(struct inode * inode, u64 file_offset);
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struct btrfs_ordered_extent *btrfs_lookup_ordered_range(struct inode *inode,
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u64 file_offset,
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u64 len);
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int btrfs_ordered_update_i_size(struct inode *inode, u64 offset,
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struct btrfs_ordered_extent *ordered);
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int btrfs_find_ordered_sum(struct inode *inode, u64 offset, u64 disk_bytenr,
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u32 *sum, int len);
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int btrfs_run_ordered_operations(struct btrfs_trans_handle *trans,
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struct btrfs_root *root, int wait);
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void btrfs_add_ordered_operation(struct btrfs_trans_handle *trans,
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struct btrfs_root *root,
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struct inode *inode);
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void btrfs_wait_ordered_extents(struct btrfs_root *root, int delay_iput);
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void btrfs_wait_all_ordered_extents(struct btrfs_fs_info *fs_info,
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int delay_iput);
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void btrfs_get_logged_extents(struct btrfs_root *log, struct inode *inode);
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void btrfs_wait_logged_extents(struct btrfs_root *log, u64 transid);
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void btrfs_free_logged_extents(struct btrfs_root *log, u64 transid);
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int __init ordered_data_init(void);
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void ordered_data_exit(void);
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#endif
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