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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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9e351cc862
Lets try this again. We can deadlock the box if we send on a box and try to write onto the same fs with the app that is trying to listen to the send pipe. This is because the writer could get stuck waiting for a transaction commit which is being blocked by the send. So fix this by making sure looking at the commit roots is always going to be consistent. We do this by keeping track of which roots need to have their commit roots swapped during commit, and then taking the commit_root_sem and swapping them all at once. Then make sure we take a read lock on the commit_root_sem in cases where we search the commit root to make sure we're always looking at a consistent view of the commit roots. Previously we had problems with this because we would swap a fs tree commit root and then swap the extent tree commit root independently which would cause the backref walking code to screw up sometimes. With this patch we no longer deadlock and pass all the weird send/receive corner cases. Thanks, Reportedy-by: Hugo Mills <hugo@carfax.org.uk> Signed-off-by: Josef Bacik <jbacik@fb.com> Signed-off-by: Chris Mason <clm@fb.com>
173 lines
5.8 KiB
C
173 lines
5.8 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_TRANSACTION__
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#define __BTRFS_TRANSACTION__
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#include "btrfs_inode.h"
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#include "delayed-ref.h"
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#include "ctree.h"
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enum btrfs_trans_state {
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TRANS_STATE_RUNNING = 0,
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TRANS_STATE_BLOCKED = 1,
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TRANS_STATE_COMMIT_START = 2,
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TRANS_STATE_COMMIT_DOING = 3,
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TRANS_STATE_UNBLOCKED = 4,
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TRANS_STATE_COMPLETED = 5,
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TRANS_STATE_MAX = 6,
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};
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struct btrfs_transaction {
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u64 transid;
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/*
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* total external writers(USERSPACE/START/ATTACH) in this
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* transaction, it must be zero before the transaction is
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* being committed
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*/
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atomic_t num_extwriters;
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/*
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* total writers in this transaction, it must be zero before the
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* transaction can end
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*/
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atomic_t num_writers;
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atomic_t use_count;
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/* Be protected by fs_info->trans_lock when we want to change it. */
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enum btrfs_trans_state state;
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struct list_head list;
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struct extent_io_tree dirty_pages;
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unsigned long start_time;
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wait_queue_head_t writer_wait;
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wait_queue_head_t commit_wait;
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struct list_head pending_snapshots;
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struct list_head ordered_operations;
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struct list_head pending_chunks;
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struct list_head switch_commits;
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struct btrfs_delayed_ref_root delayed_refs;
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int aborted;
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};
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#define __TRANS_FREEZABLE (1U << 0)
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#define __TRANS_USERSPACE (1U << 8)
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#define __TRANS_START (1U << 9)
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#define __TRANS_ATTACH (1U << 10)
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#define __TRANS_JOIN (1U << 11)
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#define __TRANS_JOIN_NOLOCK (1U << 12)
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#define TRANS_USERSPACE (__TRANS_USERSPACE | __TRANS_FREEZABLE)
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#define TRANS_START (__TRANS_START | __TRANS_FREEZABLE)
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#define TRANS_ATTACH (__TRANS_ATTACH)
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#define TRANS_JOIN (__TRANS_JOIN | __TRANS_FREEZABLE)
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#define TRANS_JOIN_NOLOCK (__TRANS_JOIN_NOLOCK)
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#define TRANS_EXTWRITERS (__TRANS_USERSPACE | __TRANS_START | \
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__TRANS_ATTACH)
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#define BTRFS_SEND_TRANS_STUB 1
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struct btrfs_trans_handle {
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u64 transid;
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u64 bytes_reserved;
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u64 qgroup_reserved;
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unsigned long use_count;
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unsigned long blocks_reserved;
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unsigned long blocks_used;
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unsigned long delayed_ref_updates;
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struct btrfs_transaction *transaction;
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struct btrfs_block_rsv *block_rsv;
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struct btrfs_block_rsv *orig_rsv;
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short aborted;
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short adding_csums;
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bool allocating_chunk;
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bool reloc_reserved;
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bool sync;
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unsigned int type;
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/*
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* this root is only needed to validate that the root passed to
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* start_transaction is the same as the one passed to end_transaction.
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* Subvolume quota depends on this
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*/
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struct btrfs_root *root;
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struct seq_list delayed_ref_elem;
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struct list_head qgroup_ref_list;
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struct list_head new_bgs;
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};
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struct btrfs_pending_snapshot {
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struct dentry *dentry;
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struct inode *dir;
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struct btrfs_root *root;
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struct btrfs_root *snap;
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struct btrfs_qgroup_inherit *inherit;
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/* block reservation for the operation */
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struct btrfs_block_rsv block_rsv;
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u64 qgroup_reserved;
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/* extra metadata reseration for relocation */
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int error;
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bool readonly;
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struct list_head list;
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};
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static inline void btrfs_set_inode_last_trans(struct btrfs_trans_handle *trans,
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struct inode *inode)
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{
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BTRFS_I(inode)->last_trans = trans->transaction->transid;
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BTRFS_I(inode)->last_sub_trans = BTRFS_I(inode)->root->log_transid;
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BTRFS_I(inode)->last_log_commit = BTRFS_I(inode)->root->last_log_commit;
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}
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int btrfs_end_transaction(struct btrfs_trans_handle *trans,
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struct btrfs_root *root);
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struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
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int num_items);
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struct btrfs_trans_handle *btrfs_start_transaction_lflush(
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struct btrfs_root *root, int num_items);
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struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root);
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struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root);
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struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root);
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struct btrfs_trans_handle *btrfs_attach_transaction_barrier(
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struct btrfs_root *root);
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struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root);
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int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid);
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int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
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struct btrfs_root *root);
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void btrfs_add_dead_root(struct btrfs_root *root);
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int btrfs_defrag_root(struct btrfs_root *root);
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int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root);
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int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
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struct btrfs_root *root);
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int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
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struct btrfs_root *root,
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int wait_for_unblock);
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int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
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struct btrfs_root *root);
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int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
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struct btrfs_root *root);
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void btrfs_throttle(struct btrfs_root *root);
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int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
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struct btrfs_root *root);
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int btrfs_write_marked_extents(struct btrfs_root *root,
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struct extent_io_tree *dirty_pages, int mark);
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int btrfs_wait_marked_extents(struct btrfs_root *root,
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struct extent_io_tree *dirty_pages, int mark);
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int btrfs_transaction_blocked(struct btrfs_fs_info *info);
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int btrfs_transaction_in_commit(struct btrfs_fs_info *info);
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void btrfs_put_transaction(struct btrfs_transaction *transaction);
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#endif
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