619 строки
22 KiB
C
619 строки
22 KiB
C
/*
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* Copyright (c) 2000-2003,2005 Silicon Graphics, Inc.
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* 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 License as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it would 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
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* GNU 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 License
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* along with this program; if not, write the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef __XFS_LOG_PRIV_H__
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#define __XFS_LOG_PRIV_H__
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struct xfs_buf;
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struct xlog;
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struct xlog_ticket;
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struct xfs_mount;
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struct xfs_log_callback;
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/*
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* Flags for log structure
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*/
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#define XLOG_ACTIVE_RECOVERY 0x2 /* in the middle of recovery */
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#define XLOG_RECOVERY_NEEDED 0x4 /* log was recovered */
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#define XLOG_IO_ERROR 0x8 /* log hit an I/O error, and being
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shutdown */
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#define XLOG_TAIL_WARN 0x10 /* log tail verify warning issued */
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/*
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* get client id from packed copy.
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*
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* this hack is here because the xlog_pack code copies four bytes
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* of xlog_op_header containing the fields oh_clientid, oh_flags
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* and oh_res2 into the packed copy.
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*
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* later on this four byte chunk is treated as an int and the
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* client id is pulled out.
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*
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* this has endian issues, of course.
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*/
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static inline uint xlog_get_client_id(__be32 i)
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{
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return be32_to_cpu(i) >> 24;
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}
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/*
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* In core log state
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*/
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#define XLOG_STATE_ACTIVE 0x0001 /* Current IC log being written to */
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#define XLOG_STATE_WANT_SYNC 0x0002 /* Want to sync this iclog; no more writes */
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#define XLOG_STATE_SYNCING 0x0004 /* This IC log is syncing */
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#define XLOG_STATE_DONE_SYNC 0x0008 /* Done syncing to disk */
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#define XLOG_STATE_DO_CALLBACK \
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0x0010 /* Process callback functions */
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#define XLOG_STATE_CALLBACK 0x0020 /* Callback functions now */
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#define XLOG_STATE_DIRTY 0x0040 /* Dirty IC log, not ready for ACTIVE status*/
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#define XLOG_STATE_IOERROR 0x0080 /* IO error happened in sync'ing log */
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#define XLOG_STATE_IOABORT 0x0100 /* force abort on I/O completion (debug) */
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#define XLOG_STATE_ALL 0x7FFF /* All possible valid flags */
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#define XLOG_STATE_NOTUSED 0x8000 /* This IC log not being used */
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/*
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* Flags to log ticket
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*/
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#define XLOG_TIC_INITED 0x1 /* has been initialized */
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#define XLOG_TIC_PERM_RESERV 0x2 /* permanent reservation */
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#define XLOG_TIC_FLAGS \
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{ XLOG_TIC_INITED, "XLOG_TIC_INITED" }, \
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{ XLOG_TIC_PERM_RESERV, "XLOG_TIC_PERM_RESERV" }
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/*
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* Below are states for covering allocation transactions.
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* By covering, we mean changing the h_tail_lsn in the last on-disk
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* log write such that no allocation transactions will be re-done during
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* recovery after a system crash. Recovery starts at the last on-disk
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* log write.
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*
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* These states are used to insert dummy log entries to cover
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* space allocation transactions which can undo non-transactional changes
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* after a crash. Writes to a file with space
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* already allocated do not result in any transactions. Allocations
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* might include space beyond the EOF. So if we just push the EOF a
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* little, the last transaction for the file could contain the wrong
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* size. If there is no file system activity, after an allocation
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* transaction, and the system crashes, the allocation transaction
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* will get replayed and the file will be truncated. This could
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* be hours/days/... after the allocation occurred.
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*
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* The fix for this is to do two dummy transactions when the
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* system is idle. We need two dummy transaction because the h_tail_lsn
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* in the log record header needs to point beyond the last possible
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* non-dummy transaction. The first dummy changes the h_tail_lsn to
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* the first transaction before the dummy. The second dummy causes
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* h_tail_lsn to point to the first dummy. Recovery starts at h_tail_lsn.
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*
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* These dummy transactions get committed when everything
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* is idle (after there has been some activity).
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*
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* There are 5 states used to control this.
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*
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* IDLE -- no logging has been done on the file system or
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* we are done covering previous transactions.
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* NEED -- logging has occurred and we need a dummy transaction
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* when the log becomes idle.
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* DONE -- we were in the NEED state and have committed a dummy
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* transaction.
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* NEED2 -- we detected that a dummy transaction has gone to the
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* on disk log with no other transactions.
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* DONE2 -- we committed a dummy transaction when in the NEED2 state.
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*
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* There are two places where we switch states:
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*
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* 1.) In xfs_sync, when we detect an idle log and are in NEED or NEED2.
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* We commit the dummy transaction and switch to DONE or DONE2,
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* respectively. In all other states, we don't do anything.
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*
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* 2.) When we finish writing the on-disk log (xlog_state_clean_log).
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*
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* No matter what state we are in, if this isn't the dummy
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* transaction going out, the next state is NEED.
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* So, if we aren't in the DONE or DONE2 states, the next state
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* is NEED. We can't be finishing a write of the dummy record
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* unless it was committed and the state switched to DONE or DONE2.
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*
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* If we are in the DONE state and this was a write of the
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* dummy transaction, we move to NEED2.
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*
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* If we are in the DONE2 state and this was a write of the
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* dummy transaction, we move to IDLE.
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*
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*
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* Writing only one dummy transaction can get appended to
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* one file space allocation. When this happens, the log recovery
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* code replays the space allocation and a file could be truncated.
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* This is why we have the NEED2 and DONE2 states before going idle.
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*/
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#define XLOG_STATE_COVER_IDLE 0
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#define XLOG_STATE_COVER_NEED 1
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#define XLOG_STATE_COVER_DONE 2
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#define XLOG_STATE_COVER_NEED2 3
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#define XLOG_STATE_COVER_DONE2 4
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#define XLOG_COVER_OPS 5
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/* Ticket reservation region accounting */
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#define XLOG_TIC_LEN_MAX 15
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/*
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* Reservation region
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* As would be stored in xfs_log_iovec but without the i_addr which
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* we don't care about.
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*/
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typedef struct xlog_res {
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uint r_len; /* region length :4 */
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uint r_type; /* region's transaction type :4 */
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} xlog_res_t;
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typedef struct xlog_ticket {
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struct list_head t_queue; /* reserve/write queue */
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struct task_struct *t_task; /* task that owns this ticket */
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xlog_tid_t t_tid; /* transaction identifier : 4 */
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atomic_t t_ref; /* ticket reference count : 4 */
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int t_curr_res; /* current reservation in bytes : 4 */
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int t_unit_res; /* unit reservation in bytes : 4 */
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char t_ocnt; /* original count : 1 */
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char t_cnt; /* current count : 1 */
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char t_clientid; /* who does this belong to; : 1 */
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char t_flags; /* properties of reservation : 1 */
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/* reservation array fields */
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uint t_res_num; /* num in array : 4 */
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uint t_res_num_ophdrs; /* num op hdrs : 4 */
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uint t_res_arr_sum; /* array sum : 4 */
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uint t_res_o_flow; /* sum overflow : 4 */
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xlog_res_t t_res_arr[XLOG_TIC_LEN_MAX]; /* array of res : 8 * 15 */
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} xlog_ticket_t;
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/*
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* - A log record header is 512 bytes. There is plenty of room to grow the
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* xlog_rec_header_t into the reserved space.
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* - ic_data follows, so a write to disk can start at the beginning of
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* the iclog.
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* - ic_forcewait is used to implement synchronous forcing of the iclog to disk.
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* - ic_next is the pointer to the next iclog in the ring.
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* - ic_bp is a pointer to the buffer used to write this incore log to disk.
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* - ic_log is a pointer back to the global log structure.
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* - ic_callback is a linked list of callback function/argument pairs to be
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* called after an iclog finishes writing.
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* - ic_size is the full size of the header plus data.
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* - ic_offset is the current number of bytes written to in this iclog.
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* - ic_refcnt is bumped when someone is writing to the log.
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* - ic_state is the state of the iclog.
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*
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* Because of cacheline contention on large machines, we need to separate
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* various resources onto different cachelines. To start with, make the
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* structure cacheline aligned. The following fields can be contended on
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* by independent processes:
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*
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* - ic_callback_*
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* - ic_refcnt
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* - fields protected by the global l_icloglock
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*
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* so we need to ensure that these fields are located in separate cachelines.
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* We'll put all the read-only and l_icloglock fields in the first cacheline,
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* and move everything else out to subsequent cachelines.
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*/
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typedef struct xlog_in_core {
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wait_queue_head_t ic_force_wait;
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wait_queue_head_t ic_write_wait;
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struct xlog_in_core *ic_next;
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struct xlog_in_core *ic_prev;
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struct xfs_buf *ic_bp;
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struct xlog *ic_log;
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int ic_size;
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int ic_offset;
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int ic_bwritecnt;
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unsigned short ic_state;
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char *ic_datap; /* pointer to iclog data */
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/* Callback structures need their own cacheline */
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spinlock_t ic_callback_lock ____cacheline_aligned_in_smp;
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struct xfs_log_callback *ic_callback;
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struct xfs_log_callback **ic_callback_tail;
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/* reference counts need their own cacheline */
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atomic_t ic_refcnt ____cacheline_aligned_in_smp;
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xlog_in_core_2_t *ic_data;
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#define ic_header ic_data->hic_header
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} xlog_in_core_t;
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/*
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* The CIL context is used to aggregate per-transaction details as well be
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* passed to the iclog for checkpoint post-commit processing. After being
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* passed to the iclog, another context needs to be allocated for tracking the
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* next set of transactions to be aggregated into a checkpoint.
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*/
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struct xfs_cil;
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struct xfs_cil_ctx {
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struct xfs_cil *cil;
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xfs_lsn_t sequence; /* chkpt sequence # */
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xfs_lsn_t start_lsn; /* first LSN of chkpt commit */
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xfs_lsn_t commit_lsn; /* chkpt commit record lsn */
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struct xlog_ticket *ticket; /* chkpt ticket */
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int nvecs; /* number of regions */
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int space_used; /* aggregate size of regions */
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struct list_head busy_extents; /* busy extents in chkpt */
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struct xfs_log_vec *lv_chain; /* logvecs being pushed */
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struct xfs_log_callback log_cb; /* completion callback hook. */
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struct list_head committing; /* ctx committing list */
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struct work_struct discard_endio_work;
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};
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/*
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* Committed Item List structure
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*
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* This structure is used to track log items that have been committed but not
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* yet written into the log. It is used only when the delayed logging mount
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* option is enabled.
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*
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* This structure tracks the list of committing checkpoint contexts so
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* we can avoid the problem of having to hold out new transactions during a
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* flush until we have a the commit record LSN of the checkpoint. We can
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* traverse the list of committing contexts in xlog_cil_push_lsn() to find a
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* sequence match and extract the commit LSN directly from there. If the
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* checkpoint is still in the process of committing, we can block waiting for
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* the commit LSN to be determined as well. This should make synchronous
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* operations almost as efficient as the old logging methods.
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*/
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struct xfs_cil {
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struct xlog *xc_log;
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struct list_head xc_cil;
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spinlock_t xc_cil_lock;
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struct rw_semaphore xc_ctx_lock ____cacheline_aligned_in_smp;
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struct xfs_cil_ctx *xc_ctx;
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spinlock_t xc_push_lock ____cacheline_aligned_in_smp;
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xfs_lsn_t xc_push_seq;
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struct list_head xc_committing;
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wait_queue_head_t xc_commit_wait;
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xfs_lsn_t xc_current_sequence;
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struct work_struct xc_push_work;
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} ____cacheline_aligned_in_smp;
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/*
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* The amount of log space we allow the CIL to aggregate is difficult to size.
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* Whatever we choose, we have to make sure we can get a reservation for the
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* log space effectively, that it is large enough to capture sufficient
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* relogging to reduce log buffer IO significantly, but it is not too large for
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* the log or induces too much latency when writing out through the iclogs. We
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* track both space consumed and the number of vectors in the checkpoint
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* context, so we need to decide which to use for limiting.
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*
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* Every log buffer we write out during a push needs a header reserved, which
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* is at least one sector and more for v2 logs. Hence we need a reservation of
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* at least 512 bytes per 32k of log space just for the LR headers. That means
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* 16KB of reservation per megabyte of delayed logging space we will consume,
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* plus various headers. The number of headers will vary based on the num of
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* io vectors, so limiting on a specific number of vectors is going to result
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* in transactions of varying size. IOWs, it is more consistent to track and
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* limit space consumed in the log rather than by the number of objects being
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* logged in order to prevent checkpoint ticket overruns.
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*
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* Further, use of static reservations through the log grant mechanism is
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* problematic. It introduces a lot of complexity (e.g. reserve grant vs write
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* grant) and a significant deadlock potential because regranting write space
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* can block on log pushes. Hence if we have to regrant log space during a log
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* push, we can deadlock.
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*
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* However, we can avoid this by use of a dynamic "reservation stealing"
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* technique during transaction commit whereby unused reservation space in the
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* transaction ticket is transferred to the CIL ctx commit ticket to cover the
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* space needed by the checkpoint transaction. This means that we never need to
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* specifically reserve space for the CIL checkpoint transaction, nor do we
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* need to regrant space once the checkpoint completes. This also means the
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* checkpoint transaction ticket is specific to the checkpoint context, rather
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* than the CIL itself.
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*
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* With dynamic reservations, we can effectively make up arbitrary limits for
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* the checkpoint size so long as they don't violate any other size rules.
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* Recovery imposes a rule that no transaction exceed half the log, so we are
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* limited by that. Furthermore, the log transaction reservation subsystem
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* tries to keep 25% of the log free, so we need to keep below that limit or we
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* risk running out of free log space to start any new transactions.
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*
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* In order to keep background CIL push efficient, we will set a lower
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* threshold at which background pushing is attempted without blocking current
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* transaction commits. A separate, higher bound defines when CIL pushes are
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* enforced to ensure we stay within our maximum checkpoint size bounds.
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* threshold, yet give us plenty of space for aggregation on large logs.
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*/
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#define XLOG_CIL_SPACE_LIMIT(log) (log->l_logsize >> 3)
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/*
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* ticket grant locks, queues and accounting have their own cachlines
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* as these are quite hot and can be operated on concurrently.
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*/
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struct xlog_grant_head {
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spinlock_t lock ____cacheline_aligned_in_smp;
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struct list_head waiters;
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atomic64_t grant;
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};
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/*
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* The reservation head lsn is not made up of a cycle number and block number.
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* Instead, it uses a cycle number and byte number. Logs don't expect to
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* overflow 31 bits worth of byte offset, so using a byte number will mean
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* that round off problems won't occur when releasing partial reservations.
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*/
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struct xlog {
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/* The following fields don't need locking */
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struct xfs_mount *l_mp; /* mount point */
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struct xfs_ail *l_ailp; /* AIL log is working with */
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struct xfs_cil *l_cilp; /* CIL log is working with */
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struct xfs_buf *l_xbuf; /* extra buffer for log
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* wrapping */
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struct xfs_buftarg *l_targ; /* buftarg of log */
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struct delayed_work l_work; /* background flush work */
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uint l_flags;
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uint l_quotaoffs_flag; /* XFS_DQ_*, for QUOTAOFFs */
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struct list_head *l_buf_cancel_table;
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int l_iclog_hsize; /* size of iclog header */
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int l_iclog_heads; /* # of iclog header sectors */
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uint l_sectBBsize; /* sector size in BBs (2^n) */
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int l_iclog_size; /* size of log in bytes */
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int l_iclog_size_log; /* log power size of log */
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int l_iclog_bufs; /* number of iclog buffers */
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xfs_daddr_t l_logBBstart; /* start block of log */
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int l_logsize; /* size of log in bytes */
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int l_logBBsize; /* size of log in BB chunks */
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/* The following block of fields are changed while holding icloglock */
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wait_queue_head_t l_flush_wait ____cacheline_aligned_in_smp;
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/* waiting for iclog flush */
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int l_covered_state;/* state of "covering disk
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* log entries" */
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xlog_in_core_t *l_iclog; /* head log queue */
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spinlock_t l_icloglock; /* grab to change iclog state */
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int l_curr_cycle; /* Cycle number of log writes */
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int l_prev_cycle; /* Cycle number before last
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* block increment */
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int l_curr_block; /* current logical log block */
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int l_prev_block; /* previous logical log block */
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/*
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* l_last_sync_lsn and l_tail_lsn are atomics so they can be set and
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* read without needing to hold specific locks. To avoid operations
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* contending with other hot objects, place each of them on a separate
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* cacheline.
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*/
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/* lsn of last LR on disk */
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atomic64_t l_last_sync_lsn ____cacheline_aligned_in_smp;
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/* lsn of 1st LR with unflushed * buffers */
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atomic64_t l_tail_lsn ____cacheline_aligned_in_smp;
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struct xlog_grant_head l_reserve_head;
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struct xlog_grant_head l_write_head;
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struct xfs_kobj l_kobj;
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/* The following field are used for debugging; need to hold icloglock */
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#ifdef DEBUG
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void *l_iclog_bak[XLOG_MAX_ICLOGS];
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/* log record crc error injection factor */
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uint32_t l_badcrc_factor;
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#endif
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/* log recovery lsn tracking (for buffer submission */
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xfs_lsn_t l_recovery_lsn;
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};
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#define XLOG_BUF_CANCEL_BUCKET(log, blkno) \
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((log)->l_buf_cancel_table + ((__uint64_t)blkno % XLOG_BC_TABLE_SIZE))
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#define XLOG_FORCED_SHUTDOWN(log) ((log)->l_flags & XLOG_IO_ERROR)
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/* common routines */
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extern int
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xlog_recover(
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struct xlog *log);
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extern int
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xlog_recover_finish(
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struct xlog *log);
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extern int
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xlog_recover_cancel(struct xlog *);
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extern __le32 xlog_cksum(struct xlog *log, struct xlog_rec_header *rhead,
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char *dp, int size);
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extern kmem_zone_t *xfs_log_ticket_zone;
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struct xlog_ticket *
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xlog_ticket_alloc(
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struct xlog *log,
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int unit_bytes,
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int count,
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char client,
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bool permanent,
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xfs_km_flags_t alloc_flags);
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static inline void
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xlog_write_adv_cnt(void **ptr, int *len, int *off, size_t bytes)
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{
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*ptr += bytes;
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*len -= bytes;
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*off += bytes;
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}
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void xlog_print_tic_res(struct xfs_mount *mp, struct xlog_ticket *ticket);
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int
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xlog_write(
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struct xlog *log,
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struct xfs_log_vec *log_vector,
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struct xlog_ticket *tic,
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xfs_lsn_t *start_lsn,
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struct xlog_in_core **commit_iclog,
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uint flags);
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/*
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* When we crack an atomic LSN, we sample it first so that the value will not
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* change while we are cracking it into the component values. This means we
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* will always get consistent component values to work from. This should always
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* be used to sample and crack LSNs that are stored and updated in atomic
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* variables.
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*/
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static inline void
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xlog_crack_atomic_lsn(atomic64_t *lsn, uint *cycle, uint *block)
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{
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xfs_lsn_t val = atomic64_read(lsn);
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*cycle = CYCLE_LSN(val);
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*block = BLOCK_LSN(val);
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}
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/*
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* Calculate and assign a value to an atomic LSN variable from component pieces.
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*/
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static inline void
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xlog_assign_atomic_lsn(atomic64_t *lsn, uint cycle, uint block)
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{
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atomic64_set(lsn, xlog_assign_lsn(cycle, block));
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}
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/*
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* When we crack the grant head, we sample it first so that the value will not
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* change while we are cracking it into the component values. This means we
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* will always get consistent component values to work from.
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*/
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static inline void
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xlog_crack_grant_head_val(int64_t val, int *cycle, int *space)
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{
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*cycle = val >> 32;
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*space = val & 0xffffffff;
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}
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static inline void
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xlog_crack_grant_head(atomic64_t *head, int *cycle, int *space)
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{
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xlog_crack_grant_head_val(atomic64_read(head), cycle, space);
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}
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static inline int64_t
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xlog_assign_grant_head_val(int cycle, int space)
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{
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return ((int64_t)cycle << 32) | space;
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}
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static inline void
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xlog_assign_grant_head(atomic64_t *head, int cycle, int space)
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{
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atomic64_set(head, xlog_assign_grant_head_val(cycle, space));
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}
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/*
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* Committed Item List interfaces
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*/
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int xlog_cil_init(struct xlog *log);
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void xlog_cil_init_post_recovery(struct xlog *log);
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void xlog_cil_destroy(struct xlog *log);
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bool xlog_cil_empty(struct xlog *log);
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/*
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* CIL force routines
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*/
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xfs_lsn_t
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xlog_cil_force_lsn(
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struct xlog *log,
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xfs_lsn_t sequence);
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static inline void
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xlog_cil_force(struct xlog *log)
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{
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xlog_cil_force_lsn(log, log->l_cilp->xc_current_sequence);
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}
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/*
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* Unmount record type is used as a pseudo transaction type for the ticket.
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* It's value must be outside the range of XFS_TRANS_* values.
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*/
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#define XLOG_UNMOUNT_REC_TYPE (-1U)
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/*
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* Wrapper function for waiting on a wait queue serialised against wakeups
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* by a spinlock. This matches the semantics of all the wait queues used in the
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* log code.
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*/
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static inline void xlog_wait(wait_queue_head_t *wq, spinlock_t *lock)
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{
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DECLARE_WAITQUEUE(wait, current);
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add_wait_queue_exclusive(wq, &wait);
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__set_current_state(TASK_UNINTERRUPTIBLE);
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spin_unlock(lock);
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schedule();
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remove_wait_queue(wq, &wait);
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}
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/*
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* The LSN is valid so long as it is behind the current LSN. If it isn't, this
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* means that the next log record that includes this metadata could have a
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* smaller LSN. In turn, this means that the modification in the log would not
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* replay.
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*/
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static inline bool
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xlog_valid_lsn(
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struct xlog *log,
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xfs_lsn_t lsn)
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{
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int cur_cycle;
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int cur_block;
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bool valid = true;
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/*
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* First, sample the current lsn without locking to avoid added
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* contention from metadata I/O. The current cycle and block are updated
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* (in xlog_state_switch_iclogs()) and read here in a particular order
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* to avoid false negatives (e.g., thinking the metadata LSN is valid
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* when it is not).
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*
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* The current block is always rewound before the cycle is bumped in
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* xlog_state_switch_iclogs() to ensure the current LSN is never seen in
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* a transiently forward state. Instead, we can see the LSN in a
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* transiently behind state if we happen to race with a cycle wrap.
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*/
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cur_cycle = ACCESS_ONCE(log->l_curr_cycle);
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smp_rmb();
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cur_block = ACCESS_ONCE(log->l_curr_block);
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if ((CYCLE_LSN(lsn) > cur_cycle) ||
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(CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block)) {
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/*
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* If the metadata LSN appears invalid, it's possible the check
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* above raced with a wrap to the next log cycle. Grab the lock
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* to check for sure.
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*/
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spin_lock(&log->l_icloglock);
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cur_cycle = log->l_curr_cycle;
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cur_block = log->l_curr_block;
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spin_unlock(&log->l_icloglock);
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if ((CYCLE_LSN(lsn) > cur_cycle) ||
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(CYCLE_LSN(lsn) == cur_cycle && BLOCK_LSN(lsn) > cur_block))
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valid = false;
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}
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return valid;
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}
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#endif /* __XFS_LOG_PRIV_H__ */
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