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The log quiesce mechanism historically terminates by marking the log clean with an unmount record. The primary objective is to indicate that log recovery is no longer required after the quiesce has flushed all in-core changes and written back filesystem metadata. While this is perfectly fine, it is somewhat hacky as currently used in certain contexts. For example, filesystem freeze quiesces (i.e. cleans) the log and immediately redirties it with a dummy superblock transaction to ensure that log recovery runs in the event of a crash. While this functions correctly, cleaning the log from freeze context is clearly superfluous given the current redirtying behavior. Instead, the desired behavior can be achieved by simply covering the log. This effectively retires all on-disk log items from the active range of the log by issuing two synchronous and sequential dummy superblock update transactions that serve to update the on-disk log head and tail. The subtle difference is that the log technically remains dirty due to the lack of an unmount record, though recovery is effectively a no-op due to the content of the checkpoints being clean (i.e. the unmodified on-disk superblock). Log covering currently runs in the background and only triggers once the filesystem and log has idled. The purpose of the background mechanism is to prevent log recovery from replaying the most recently logged items long after those items may have been written back. In the quiesce path, the log has been deliberately idled by forcing the log and pushing the AIL until empty in a context where no further mutable filesystem operations are allowed. Therefore, we can cover the log as the final step in the log quiesce codepath to reflect that all previously active items have been successfully written back. This facilitates selective log covering from certain contexts (i.e. freeze) that only seek to quiesce, but not necessarily clean the log. Note that as a side effect of this change, log covering now occurs when cleaning the log as well. This is harmless, facilitates subsequent cleanups, and is mostly temporary as various operations switch to use explicit log covering. Signed-off-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Signed-off-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Allison Henderson <allison.henderson@oracle.com>
149 lines
4.3 KiB
C
149 lines
4.3 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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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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#ifndef __XFS_LOG_H__
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#define __XFS_LOG_H__
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struct xfs_cil_ctx;
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struct xfs_log_vec {
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struct xfs_log_vec *lv_next; /* next lv in build list */
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int lv_niovecs; /* number of iovecs in lv */
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struct xfs_log_iovec *lv_iovecp; /* iovec array */
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struct xfs_log_item *lv_item; /* owner */
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char *lv_buf; /* formatted buffer */
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int lv_bytes; /* accounted space in buffer */
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int lv_buf_len; /* aligned size of buffer */
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int lv_size; /* size of allocated lv */
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};
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#define XFS_LOG_VEC_ORDERED (-1)
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static inline void *
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xlog_prepare_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec **vecp,
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uint type)
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{
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struct xfs_log_iovec *vec = *vecp;
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if (vec) {
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ASSERT(vec - lv->lv_iovecp < lv->lv_niovecs);
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vec++;
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} else {
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vec = &lv->lv_iovecp[0];
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}
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vec->i_type = type;
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vec->i_addr = lv->lv_buf + lv->lv_buf_len;
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ASSERT(IS_ALIGNED((unsigned long)vec->i_addr, sizeof(uint64_t)));
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*vecp = vec;
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return vec->i_addr;
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}
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/*
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* We need to make sure the next buffer is naturally aligned for the biggest
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* basic data type we put into it. We already accounted for this padding when
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* sizing the buffer.
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*
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* However, this padding does not get written into the log, and hence we have to
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* track the space used by the log vectors separately to prevent log space hangs
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* due to inaccurate accounting (i.e. a leak) of the used log space through the
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* CIL context ticket.
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*/
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static inline void
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xlog_finish_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec *vec, int len)
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{
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lv->lv_buf_len += round_up(len, sizeof(uint64_t));
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lv->lv_bytes += len;
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vec->i_len = len;
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}
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static inline void *
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xlog_copy_iovec(struct xfs_log_vec *lv, struct xfs_log_iovec **vecp,
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uint type, void *data, int len)
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{
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void *buf;
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buf = xlog_prepare_iovec(lv, vecp, type);
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memcpy(buf, data, len);
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xlog_finish_iovec(lv, *vecp, len);
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return buf;
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}
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/*
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* By comparing each component, we don't have to worry about extra
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* endian issues in treating two 32 bit numbers as one 64 bit number
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*/
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static inline xfs_lsn_t _lsn_cmp(xfs_lsn_t lsn1, xfs_lsn_t lsn2)
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{
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if (CYCLE_LSN(lsn1) != CYCLE_LSN(lsn2))
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return (CYCLE_LSN(lsn1)<CYCLE_LSN(lsn2))? -999 : 999;
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if (BLOCK_LSN(lsn1) != BLOCK_LSN(lsn2))
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return (BLOCK_LSN(lsn1)<BLOCK_LSN(lsn2))? -999 : 999;
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return 0;
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}
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#define XFS_LSN_CMP(x,y) _lsn_cmp(x,y)
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/*
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* Flags to xfs_log_force()
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*
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* XFS_LOG_SYNC: Synchronous force in-core log to disk
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*/
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#define XFS_LOG_SYNC 0x1
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/* Log manager interfaces */
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struct xfs_mount;
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struct xlog_in_core;
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struct xlog_ticket;
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struct xfs_log_item;
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struct xfs_item_ops;
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struct xfs_trans;
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int xfs_log_force(struct xfs_mount *mp, uint flags);
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int xfs_log_force_lsn(struct xfs_mount *mp, xfs_lsn_t lsn, uint flags,
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int *log_forced);
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int xfs_log_mount(struct xfs_mount *mp,
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struct xfs_buftarg *log_target,
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xfs_daddr_t start_block,
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int num_bblocks);
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int xfs_log_mount_finish(struct xfs_mount *mp);
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void xfs_log_mount_cancel(struct xfs_mount *);
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xfs_lsn_t xlog_assign_tail_lsn(struct xfs_mount *mp);
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xfs_lsn_t xlog_assign_tail_lsn_locked(struct xfs_mount *mp);
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void xfs_log_space_wake(struct xfs_mount *mp);
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void xfs_log_release_iclog(struct xlog_in_core *iclog);
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int xfs_log_reserve(struct xfs_mount *mp,
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int length,
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int count,
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struct xlog_ticket **ticket,
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uint8_t clientid,
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bool permanent);
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int xfs_log_regrant(struct xfs_mount *mp, struct xlog_ticket *tic);
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void xfs_log_unmount(struct xfs_mount *mp);
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int xfs_log_force_umount(struct xfs_mount *mp, int logerror);
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bool xfs_log_writable(struct xfs_mount *mp);
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struct xlog_ticket *xfs_log_ticket_get(struct xlog_ticket *ticket);
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void xfs_log_ticket_put(struct xlog_ticket *ticket);
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void xfs_log_commit_cil(struct xfs_mount *mp, struct xfs_trans *tp,
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xfs_lsn_t *commit_lsn, bool regrant);
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void xlog_cil_process_committed(struct list_head *list);
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bool xfs_log_item_in_current_chkpt(struct xfs_log_item *lip);
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void xfs_log_work_queue(struct xfs_mount *mp);
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int xfs_log_quiesce(struct xfs_mount *mp);
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void xfs_log_clean(struct xfs_mount *mp);
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bool xfs_log_check_lsn(struct xfs_mount *, xfs_lsn_t);
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bool xfs_log_in_recovery(struct xfs_mount *);
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xfs_lsn_t xlog_grant_push_threshold(struct xlog *log, int need_bytes);
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#endif /* __XFS_LOG_H__ */
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