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![Dave Chinner](/assets/img/avatar_default.png)
In doing an investigation into AIL push stalls, I was looking at the log force code to see if an async CIL push could be done instead. This lead me to xfs_log_force_lsn() and looking at how it works. xfs_log_force_lsn() is only called from inode synchronisation contexts such as fsync(), and it takes the ip->i_itemp->ili_last_lsn value as the LSN to sync the log to. This gets passed to xlog_cil_force_lsn() via xfs_log_force_lsn() to flush the CIL to the journal, and then used by xfs_log_force_lsn() to flush the iclogs to the journal. The problem is that ip->i_itemp->ili_last_lsn does not store a log sequence number. What it stores is passed to it from the ->iop_committing method, which is called by xfs_log_commit_cil(). The value this passes to the iop_committing method is the CIL context sequence number that the item was committed to. As it turns out, xlog_cil_force_lsn() converts the sequence to an actual commit LSN for the related context and returns that to xfs_log_force_lsn(). xfs_log_force_lsn() overwrites it's "lsn" variable that contained a sequence with an actual LSN and then uses that to sync the iclogs. This caused me some confusion for a while, even though I originally wrote all this code a decade ago. ->iop_committing is only used by a couple of log item types, and only inode items use the sequence number it is passed. Let's clean up the API, CIL structures and inode log item to call it a sequence number, and make it clear that the high level code is using CIL sequence numbers and not on-disk LSNs for integrity synchronisation purposes. Signed-off-by: Dave Chinner <dchinner@redhat.com> Reviewed-by: Brian Foster <bfoster@redhat.com> Reviewed-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Allison Henderson <allison.henderson@oracle.com> Signed-off-by: Darrick J. Wong <djwong@kernel.org>
52 lines
1.8 KiB
C
52 lines
1.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (c) 2000,2005 Silicon Graphics, Inc.
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* All Rights Reserved.
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*/
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#ifndef __XFS_INODE_ITEM_H__
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#define __XFS_INODE_ITEM_H__
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/* kernel only definitions */
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struct xfs_buf;
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struct xfs_bmbt_rec;
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struct xfs_inode;
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struct xfs_mount;
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struct xfs_inode_log_item {
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struct xfs_log_item ili_item; /* common portion */
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struct xfs_inode *ili_inode; /* inode ptr */
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unsigned short ili_lock_flags; /* inode lock flags */
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/*
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* The ili_lock protects the interactions between the dirty state and
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* the flush state of the inode log item. This allows us to do atomic
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* modifications of multiple state fields without having to hold a
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* specific inode lock to serialise them.
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*
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* We need atomic changes between inode dirtying, inode flushing and
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* inode completion, but these all hold different combinations of
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* ILOCK and IFLUSHING and hence we need some other method of
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* serialising updates to the flush state.
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*/
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spinlock_t ili_lock; /* flush state lock */
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unsigned int ili_last_fields; /* fields when flushed */
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unsigned int ili_fields; /* fields to be logged */
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unsigned int ili_fsync_fields; /* logged since last fsync */
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xfs_lsn_t ili_flush_lsn; /* lsn at last flush */
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xfs_csn_t ili_commit_seq; /* last transaction commit */
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};
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static inline int xfs_inode_clean(struct xfs_inode *ip)
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{
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return !ip->i_itemp || !(ip->i_itemp->ili_fields & XFS_ILOG_ALL);
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}
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extern void xfs_inode_item_init(struct xfs_inode *, struct xfs_mount *);
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extern void xfs_inode_item_destroy(struct xfs_inode *);
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extern void xfs_iflush_abort(struct xfs_inode *);
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extern int xfs_inode_item_format_convert(xfs_log_iovec_t *,
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struct xfs_inode_log_format *);
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extern struct kmem_zone *xfs_ili_zone;
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#endif /* __XFS_INODE_ITEM_H__ */
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