137 lines
4.8 KiB
C
137 lines
4.8 KiB
C
/*
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* Copyright (c) 2006-2007 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_FILESTREAM_H__
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#define __XFS_FILESTREAM_H__
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#ifdef __KERNEL__
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struct xfs_mount;
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struct xfs_inode;
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struct xfs_perag;
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struct xfs_bmalloca;
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#ifdef XFS_FILESTREAMS_TRACE
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#define XFS_FSTRM_KTRACE_INFO 1
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#define XFS_FSTRM_KTRACE_AGSCAN 2
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#define XFS_FSTRM_KTRACE_AGPICK1 3
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#define XFS_FSTRM_KTRACE_AGPICK2 4
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#define XFS_FSTRM_KTRACE_UPDATE 5
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#define XFS_FSTRM_KTRACE_FREE 6
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#define XFS_FSTRM_KTRACE_ITEM_LOOKUP 7
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#define XFS_FSTRM_KTRACE_ASSOCIATE 8
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#define XFS_FSTRM_KTRACE_MOVEAG 9
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#define XFS_FSTRM_KTRACE_ORPHAN 10
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#define XFS_FSTRM_KTRACE_SIZE 16384
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extern ktrace_t *xfs_filestreams_trace_buf;
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#endif
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/*
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* Allocation group filestream associations are tracked with per-ag atomic
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* counters. These counters allow _xfs_filestream_pick_ag() to tell whether a
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* particular AG already has active filestreams associated with it. The mount
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* point's m_peraglock is used to protect these counters from per-ag array
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* re-allocation during a growfs operation. When xfs_growfs_data_private() is
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* about to reallocate the array, it calls xfs_filestream_flush() with the
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* m_peraglock held in write mode.
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*
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* Since xfs_mru_cache_flush() guarantees that all the free functions for all
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* the cache elements have finished executing before it returns, it's safe for
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* the free functions to use the atomic counters without m_peraglock protection.
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* This allows the implementation of xfs_fstrm_free_func() to be agnostic about
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* whether it was called with the m_peraglock held in read mode, write mode or
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* not held at all. The race condition this addresses is the following:
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*
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* - The work queue scheduler fires and pulls a filestream directory cache
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* element off the LRU end of the cache for deletion, then gets pre-empted.
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* - A growfs operation grabs the m_peraglock in write mode, flushes all the
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* remaining items from the cache and reallocates the mount point's per-ag
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* array, resetting all the counters to zero.
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* - The work queue thread resumes and calls the free function for the element
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* it started cleaning up earlier. In the process it decrements the
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* filestreams counter for an AG that now has no references.
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*
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* With a shrinkfs feature, the above scenario could panic the system.
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*
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* All other uses of the following macros should be protected by either the
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* m_peraglock held in read mode, or the cache's internal locking exposed by the
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* interval between a call to xfs_mru_cache_lookup() and a call to
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* xfs_mru_cache_done(). In addition, the m_peraglock must be held in read mode
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* when new elements are added to the cache.
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*
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* Combined, these locking rules ensure that no associations will ever exist in
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* the cache that reference per-ag array elements that have since been
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* reallocated.
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*/
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STATIC_INLINE int
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xfs_filestream_peek_ag(
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xfs_mount_t *mp,
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xfs_agnumber_t agno)
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{
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return atomic_read(&mp->m_perag[agno].pagf_fstrms);
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}
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STATIC_INLINE int
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xfs_filestream_get_ag(
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xfs_mount_t *mp,
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xfs_agnumber_t agno)
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{
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return atomic_inc_return(&mp->m_perag[agno].pagf_fstrms);
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}
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STATIC_INLINE int
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xfs_filestream_put_ag(
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xfs_mount_t *mp,
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xfs_agnumber_t agno)
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{
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return atomic_dec_return(&mp->m_perag[agno].pagf_fstrms);
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}
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/* allocation selection flags */
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typedef enum xfs_fstrm_alloc {
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XFS_PICK_USERDATA = 1,
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XFS_PICK_LOWSPACE = 2,
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} xfs_fstrm_alloc_t;
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/* prototypes for filestream.c */
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int xfs_filestream_init(void);
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void xfs_filestream_uninit(void);
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int xfs_filestream_mount(struct xfs_mount *mp);
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void xfs_filestream_unmount(struct xfs_mount *mp);
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void xfs_filestream_flush(struct xfs_mount *mp);
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xfs_agnumber_t xfs_filestream_lookup_ag(struct xfs_inode *ip);
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int xfs_filestream_associate(struct xfs_inode *dip, struct xfs_inode *ip);
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void xfs_filestream_deassociate(struct xfs_inode *ip);
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int xfs_filestream_new_ag(struct xfs_bmalloca *ap, xfs_agnumber_t *agp);
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/* filestreams for the inode? */
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STATIC_INLINE int
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xfs_inode_is_filestream(
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struct xfs_inode *ip)
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{
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return (ip->i_mount->m_flags & XFS_MOUNT_FILESTREAMS) ||
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xfs_iflags_test(ip, XFS_IFILESTREAM) ||
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(ip->i_d.di_flags & XFS_DIFLAG_FILESTREAM);
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}
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#endif /* __KERNEL__ */
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#endif /* __XFS_FILESTREAM_H__ */
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