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1 | /* |
2 | * Copyright (c) 2006-2007 Silicon Graphics, Inc. |
3 | * All Rights Reserved. |
4 | * |
5 | * This program is free software; you can redistribute it and/or |
6 | * modify it under the terms of the GNU General Public License as |
7 | * published by the Free Software Foundation. |
8 | * |
9 | * This program is distributed in the hope that it would be useful, |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
12 | * GNU General Public License for more details. |
13 | * |
14 | * You should have received a copy of the GNU General Public License |
15 | * along with this program; if not, write the Free Software Foundation, |
16 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
17 | */ |
18 | #ifndef __XFS_FILESTREAM_H__ |
19 | #define __XFS_FILESTREAM_H__ |
20 | |
21 | #ifdef __KERNEL__ |
22 | |
23 | struct xfs_mount; |
24 | struct xfs_inode; |
25 | struct xfs_perag; |
26 | struct xfs_bmalloca; |
27 | |
28 | #ifdef XFS_FILESTREAMS_TRACE |
29 | #define XFS_FSTRM_KTRACE_INFO 1 |
30 | #define XFS_FSTRM_KTRACE_AGSCAN 2 |
31 | #define XFS_FSTRM_KTRACE_AGPICK1 3 |
32 | #define XFS_FSTRM_KTRACE_AGPICK2 4 |
33 | #define XFS_FSTRM_KTRACE_UPDATE 5 |
34 | #define XFS_FSTRM_KTRACE_FREE 6 |
35 | #define XFS_FSTRM_KTRACE_ITEM_LOOKUP 7 |
36 | #define XFS_FSTRM_KTRACE_ASSOCIATE 8 |
37 | #define XFS_FSTRM_KTRACE_MOVEAG 9 |
38 | #define XFS_FSTRM_KTRACE_ORPHAN 10 |
39 | |
40 | #define XFS_FSTRM_KTRACE_SIZE 16384 |
41 | extern ktrace_t *xfs_filestreams_trace_buf; |
42 | |
43 | #endif |
44 | |
45 | /* |
46 | * Allocation group filestream associations are tracked with per-ag atomic |
47 | * counters. These counters allow _xfs_filestream_pick_ag() to tell whether a |
48 | * particular AG already has active filestreams associated with it. The mount |
49 | * point's m_peraglock is used to protect these counters from per-ag array |
50 | * re-allocation during a growfs operation. When xfs_growfs_data_private() is |
51 | * about to reallocate the array, it calls xfs_filestream_flush() with the |
52 | * m_peraglock held in write mode. |
53 | * |
54 | * Since xfs_mru_cache_flush() guarantees that all the free functions for all |
55 | * the cache elements have finished executing before it returns, it's safe for |
56 | * the free functions to use the atomic counters without m_peraglock protection. |
57 | * This allows the implementation of xfs_fstrm_free_func() to be agnostic about |
58 | * whether it was called with the m_peraglock held in read mode, write mode or |
59 | * not held at all. The race condition this addresses is the following: |
60 | * |
61 | * - The work queue scheduler fires and pulls a filestream directory cache |
62 | * element off the LRU end of the cache for deletion, then gets pre-empted. |
63 | * - A growfs operation grabs the m_peraglock in write mode, flushes all the |
64 | * remaining items from the cache and reallocates the mount point's per-ag |
65 | * array, resetting all the counters to zero. |
66 | * - The work queue thread resumes and calls the free function for the element |
67 | * it started cleaning up earlier. In the process it decrements the |
68 | * filestreams counter for an AG that now has no references. |
69 | * |
70 | * With a shrinkfs feature, the above scenario could panic the system. |
71 | * |
72 | * All other uses of the following macros should be protected by either the |
73 | * m_peraglock held in read mode, or the cache's internal locking exposed by the |
74 | * interval between a call to xfs_mru_cache_lookup() and a call to |
75 | * xfs_mru_cache_done(). In addition, the m_peraglock must be held in read mode |
76 | * when new elements are added to the cache. |
77 | * |
78 | * Combined, these locking rules ensure that no associations will ever exist in |
79 | * the cache that reference per-ag array elements that have since been |
80 | * reallocated. |
81 | */ |
82 | STATIC_INLINE int |
83 | xfs_filestream_peek_ag( |
84 | xfs_mount_t *mp, |
85 | xfs_agnumber_t agno) |
86 | { |
87 | return atomic_read(&mp->m_perag[agno].pagf_fstrms); |
88 | } |
89 | |
90 | STATIC_INLINE int |
91 | xfs_filestream_get_ag( |
92 | xfs_mount_t *mp, |
93 | xfs_agnumber_t agno) |
94 | { |
95 | return atomic_inc_return(&mp->m_perag[agno].pagf_fstrms); |
96 | } |
97 | |
98 | STATIC_INLINE int |
99 | xfs_filestream_put_ag( |
100 | xfs_mount_t *mp, |
101 | xfs_agnumber_t agno) |
102 | { |
103 | return atomic_dec_return(&mp->m_perag[agno].pagf_fstrms); |
104 | } |
105 | |
106 | /* allocation selection flags */ |
107 | typedef enum xfs_fstrm_alloc { |
108 | XFS_PICK_USERDATA = 1, |
109 | XFS_PICK_LOWSPACE = 2, |
110 | } xfs_fstrm_alloc_t; |
111 | |
112 | /* prototypes for filestream.c */ |
113 | int xfs_filestream_init(void); |
114 | void xfs_filestream_uninit(void); |
115 | int xfs_filestream_mount(struct xfs_mount *mp); |
116 | void xfs_filestream_unmount(struct xfs_mount *mp); |
117 | void xfs_filestream_flush(struct xfs_mount *mp); |
118 | xfs_agnumber_t xfs_filestream_lookup_ag(struct xfs_inode *ip); |
119 | int xfs_filestream_associate(struct xfs_inode *dip, struct xfs_inode *ip); |
120 | void xfs_filestream_deassociate(struct xfs_inode *ip); |
121 | int xfs_filestream_new_ag(struct xfs_bmalloca *ap, xfs_agnumber_t *agp); |
122 | |
123 | |
124 | /* filestreams for the inode? */ |
125 | STATIC_INLINE int |
126 | xfs_inode_is_filestream( |
127 | struct xfs_inode *ip) |
128 | { |
129 | return (ip->i_mount->m_flags & XFS_MOUNT_FILESTREAMS) || |
130 | xfs_iflags_test(ip, XFS_IFILESTREAM) || |
131 | (ip->i_d.di_flags & XFS_DIFLAG_FILESTREAM); |
132 | } |
133 | |
134 | #endif /* __KERNEL__ */ |
135 | |
136 | #endif /* __XFS_FILESTREAM_H__ */ |
137 |
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