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-rw-r--r--fs/xfs/xfs_filestream.h82
1 files changed, 0 insertions, 82 deletions
diff --git a/fs/xfs/xfs_filestream.h b/fs/xfs/xfs_filestream.h
index 260f757bbc5d..09dd9af45434 100644
--- a/fs/xfs/xfs_filestream.h
+++ b/fs/xfs/xfs_filestream.h
@@ -42,88 +42,6 @@ extern ktrace_t *xfs_filestreams_trace_buf;
42 42
43#endif 43#endif
44 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/*
83 * xfs_filestream_peek_ag is only used in tracing code
84 */
85static inline int
86xfs_filestream_peek_ag(
87 xfs_mount_t *mp,
88 xfs_agnumber_t agno)
89{
90 struct xfs_perag *pag;
91 int ret;
92
93 pag = xfs_perag_get(mp, agno);
94 ret = atomic_read(&pag->pagf_fstrms);
95 xfs_perag_put(pag);
96 return ret;
97}
98
99static inline int
100xfs_filestream_get_ag(
101 xfs_mount_t *mp,
102 xfs_agnumber_t agno)
103{
104 struct xfs_perag *pag;
105 int ret;
106
107 pag = xfs_perag_get(mp, agno);
108 ret = atomic_inc_return(&pag->pagf_fstrms);
109 xfs_perag_put(pag);
110 return ret;
111}
112
113static inline int
114xfs_filestream_put_ag(
115 xfs_mount_t *mp,
116 xfs_agnumber_t agno)
117{
118 struct xfs_perag *pag;
119 int ret;
120
121 pag = xfs_perag_get(mp, agno);
122 ret = atomic_dec_return(&pag->pagf_fstrms);
123 xfs_perag_put(pag);
124 return ret;
125}
126
127/* allocation selection flags */ 45/* allocation selection flags */
128typedef enum xfs_fstrm_alloc { 46typedef enum xfs_fstrm_alloc {
129 XFS_PICK_USERDATA = 1, 47 XFS_PICK_USERDATA = 1,