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1 | From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 |
2 | From: Brian Behlendorf <behlendorf1@llnl.gov> | |
3 | Date: Thu, 19 Oct 2017 10:06:55 -0700 | |
4 | Subject: [PATCH] Remove vn_rename and vn_remove dependency | |
5 | MIME-Version: 1.0 | |
6 | Content-Type: text/plain; charset=UTF-8 | |
7 | Content-Transfer-Encoding: 8bit | |
8 | ||
9 | The only place vn_rename and vn_remove are used is when writing | |
10 | out an updated pool configuration file. By truncating the file | |
11 | instead of renaming and removing it we can avoid having to implement | |
12 | these interfaces entirely. Functionally an empty cache file is | |
13 | treated the same as a missing cache file. This is particularly | |
14 | advantageous because the Linux kernel has never provided a way | |
15 | to reliably implement vn_rename and vn_remove. | |
16 | ||
17 | The cachefile_004_pos.ksh test case was updated to understand | |
18 | that an empty cache file is the same as a missing one. | |
19 | ||
20 | The zfs-import-* systemd service files were not updated to use | |
21 | ConditionFileNotEmpty in place of ConditionPathExists. This | |
22 | means that after exporting all pools and rebooting new pools | |
23 | will not the scanned for on the next boot. This small change | |
24 | should not impact normal usage since pools are not exported | |
25 | as part of a normal shutdown. | |
26 | ||
27 | Documentation was updated accordingly. | |
28 | ||
29 | Reviewed-by: George Melikov <mail@gmelikov.ru> | |
30 | Reviewed-by: Arkadiusz Bubała <arkadiusz.bubala@open-e.com> | |
31 | Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> | |
32 | Closes zfsonlinux/spl#648 | |
33 | Closes #6753 | |
34 | (cherry picked from commit 5d62588032aa1d13d7f789cf564a0d20c77a5762) | |
35 | Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com> | |
36 | --- | |
37 | module/zfs/spa_config.c | 34 ++++++++++++++++++---- | |
38 | man/man8/zpool.8 | 2 +- | |
39 | .../functional/cachefile/cachefile_004_pos.ksh | 6 ++-- | |
40 | 3 files changed, 32 insertions(+), 10 deletions(-) | |
41 | ||
42 | diff --git a/module/zfs/spa_config.c b/module/zfs/spa_config.c | |
43 | index 5b792b868..fea239014 100644 | |
44 | --- a/module/zfs/spa_config.c | |
45 | +++ b/module/zfs/spa_config.c | |
46 | @@ -147,6 +147,26 @@ out: | |
47 | kobj_close_file(file); | |
48 | } | |
49 | ||
50 | +static int | |
51 | +spa_config_remove(spa_config_dirent_t *dp) | |
52 | +{ | |
53 | +#if defined(__linux__) && defined(_KERNEL) | |
54 | + int error, flags = FWRITE | FTRUNC; | |
55 | + uio_seg_t seg = UIO_SYSSPACE; | |
56 | + vnode_t *vp; | |
57 | + | |
58 | + error = vn_open(dp->scd_path, seg, flags, 0644, &vp, 0, 0); | |
59 | + if (error == 0) { | |
60 | + (void) VOP_FSYNC(vp, FSYNC, kcred, NULL); | |
61 | + (void) VOP_CLOSE(vp, 0, 1, 0, kcred, NULL); | |
62 | + } | |
63 | + | |
64 | + return (error); | |
65 | +#else | |
66 | + return (vn_remove(dp->scd_path, UIO_SYSSPACE, RMFILE)); | |
67 | +#endif | |
68 | +} | |
69 | + | |
70 | static int | |
71 | spa_config_write(spa_config_dirent_t *dp, nvlist_t *nvl) | |
72 | { | |
73 | @@ -161,7 +181,10 @@ spa_config_write(spa_config_dirent_t *dp, nvlist_t *nvl) | |
74 | * If the nvlist is empty (NULL), then remove the old cachefile. | |
75 | */ | |
76 | if (nvl == NULL) { | |
77 | - err = vn_remove(dp->scd_path, UIO_SYSSPACE, RMFILE); | |
78 | + err = spa_config_remove(dp); | |
79 | + if (err == ENOENT) | |
80 | + err = 0; | |
81 | + | |
82 | return (err); | |
83 | } | |
84 | ||
85 | @@ -174,9 +197,9 @@ spa_config_write(spa_config_dirent_t *dp, nvlist_t *nvl) | |
86 | #if defined(__linux__) && defined(_KERNEL) | |
87 | /* | |
88 | * Write the configuration to disk. Due to the complexity involved | |
89 | - * in performing a rename from within the kernel the file is truncated | |
90 | - * and overwritten in place. In the event of an error the file is | |
91 | - * unlinked to make sure we always have a consistent view of the data. | |
92 | + * in performing a rename and remove from within the kernel the file | |
93 | + * is instead truncated and overwritten in place. This way we always | |
94 | + * have a consistent view of the data or a zero length file. | |
95 | */ | |
96 | err = vn_open(dp->scd_path, UIO_SYSSPACE, oflags, 0644, &vp, 0, 0); | |
97 | if (err == 0) { | |
98 | @@ -186,9 +209,8 @@ spa_config_write(spa_config_dirent_t *dp, nvlist_t *nvl) | |
99 | err = VOP_FSYNC(vp, FSYNC, kcred, NULL); | |
100 | ||
101 | (void) VOP_CLOSE(vp, oflags, 1, 0, kcred, NULL); | |
102 | - | |
103 | if (err) | |
104 | - (void) vn_remove(dp->scd_path, UIO_SYSSPACE, RMFILE); | |
105 | + (void) spa_config_remove(dp); | |
106 | } | |
107 | #else | |
108 | /* | |
109 | diff --git a/man/man8/zpool.8 b/man/man8/zpool.8 | |
110 | index 328ba3dce..22579101a 100644 | |
111 | --- a/man/man8/zpool.8 | |
112 | +++ b/man/man8/zpool.8 | |
113 | @@ -655,7 +655,7 @@ Because the kernel destroys and recreates this file when pools are added and | |
114 | removed, care should be taken when attempting to access this file. | |
115 | When the last pool using a | |
116 | .Sy cachefile | |
117 | -is exported or destroyed, the file is removed. | |
118 | +is exported or destroyed, the file will be empty. | |
119 | .It Sy comment Ns = Ns Ar text | |
120 | A text string consisting of printable ASCII characters that will be stored | |
121 | such that it is available even if the pool becomes faulted. | |
122 | diff --git a/tests/zfs-tests/tests/functional/cachefile/cachefile_004_pos.ksh b/tests/zfs-tests/tests/functional/cachefile/cachefile_004_pos.ksh | |
123 | index ae54a9365..e0b81e166 100755 | |
124 | --- a/tests/zfs-tests/tests/functional/cachefile/cachefile_004_pos.ksh | |
125 | +++ b/tests/zfs-tests/tests/functional/cachefile/cachefile_004_pos.ksh | |
126 | @@ -98,13 +98,13 @@ log_must zpool set cachefile=$CPATH2 $TESTPOOL1 | |
127 | log_must pool_in_cache $TESTPOOL1 $CPATH2 | |
128 | log_must zpool set cachefile=$CPATH2 $TESTPOOL2 | |
129 | log_must pool_in_cache $TESTPOOL2 $CPATH2 | |
130 | -if [[ -f $CPATH1 ]]; then | |
131 | +if [[ -s $CPATH1 ]]; then | |
132 | log_fail "Verify set when cachefile is set on pool." | |
133 | fi | |
134 | ||
135 | log_must zpool export $TESTPOOL1 | |
136 | log_must zpool export $TESTPOOL2 | |
137 | -if [[ -f $CPATH2 ]]; then | |
138 | +if [[ -s $CPATH2 ]]; then | |
139 | log_fail "Verify export when cachefile is set on pool." | |
140 | fi | |
141 | ||
142 | @@ -117,7 +117,7 @@ log_must pool_in_cache $TESTPOOL2 $CPATH2 | |
143 | ||
144 | log_must zpool destroy $TESTPOOL1 | |
145 | log_must zpool destroy $TESTPOOL2 | |
146 | -if [[ -f $CPATH2 ]]; then | |
147 | +if [[ -s $CPATH2 ]]; then | |
148 | log_fail "Verify destroy when cachefile is set on pool." | |
149 | fi | |
150 | ||
151 | -- | |
152 | 2.14.2 | |
153 |