projects / thirdparty / man-pages.git / blame
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1 | .\" Hey Emacs! This file is -*- nroff -*- source. |
| 2 | .\" | |
| 3 | .\" Copyright (c) 1995 Michael Chastain (mec@shell.portal.com), 15 April 1995. | |
| 4 | .\" | |
| 5 | .\" This is free documentation; 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; either version 2 of | |
| 8 | .\" the License, or (at your option) any later version. | |
| 9 | .\" | |
| 10 | .\" The GNU General Public License's references to "object code" | |
| 11 | .\" and "executables" are to be interpreted as the output of any | |
| 12 | .\" document formatting or typesetting system, including | |
| 13 | .\" intermediate and printed output. | |
| 14 | .\" | |
| 15 | .\" This manual is distributed in the hope that it will be useful, | |
| 16 | .\" but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 17 | .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 18 | .\" GNU General Public License for more details. | |
| 19 | .\" | |
| 20 | .\" You should have received a copy of the GNU General Public | |
| 21 | .\" License along with this manual; if not, write to the Free | |
| 22 | .\" Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, | |
| 23 | .\" USA. | |
| 24 | .\" | |
| 25 | .\" Modified 1997-01-31 by Eric S. Raymond <esr@thyrsus.com> | |
| c11b1abf | 26 | .\" Modified 2004-06-17 by Michael Kerrisk <mtk.manpages@gmail.com> |
| fea681da | 27 | .\" |
| d9343c5c | 28 | .TH BDFLUSH 2 2004-06-17 "Linux" "Linux Programmer's Manual" |
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29 | .SH NAME |
| 30 | bdflush \- start, flush, or tune buffer-dirty-flush daemon | |
| 31 | .SH SYNOPSIS | |
| 32 | .nf | |
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33 | .B #include <sys/kdaemon.h> |
| 34 | ||
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35 | .BI "int bdflush(int " func ", long *" address ); |
| 36 | .BI "int bdflush(int " func ", long " data ); | |
| 37 | .fi | |
| 38 | .SH DESCRIPTION | |
| e511ffb6 | 39 | .BR bdflush () |
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40 | starts, flushes, or tunes the buffer-dirty-flush daemon. |
| 41 | Only a privileged process (one with the | |
| 42 | .B CAP_SYS_ADMIN | |
| 43 | capability) may call | |
| e511ffb6 | 44 | .BR bdflush (). |
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45 | .PP |
| 46 | If | |
| 47 | .I func | |
| 48 | is negative or 0, and no daemon has been started, then | |
| e511ffb6 | 49 | .BR bdflush () |
| fea681da MK |
50 | enters the daemon code and never returns. |
| 51 | .PP | |
| 52 | If | |
| 53 | .I func | |
| 54 | is 1, | |
| 55 | some dirty buffers are written to disk. | |
| 56 | .PP | |
| 57 | If | |
| 58 | .I func | |
| 59 | is 2 or more and is even (low bit is 0), then | |
| 60 | .I address | |
| 61 | is the address of a long word, | |
| 62 | and the tuning parameter numbered | |
| 63 | .RI "(" "func" "\-2)/2" | |
| 64 | is returned to the caller in that address. | |
| 65 | .PP | |
| 66 | If | |
| 67 | .I func | |
| 68 | is 3 or more and is odd (low bit is 1), then | |
| 69 | .I data | |
| 70 | is a long word, | |
| 71 | and the kernel sets tuning parameter numbered | |
| 72 | .RI "(" "func" "\-3)/2" | |
| 73 | to that value. | |
| 74 | .PP | |
| 75 | The set of parameters, their values, and their legal ranges | |
| 76 | are defined in the kernel source file | |
| 77 | .IR fs/buffer.c . | |
| 78 | .SH "RETURN VALUE" | |
| 79 | If | |
| 80 | .I func | |
| 81 | is negative or 0 and the daemon successfully starts, | |
| e511ffb6 | 82 | .BR bdflush () |
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83 | never returns. |
| 84 | Otherwise, the return value is 0 on success and \-1 on failure, with | |
| 85 | .I errno | |
| 86 | set to indicate the error. | |
| 87 | .SH ERRORS | |
| 88 | .TP | |
| 89 | .B EBUSY | |
| 90 | An attempt was made to enter the daemon code after | |
| 91 | another process has already entered. | |
| 92 | .TP | |
| 93 | .B EFAULT | |
| 94 | .I address | |
| 95 | points outside your accessible address space. | |
| 96 | .TP | |
| 97 | .B EINVAL | |
| 98 | An attempt was made to read or write an invalid parameter number, | |
| 99 | or to write an invalid value to a parameter. | |
| 100 | .TP | |
| 101 | .B EPERM | |
| 102 | Caller does not have the | |
| 103 | .B CAP_SYS_ADMIN | |
| 104 | capability. | |
| 105 | .SH "CONFORMING TO" | |
| 0bfa087b | 106 | .BR bdflush () |
| 8382f16d | 107 | is Linux-specific and should not be used in programs |
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108 | intended to be portable. |
| 109 | .SH "SEE ALSO" | |
| 110 | .BR fsync (2), | |
| 111 | .BR sync (2), | |
| 112 | .BR sync (8), | |
| 113 | .BR update (8) |