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<!-- Copyright (C) 2003 Red Hat, Inc.                                -->
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<HTML
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><TITLE
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>Initialization and Mounting</TITLE
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TITLE="eCos Reference Manual"
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TITLE="File System Support Infrastructure"
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>eCos Reference Manual</TH
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><A
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><DIV
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CLASS="CHAPTER"
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><H1
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><A
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NAME="FILEIO-MOUNTING">Chapter 25. Initialization and Mounting</H1
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><P
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>As mentioned previously, mount table entries can be sourced from two
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places. Static entries may be defined by using the
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<TT
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CLASS="LITERAL"
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>MTAB_ENTRY()</TT
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> macro. Such entries will be
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automatically mounted on system startup.  For each entry in the mount
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table that has a non-null <TT
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CLASS="STRUCTFIELD"
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><I
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>name</I
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></TT
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> field the
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filesystem table is searched for a match with the
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<TT
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CLASS="STRUCTFIELD"
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><I
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>fsname</I
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></TT
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> field. If a match is found the
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filesystem's <TT
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CLASS="STRUCTFIELD"
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><I
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>mount</I
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></TT
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> entry is called and if
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successful the mount table entry marked valid and the
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<TT
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CLASS="STRUCTFIELD"
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><I
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>fs</I
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></TT
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> field initialized. The
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<TT
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CLASS="FUNCTION"
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>mount()</TT
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> function is responsible for initializing
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the <TT
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CLASS="STRUCTFIELD"
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><I
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>root</I
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></TT
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> field.</P
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><P
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>The size of the mount table is defined by the configuration value
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<TT
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CLASS="LITERAL"
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>CYGNUM_FILEIO_MTAB_MAX</TT
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>. Any entries that have not
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been statically defined are available for use by dynamic mounts.</P
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><P
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>A filesystem may be mounted dynamically by calling <TT
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CLASS="FUNCTION"
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>mount()</TT
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>. This
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function has the following prototype:</P
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><TABLE
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BORDER="5"
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BGCOLOR="#E0E0F0"
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WIDTH="70%"
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><TR
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><TD
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><PRE
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CLASS="PROGRAMLISTING"
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>int mount( const char *devname,
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           const char *dir,
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           const char *fsname);</PRE
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></TD
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></TR
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></TABLE
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><P
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>The <TT
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CLASS="PARAMETER"
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><I
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>devname</I
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></TT
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> argument identifies a device that
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will be used by this filesystem and will be assigned to the
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<TT
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CLASS="STRUCTFIELD"
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><I
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>devname</I
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></TT
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> field of the mount table entry.</P
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><P
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>The <TT
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CLASS="PARAMETER"
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><I
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>dir</I
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></TT
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> argument is the mount point name, it
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will be assigned to the <TT
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CLASS="STRUCTFIELD"
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><I
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>name</I
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></TT
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> field of the
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mount table entry.</P
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><P
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>The <TT
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CLASS="PARAMETER"
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><I
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>fsname</I
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></TT
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> argument is the name of the
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implementing filesystem, it will be assigned to the
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<TT
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CLASS="STRUCTFIELD"
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><I
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>fsname</I
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></TT
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> entry of the mount table entry.</P
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><P
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>The process of mounting a filesystem dynamically is as follows. First
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a search is made of the mount table for an entry with a NULL
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<TT
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CLASS="STRUCTFIELD"
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><I
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>name</I
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></TT
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> field to be used for the new mount
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point. The filesystem table is then searched for an entry whose name
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matches <TT
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CLASS="STRUCTFIELD"
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><I
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>fsname</I
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></TT
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>. If this is successful then
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the mount table entry is initialized and the filesystem's
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<TT
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CLASS="FUNCTION"
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>mount()</TT
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> operation called. If this is successful,
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the mount table entry is marked valid and the
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<TT
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CLASS="STRUCTFIELD"
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><I
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>fs</I
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></TT
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> field initialized.</P
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><P
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>Unmounting a filesystem is done by the <TT
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CLASS="FUNCTION"
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>umount()</TT
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>
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function. This can unmount filesystems whether they were mounted
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statically or dynamically.</P
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><P
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>The <TT
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CLASS="FUNCTION"
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>umount()</TT
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> function has the following prototype:</P
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><TABLE
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BORDER="5"
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BGCOLOR="#E0E0F0"
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><TR
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><TD
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><PRE
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CLASS="PROGRAMLISTING"
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>int umount( const char *name );</PRE
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></TD
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></TR
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></TABLE
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><P
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>The mount table is searched for a match between the
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<TT
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CLASS="PARAMETER"
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><I
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>name</I
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></TT
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> argument and the entry
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<TT
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CLASS="STRUCTFIELD"
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><I
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>name</I
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></TT
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> field. When a match is found the
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filesystem's <TT
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CLASS="FUNCTION"
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>umount()</TT
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> operation is called and if
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successful, the mount table entry is invalidated by setting its
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<TT
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CLASS="STRUCTFIELD"
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><I
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>valid</I
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></TT
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> field false and the
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<TT
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CLASS="STRUCTFIELD"
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><I
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>name</I
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></TT
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> field to NULL.</P
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