puffs_flush(3) - NetBSD Manual Pages

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PUFFS_FLUSH(3)          NetBSD Library Functions Manual         PUFFS_FLUSH(3)


NAME

     puffs_flush -- puffs kernel cache flushing and invalidation routines


LIBRARY

     puffs Convenience Library (libpuffs, -lpuffs)


SYNOPSIS

     #include <puffs.h>

     int
     puffs_inval_namecache_dir(struct puffs_usermount *pu,
         puffs_cookie_t cookie);

     int
     puffs_inval_namecache_all(struct puffs_usermount *pu);

     int
     puffs_inval_pagecache_node(struct puffs_usermount *pu,
         puffs_cookie_t cookie);

     int
     puffs_inval_pagecache_node_range(struct puffs_usermount *pu,
         puffs_cookie_t cookie, off_t start, off_t end);

     int
     puffs_flush_pagecache_node(struct puffs_usermount *pu,
         puffs_cookie_t cookie);

     int
     puffs_flush_pagecache_node_range(struct puffs_usermount *pu,
         puffs_cookie_t cookie, off_t start, off_t end);


DESCRIPTION

     These routines are used inform the kernel that any information it might
     have cached is no longer valid.  puffs_inval_namecache_dir() invalidates
     the name cache for a given directory.  The argument cookie should
     describe an existing and valid directory cookie for the file system.
     Similarly, puffs_inval_namecache_all() invalidates the name cache for the
     entire file system (this routine might go away).

     The cached pages (file contents) for a regular file described by cookie
     are invalidated using puffs_inval_pagecache_node().  A specific range can
     be invalidated using puffs_inval_pagecache_node_range() for a platform
     specific page level granularity.  The offset start will be truncated to a
     page boundary while end will be rounded up to the next page boundary.  As
     a special case, specifying 0 as end will invalidate all contents from
     start to the end of the file.

     It is especially important to note that these routines will not only
     invalidate data in the "read cache", but also data in the "write back"
     cache (conceptually speaking; in reality they are the same cache), which
     has not yet been flushed to the file server.  Therefore any unflushed
     data will be lost.

     The counterparts of the invalidation routines are the flushing routines
     puffs_flush_pagecache_node() and puffs_flush_pagecache_node_range(),
     which force unwritten data from the kernel page cache to be written.  For
     the flush range version, the same range rules as with the invalidation
     routine apply.  The data is flushed asynchronously, i.e. if the routine
     returns successfully, all the caller knows is that the data has been
     queued for writing.


SEE ALSO

     puffs(3)

NetBSD 5.0                       April 7, 2007                      NetBSD 5.0