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Technical Reference: Kernel and Subsystems, Volume 1
vfs_search Kernel Service
Purpose
Searches the vfs list.
Syntax
int vfs_search ( vfs_srchfcn, srchargs)
(int (*vfs_srchfcn)(struct vfs *caddr_t);
caddr_t srchargs;
Parameters
vfs_srchfcn |
Points to a search function. The search function is identified by
the vfs_srchfcn parameter. This function is used to
examine or modify an entry in the vfs list. The search function is called
once for each currently active VFS. If the search function returns a value
of 0, iteration through the vfs list continues to the next entry. If the return
value is nonzero, vfs_search kernel service returns
to its caller, passing back the return value from the search function. |
|
When the system invokes this function, the system passes it a pointer
to a virtual file system (VFS) and the srchargs parameter. |
srchargs |
Points to data to be used by the serach function. This pointer is
not used by the vfs_search kernel service but is passed
to the search function. |
Description
The vfs_search kernel service
searches the vfs list. This kernel service allows a process outside the file
system to search the vfs list. The vfs_search kernel
service locks out all activity in the vfs list during a search. Then, the
kernel service iterates through the vfs list and calls the search function
on each entry.
The search function must not request locks that could
result in deadlock. In particular, any attempt to do lock operations on the
vfs list or on other VFS structures could produce deadlock.
The performance of the vfs_search kernel service may not be acceptable for functions requiring quick response.
Iterating through the vfs list and making an indirect function call for each
structure is inherently slow.
Execution Environment
The vfs_search kernel service
can be called from the process environment only.
Return Values
This kernel service returns the value returned by
the last call to the search function.
Related Information
List of Virtual File System Operations.
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