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vm_page_is_valid (9)

>> vm_page_is_valid (9) ( FreeBSD man: Ядро )

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NAME



vm_page_bits

 
vm_page_set_validclean

 
vm_page_clear_dirty

 
vm_page_set_invalid

 
vm_page_zero_invalid

 
vm_page_is_valid

 
vm_page_test_dirty

 
vm_page_dirty

 
vm_page_undirty

 - manage page clean and dirty bits

SYNOPSIS

   #include <sys/param.h>
   #include <vm/vm.h>
   #include <vm/vm_page.h>
int vm_page_bits (int base int size);
void vm_page_set_validclean (vm_page_t m int base int size);
void vm_page_clear_dirty (vm_page_t m int base int size);
void vm_page_set_invalid (vm_page_t m int base int size);
void vm_page_zero_invalid (vm_page_t m boolean_t setvalid);
int vm_page_is_valid (vm_page_t m int base int size);
void vm_page_test_dirty (vm_page_t m);
void vm_page_dirty (vm_page_t m);
void vm_page_undirty (vm_page_t m);

DESCRIPTION

vm_page_bits ();
calculates the bits representing the DEV_BSIZE range of bytes between Fa base and Fa size . The byte range is expected to be within a single page, and if Fa size is zero, no bits will be set.

vm_page_set_validclean ();
flags the byte range between Fa base and Fa size as valid and clean. The range is expected to be DEV_BSIZE aligned and no larger than PAGE_SIZE If it is not properly aligned, any unaligned chucks of the DEV_BSIZE blocks at the beginning and end of the range will be zeroed.

If Fa base is zero and Fa size is one page, the modified bit in the page map is cleared; as well, the PG_NOSYNC flag is cleared.

vm_page_clear_dirty ();
clears the dirty bits within a page in the range between Fa base and Fa size . The bits representing the range are calculated by calling vm_page_bits (.);

vm_page_set_invalid ();
clears the bits in both the valid and dirty flags representing the DEV_BSIZE blocks between Fa base and Fa size in the page. The bits are calculated by calling vm_page_bits (.);
As well as clearing the bits within the page, the generation number within the object holding the page is incremented.

vm_page_zero_invalid ();
zeroes all of the blocks within the page that are currently flagged as invalid. If Fa setvalid is TRUE all of the valid bits within the page are set.

In some cases, such as NFS, the valid bits cannot be set in order to maintain cache consistency.

vm_page_is_valid ();
checks to determine if the all of the DEV_BSIZE blocks between Fa base and Fa size of the page are valid. If Fa size is zero and the page is entirely invalid vm_page_is_valid ();
will return TRUE in all other cases a size of zero will return FALSE

vm_page_test_dirty ();
checks if a page has been modified via any of its physical maps, and if so, flags the entire page as dirty. vm_page_dirty ();
is called to modify the dirty bits.

vm_page_dirty ();
flags the entire page as dirty. It is expected that the page is not currently on the cache queue.

vm_page_undirty ();
clears all of the dirty bits in a page.

NOTES

None of these functions are allowed to block.

AUTHORS

This manual page was written by An Chad David Aq davidc@acns.ab.ca .

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