forked from Minki/linux
Btrfs: kerneldoc comments for extent_map.c
Add kerneldoc comments for all exported functions. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Chris Mason <chris.mason@oracle.com>
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@ -31,6 +31,14 @@ void extent_map_exit(void)
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kmem_cache_destroy(extent_map_cache);
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}
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/**
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* extent_map_tree_init - initialize extent map tree
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* @tree: tree to initialize
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* @mask: flags for memory allocations during tree operations
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*
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* Initialize the extent tree @tree. Should be called for each new inode
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* or other user of the extent_map interface.
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*/
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void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask)
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{
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tree->map.rb_node = NULL;
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@ -39,6 +47,14 @@ void extent_map_tree_init(struct extent_map_tree *tree, gfp_t mask)
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}
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EXPORT_SYMBOL(extent_map_tree_init);
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/**
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* alloc_extent_map - allocate new extent map structure
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* @mask: memory allocation flags
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*
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* Allocate a new extent_map structure. The new structure is
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* returned with a reference count of one and needs to be
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* freed using free_extent_map()
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*/
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struct extent_map *alloc_extent_map(gfp_t mask)
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{
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struct extent_map *em;
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@ -52,6 +68,13 @@ struct extent_map *alloc_extent_map(gfp_t mask)
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}
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EXPORT_SYMBOL(alloc_extent_map);
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/**
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* free_extent_map - drop reference count of an extent_map
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* @em: extent map beeing releasead
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*
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* Drops the reference out on @em by one and free the structure
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* if the reference count hits zero.
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*/
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void free_extent_map(struct extent_map *em)
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{
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if (!em)
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@ -166,10 +189,15 @@ static int mergable_maps(struct extent_map *prev, struct extent_map *next)
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return 0;
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}
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/*
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* add_extent_mapping tries a simple forward/backward merge with existing
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* mappings. The extent_map struct passed in will be inserted into
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* the tree directly (no copies made, just a reference taken).
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/**
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* add_extent_mapping - add new extent map to the extent tree
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* @tree: tree to insert new map in
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* @em: map to insert
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*
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* Insert @em into @tree or perform a simple forward/backward merge with
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* existing mappings. The extent_map struct passed in will be inserted
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* into the tree directly, with an additional reference taken, or a
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* reference dropped if the merge attempt was sucessfull.
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*/
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int add_extent_mapping(struct extent_map_tree *tree,
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struct extent_map *em)
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@ -220,11 +248,16 @@ static u64 range_end(u64 start, u64 len)
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return start + len;
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}
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/*
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* lookup_extent_mapping returns the first extent_map struct in the
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* tree that intersects the [start, len] range. There may
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* be additional objects in the tree that intersect, so check the object
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* returned carefully to make sure you don't need additional lookups.
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/**
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* lookup_extent_mapping - lookup extent_map
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* @tree: tree to lookup in
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* @start: byte offset to start the search
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* @len: length of the lookup range
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*
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* Find and return the first extent_map struct in @tree that intersects the
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* [start, len] range. There may be additional objects in the tree that
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* intersect, so check the object returned carefully to make sure that no
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* additional lookups are needed.
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*/
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struct extent_map *lookup_extent_mapping(struct extent_map_tree *tree,
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u64 start, u64 len)
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@ -273,9 +306,13 @@ out:
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}
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EXPORT_SYMBOL(lookup_extent_mapping);
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/*
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* removes an extent_map struct from the tree. No reference counts are
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* dropped, and no checks are done to see if the range is in use
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/**
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* remove_extent_mapping - removes an extent_map from the extent tree
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* @tree: extent tree to remove from
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* @em: extent map beeing removed
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*
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* Removes @em from @tree. No reference counts are dropped, and no checks
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* are done to see if the range is in use
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*/
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int remove_extent_mapping(struct extent_map_tree *tree, struct extent_map *em)
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{
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