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58d6ea3085
xa_store() differs from radix_tree_insert() in that it will overwrite an existing element in the array rather than returning an error. This is the behaviour which most users want, and those that want more complex behaviour generally want to use the xas family of routines anyway. For memory allocation, xa_store() will first attempt to request memory from the slab allocator; if memory is not immediately available, it will drop the xa_lock and allocate memory, keeping a pointer in the xa_state. It does not use the per-CPU cache, although those will continue to exist until all radix tree users are converted to the xarray. This patch also includes xa_erase() and __xa_erase() for a streamlined way to store NULL. Since there is no need to allocate memory in order to store a NULL in the XArray, we do not need to trouble the user with deciding what memory allocation flags to use. Signed-off-by: Matthew Wilcox <willy@infradead.org>
24 lines
599 B
C
24 lines
599 B
C
/* lib/bitmap.c pulls in at least two other files. */
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#include <linux/bitmap.h>
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void bitmap_clear(unsigned long *map, unsigned int start, int len)
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{
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unsigned long *p = map + BIT_WORD(start);
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const unsigned int size = start + len;
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int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
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unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
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while (len - bits_to_clear >= 0) {
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*p &= ~mask_to_clear;
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len -= bits_to_clear;
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bits_to_clear = BITS_PER_LONG;
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mask_to_clear = ~0UL;
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p++;
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}
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if (len) {
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mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
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*p &= ~mask_to_clear;
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}
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}
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