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840b80af74
pcache_meta_find_latest() already computes the metadata address as meta_addr. Reuse that instead of recomputing. Signed-off-by: Li Chen <chenl311@chinatelecom.cn> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
118 lines
3.5 KiB
C
118 lines
3.5 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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#ifndef _PCACHE_INTERNAL_H
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#define _PCACHE_INTERNAL_H
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#include <linux/delay.h>
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#include <linux/crc32c.h>
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#define pcache_err(fmt, ...) \
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pr_err("dm-pcache: %s:%u " fmt, __func__, __LINE__, ##__VA_ARGS__)
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#define pcache_info(fmt, ...) \
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pr_info("dm-pcache: %s:%u " fmt, __func__, __LINE__, ##__VA_ARGS__)
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#define pcache_debug(fmt, ...) \
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pr_debug("dm-pcache: %s:%u " fmt, __func__, __LINE__, ##__VA_ARGS__)
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#define PCACHE_KB (1024ULL)
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#define PCACHE_MB (1024 * PCACHE_KB)
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/* Maximum number of metadata indices */
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#define PCACHE_META_INDEX_MAX 2
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#define PCACHE_CRC_SEED 0x3B15A
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/*
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* struct pcache_meta_header - PCACHE metadata header structure
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* @crc: CRC checksum for validating metadata integrity.
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* @seq: Sequence number to track metadata updates.
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* @version: Metadata version.
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* @res: Reserved space for future use.
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*/
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struct pcache_meta_header {
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__u32 crc;
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__u8 seq;
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__u8 version;
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__u16 res;
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};
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/*
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* pcache_meta_crc - Calculate CRC for the given metadata header.
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* @header: Pointer to the metadata header.
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* @meta_size: Size of the metadata structure.
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*
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* Returns the CRC checksum calculated by excluding the CRC field itself.
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*/
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static inline u32 pcache_meta_crc(struct pcache_meta_header *header, u32 meta_size)
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{
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return crc32c(PCACHE_CRC_SEED, (void *)header + 4, meta_size - 4);
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}
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/*
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* pcache_meta_seq_after - Check if a sequence number is more recent, accounting for overflow.
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* @seq1: First sequence number.
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* @seq2: Second sequence number.
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*
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* Determines if @seq1 is more recent than @seq2 by calculating the signed
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* difference between them. This approach allows handling sequence number
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* overflow correctly because the difference wraps naturally, and any value
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* greater than zero indicates that @seq1 is "after" @seq2. This method
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* assumes 8-bit unsigned sequence numbers, where the difference wraps
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* around if seq1 overflows past seq2.
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*
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* Returns:
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* - true if @seq1 is more recent than @seq2, indicating it comes "after"
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* - false otherwise.
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*/
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static inline bool pcache_meta_seq_after(u8 seq1, u8 seq2)
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{
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return (s8)(seq1 - seq2) > 0;
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}
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/*
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* pcache_meta_find_latest - Find the latest valid metadata.
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* @header: Pointer to the metadata header.
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* @meta_size: Size of each metadata block.
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*
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* Finds the latest valid metadata by checking sequence numbers. If a
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* valid entry with the highest sequence number is found, its pointer
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* is returned. Returns NULL if no valid metadata is found.
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*/
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static inline void __must_check *pcache_meta_find_latest(struct pcache_meta_header *header,
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u32 meta_size, u32 meta_max_size,
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void *meta_ret)
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{
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struct pcache_meta_header *meta, *latest = NULL;
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u32 i, seq_latest = 0;
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void *meta_addr;
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meta = meta_ret;
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for (i = 0; i < PCACHE_META_INDEX_MAX; i++) {
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meta_addr = (void *)header + (i * meta_max_size);
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if (copy_mc_to_kernel(meta, meta_addr, meta_size)) {
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pcache_err("hardware memory error when copy meta");
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return ERR_PTR(-EIO);
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}
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/* Skip if CRC check fails, which means corrupted */
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if (meta->crc != pcache_meta_crc(meta, meta_size))
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continue;
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/* Update latest if a more recent sequence is found */
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if (!latest || pcache_meta_seq_after(meta->seq, seq_latest)) {
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seq_latest = meta->seq;
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latest = meta_addr;
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}
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}
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if (!latest)
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return NULL;
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if (copy_mc_to_kernel(meta_ret, latest, meta_size)) {
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pcache_err("hardware memory error");
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return ERR_PTR(-EIO);
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}
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return latest;
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}
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#endif /* _PCACHE_INTERNAL_H */
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