Author | Tokens | Token Proportion | Commits | Commit Proportion |
---|---|---|---|---|
Ralf Hoppe | 752 | 99.08% | 1 | 16.67% |
Linus Torvalds (pre-git) | 5 | 0.66% | 3 | 50.00% |
Greg Kroah-Hartman | 1 | 0.13% | 1 | 16.67% |
Wolfram Sang | 1 | 0.13% | 1 | 16.67% |
Total | 759 | 6 |
// SPDX-License-Identifier: GPL-2.0 /* * SE/HMC Drive (Read) Cache Functions * * Copyright IBM Corp. 2013 * Author(s): Ralf Hoppe (rhoppe@de.ibm.com) * */ #define KMSG_COMPONENT "hmcdrv" #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt #include <linux/kernel.h> #include <linux/mm.h> #include <linux/jiffies.h> #include "hmcdrv_ftp.h" #include "hmcdrv_cache.h" #define HMCDRV_CACHE_TIMEOUT 30 /* aging timeout in seconds */ /** * struct hmcdrv_cache_entry - file cache (only used on read/dir) * @id: FTP command ID * @content: kernel-space buffer, 4k aligned * @len: size of @content cache (0 if caching disabled) * @ofs: start of content within file (-1 if no cached content) * @fname: file name * @fsize: file size * @timeout: cache timeout in jiffies * * Notice that the first three members (id, fname, fsize) are cached on all * read/dir requests. But content is cached only under some preconditions. * Uncached content is signalled by a negative value of @ofs. */ struct hmcdrv_cache_entry { enum hmcdrv_ftp_cmdid id; char fname[HMCDRV_FTP_FIDENT_MAX]; size_t fsize; loff_t ofs; unsigned long timeout; void *content; size_t len; }; static int hmcdrv_cache_order; /* cache allocated page order */ static struct hmcdrv_cache_entry hmcdrv_cache_file = { .fsize = SIZE_MAX, .ofs = -1, .len = 0, .fname = {'\0'} }; /** * hmcdrv_cache_get() - looks for file data/content in read cache * @ftp: pointer to FTP command specification * * Return: number of bytes read from cache or a negative number if nothing * in content cache (for the file/cmd specified in @ftp) */ static ssize_t hmcdrv_cache_get(const struct hmcdrv_ftp_cmdspec *ftp) { loff_t pos; /* position in cache (signed) */ ssize_t len; if ((ftp->id != hmcdrv_cache_file.id) || strcmp(hmcdrv_cache_file.fname, ftp->fname)) return -1; if (ftp->ofs >= hmcdrv_cache_file.fsize) /* EOF ? */ return 0; if ((hmcdrv_cache_file.ofs < 0) || /* has content? */ time_after(jiffies, hmcdrv_cache_file.timeout)) return -1; /* there seems to be cached content - calculate the maximum number * of bytes that can be returned (regarding file size and offset) */ len = hmcdrv_cache_file.fsize - ftp->ofs; if (len > ftp->len) len = ftp->len; /* check if the requested chunk falls into our cache (which starts * at offset 'hmcdrv_cache_file.ofs' in the file of interest) */ pos = ftp->ofs - hmcdrv_cache_file.ofs; if ((pos >= 0) && ((pos + len) <= hmcdrv_cache_file.len)) { memcpy(ftp->buf, hmcdrv_cache_file.content + pos, len); pr_debug("using cached content of '%s', returning %zd/%zd bytes\n", hmcdrv_cache_file.fname, len, hmcdrv_cache_file.fsize); return len; } return -1; } /** * hmcdrv_cache_do() - do a HMC drive CD/DVD transfer with cache update * @ftp: pointer to FTP command specification * @func: FTP transfer function to be used * * Return: number of bytes read/written or a (negative) error code */ static ssize_t hmcdrv_cache_do(const struct hmcdrv_ftp_cmdspec *ftp, hmcdrv_cache_ftpfunc func) { ssize_t len; /* only cache content if the read/dir cache really exists * (hmcdrv_cache_file.len > 0), is large enough to handle the * request (hmcdrv_cache_file.len >= ftp->len) and there is a need * to do so (ftp->len > 0) */ if ((ftp->len > 0) && (hmcdrv_cache_file.len >= ftp->len)) { /* because the cache is not located at ftp->buf, we have to * assemble a new HMC drive FTP cmd specification (pointing * to our cache, and using the increased size) */ struct hmcdrv_ftp_cmdspec cftp = *ftp; /* make a copy */ cftp.buf = hmcdrv_cache_file.content; /* and update */ cftp.len = hmcdrv_cache_file.len; /* buffer data */ len = func(&cftp, &hmcdrv_cache_file.fsize); /* now do */ if (len > 0) { pr_debug("caching %zd bytes content for '%s'\n", len, ftp->fname); if (len > ftp->len) len = ftp->len; hmcdrv_cache_file.ofs = ftp->ofs; hmcdrv_cache_file.timeout = jiffies + HMCDRV_CACHE_TIMEOUT * HZ; memcpy(ftp->buf, hmcdrv_cache_file.content, len); } } else { len = func(ftp, &hmcdrv_cache_file.fsize); hmcdrv_cache_file.ofs = -1; /* invalidate content */ } if (len > 0) { /* cache some file info (FTP command, file name and file * size) unconditionally */ strscpy(hmcdrv_cache_file.fname, ftp->fname, HMCDRV_FTP_FIDENT_MAX); hmcdrv_cache_file.id = ftp->id; pr_debug("caching cmd %d, file size %zu for '%s'\n", ftp->id, hmcdrv_cache_file.fsize, ftp->fname); } return len; } /** * hmcdrv_cache_cmd() - perform a cached HMC drive CD/DVD transfer * @ftp: pointer to FTP command specification * @func: FTP transfer function to be used * * Attention: Notice that this function is not reentrant - so the caller * must ensure exclusive execution. * * Return: number of bytes read/written or a (negative) error code */ ssize_t hmcdrv_cache_cmd(const struct hmcdrv_ftp_cmdspec *ftp, hmcdrv_cache_ftpfunc func) { ssize_t len; if ((ftp->id == HMCDRV_FTP_DIR) || /* read cache */ (ftp->id == HMCDRV_FTP_NLIST) || (ftp->id == HMCDRV_FTP_GET)) { len = hmcdrv_cache_get(ftp); if (len >= 0) /* got it from cache ? */ return len; /* yes */ len = hmcdrv_cache_do(ftp, func); if (len >= 0) return len; } else { len = func(ftp, NULL); /* simply do original command */ } /* invalidate the (read) cache in case there was a write operation * or an error on read/dir */ hmcdrv_cache_file.id = HMCDRV_FTP_NOOP; hmcdrv_cache_file.fsize = LLONG_MAX; hmcdrv_cache_file.ofs = -1; return len; } /** * hmcdrv_cache_startup() - startup of HMC drive cache * @cachesize: cache size * * Return: 0 on success, else a (negative) error code */ int hmcdrv_cache_startup(size_t cachesize) { if (cachesize > 0) { /* perform caching ? */ hmcdrv_cache_order = get_order(cachesize); hmcdrv_cache_file.content = (void *) __get_free_pages(GFP_KERNEL | GFP_DMA, hmcdrv_cache_order); if (!hmcdrv_cache_file.content) { pr_err("Allocating the requested cache size of %zu bytes failed\n", cachesize); return -ENOMEM; } pr_debug("content cache enabled, size is %zu bytes\n", cachesize); } hmcdrv_cache_file.len = cachesize; return 0; } /** * hmcdrv_cache_shutdown() - shutdown of HMC drive cache */ void hmcdrv_cache_shutdown(void) { if (hmcdrv_cache_file.content) { free_pages((unsigned long) hmcdrv_cache_file.content, hmcdrv_cache_order); hmcdrv_cache_file.content = NULL; } hmcdrv_cache_file.id = HMCDRV_FTP_NOOP; hmcdrv_cache_file.fsize = LLONG_MAX; hmcdrv_cache_file.ofs = -1; hmcdrv_cache_file.len = 0; /* no cache */ }
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