diff options
author | Ralf Hoppe <rhoppe@de.ibm.com> | 2013-04-08 09:52:57 +0200 |
---|---|---|
committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2014-09-25 10:52:02 +0200 |
commit | 8f933b1043e1e51f4776fc1ffe86752c7785fd4e (patch) | |
tree | 9549e4659cd027279b213bab4e735e1ccd5b15d7 /drivers/s390/char/hmcdrv_cache.c | |
parent | ea61a579ab87f1620b14777afc32cf3827f07bc8 (diff) | |
download | linux-stable-8f933b1043e1e51f4776fc1ffe86752c7785fd4e.tar.gz linux-stable-8f933b1043e1e51f4776fc1ffe86752c7785fd4e.tar.bz2 linux-stable-8f933b1043e1e51f4776fc1ffe86752c7785fd4e.zip |
s390/hmcdrv: HMC drive CD/DVD access
This device driver allows accessing a HMC drive CD/DVD-ROM.
It can be used in a LPAR and z/VM environment.
Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Ralf Hoppe <rhoppe@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'drivers/s390/char/hmcdrv_cache.c')
-rw-r--r-- | drivers/s390/char/hmcdrv_cache.c | 252 |
1 files changed, 252 insertions, 0 deletions
diff --git a/drivers/s390/char/hmcdrv_cache.c b/drivers/s390/char/hmcdrv_cache.c new file mode 100644 index 000000000000..4cda5ada143a --- /dev/null +++ b/drivers/s390/char/hmcdrv_cache.c @@ -0,0 +1,252 @@ +/* + * 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 + */ + strlcpy(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 */ +} |