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zdsfs: add online vtoc refresh

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Enable zdsfs to access datasets that were created after zdsfs was
mounted without the need to remount zdsfs.
This is done by re-reading the VTOC with every readdir system call.
To ensure a consistent VTOC state the DASD device is reserved for
every VTOC read and released afterwards.

Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Reviewed-by: Jan Hoeppner <hoeppner@linux.ibm.com>
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
This commit is contained in:
Stefan Haberland
2018-12-11 17:27:34 +01:00
committed by Jan Höppner
parent e9c030f202
commit bc053a975a
6 changed files with 280 additions and 131 deletions
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6
include/lib/dasd_base.h
View File

@@ -170,6 +170,10 @@ struct hd_geometry {
#define BIODASDDISABLE _IO(DASD_IOCTL_LETTER, 0)
/* Enable the volume (for Linux) */
#define BIODASDENABLE _IO(DASD_IOCTL_LETTER, 1)
/* Reserve the device for the current LPAR */
#define BIODASDRSRV _IO(DASD_IOCTL_LETTER, 2)
/* Release the device for the current LPAR */
#define BIODASDRLSE _IO(DASD_IOCTL_LETTER, 3)
/* Get information on a dasd device (enhanced) */
#define BIODASDINFO2 _IOR(DASD_IOCTL_LETTER, 3, dasd_information2_t)
/* #define BIODASDFORMAT _IOW(IOCTL_LETTER,0,format_data_t) , deprecated */
@@ -203,5 +207,7 @@ int dasd_get_geo(const char *device, struct hd_geometry *geo);
int dasd_get_info(const char *device, dasd_information2_t *info);
int dasd_is_ro(const char *device, bool *ro);
int dasd_reread_partition_table(const char *device, int ntries);
int dasd_disk_reserve(const char *device);
int dasd_disk_release(const char *device);
#endif /* LIB_DASD_BASE_H */

83
include/lib/libzds.h
View File

@@ -112,6 +112,8 @@
*/
#define LIB_LIBZDS_H
#include "lib/util_base.h"
#include "lib/util_list.h"
#include "vtoc.h"
@@ -328,11 +330,74 @@ struct pds_member_entry {
*/
struct zdsroot;
/**
* @struct raw_vtoc
* @brief The VTOC is a directory of data sets on one DASD
*
* As the VTOC is the data area on the DASD that describes all data sets,
* this library will often have to refer to the various records in the VTOC.
* To make this more efficient, we will read the whole VTOC once and identify
* all elements (DSCBs). The raw data of the VTOC tracks and the index to the
* DSCBs is stored.
*/
struct raw_vtoc {
/** @brief The raw track data */
char *rawdata;
/** @brief This size of the raw track data in bytes */
unsigned long long rawdatasize;
/** @brief An array with pointers to the various DSCBs in the rawdata */
char **vtocindex;
/** @brief Number of entries in the index */
unsigned int vtocindexcount;
/** @brief Number of records per VTOC track
*
* @note While the DS4DEVDT field in the format 4 DSCB names the number
* if DSCBs per VTOC track, we count the records, which is DS4DEVDT + 1
* for record 0.
*/
unsigned int vtoc_rec_per_track;
/** @brief The track number at which the vtoc begins on the DASD */
unsigned int vtoctrackoffset;
/** @brief Start record of VTOC.
*
* The rawdata contains full tracks. This is the number of the first
* record that actually belongs to the VTOC
*/
unsigned int vtocrecno;
/** @brief The DASD this vtoc was read from */
struct dasd *dasd;
/** @brief Detailed error messages in case of a problem */
struct errorlog *log;
};
/**
* @struct dasd
* @brief Represents one physical device, may have a vtoc
*/
struct dasd;
struct dasd {
/** @brief List head used to store a list of DASDs in struct zdsroot */
struct util_list_node list;
/** @brief Name of the block device, e.g. /dev/dasde */
char *device;
/** @brief File descriptor for the block device.
*
* The device is kept open for as along as the library uses it.
* This lets the system know that the device is still in use.
*/
int inusefd;
/* @brief where to find the volume label */
unsigned int label_block;
/** @brief Device geometry. How many cylinders does the DASD have. */
unsigned int cylinders;
/** @brief Device geometry. How many heads does the DASD have. */
unsigned int heads;
/** @brief The VTOC data that has been read from this device */
struct raw_vtoc *rawvtoc;
/** @brief The volume label that has been read from this device */
volume_label_t *vlabel;
/** @brief Detailed error messages in case of a problem */
struct errorlog *log;
};
/**
* @struct dasditerator
@@ -350,12 +415,6 @@ struct dasditerator;
*/
struct dasdhandle;
/**
* @struct raw_vtoc
* @brief The VTOC is a directory of data sets on one dasd
*/
struct raw_vtoc;
/**
* @struct dscbiterator
* @brief allows to iterate over all DSCBs in a vtoc
@@ -572,7 +631,13 @@ int lzds_dasd_get_vlabel(struct dasd *dasd, struct volume_label **vlabel);
* @brief Read the vtoc data from device. The data as stored as part
* of the struct dasd.
*/
int lzds_dasd_read_rawvtoc(struct dasd *dasd);
int lzds_dasd_read_rawvtoc(struct dasd *dasd, struct raw_vtoc *vtoc);
/**
* @brief Read the vtoc data from device. The data as stored as part
* of the struct dasd.
*/
int lzds_dasd_alloc_rawvtoc(struct dasd *dasd);
/**
* @brief Get the previously read raw_vtoc data.
@@ -787,6 +852,8 @@ int lzds_zdsroot_extract_datasets_from_dasd(struct zdsroot *root,
struct dasd *dasd);
void lzds_dslist_free(struct zdsroot *root);
/** @} */ /* end of group libzds_functions_high */