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Add loop teardown logic

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git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1238 42af7a65-404d-4744-a932-0658087f49c3
This commit is contained in:
patacongo 2008-11-15 00:20:34 +00:00
parent 6aeb99bc51
commit 386b7f12cd
1 changed files with 182 additions and 41 deletions
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223
drivers/loop.c
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@ -43,12 +43,14 @@
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/mount.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <semaphore.h>
#include <debug.h>
#include <errno.h>
@ -58,14 +60,20 @@
* Private Definitions
****************************************************************************/
#define loop_semgive(d) sem_post(&(d)->sem) /* To match loop_semtake */
#define MAX_OPENCNT (255) /* Limit of ubyte */
/****************************************************************************
* Private Types
****************************************************************************/
struct loop_struct_s
{
sem_t sem; /* For safe read-modify-write operations */
uint32 nsectors; /* Number of sectors on device */
off_t offset; /* Offset (in bytes) to the first sector */
uint16 sectsize; /* The size of one sector */
ubyte opencnt; /* Count of open references to the loop device */
#ifdef CONFIG_FS_WRITABLE
boolean writeenabled; /* TRUE: can write to device */
#endif
@ -76,6 +84,7 @@ struct loop_struct_s
* Private Function Prototypes
****************************************************************************/
static void loop_semtake(FAR struct loop_struct_s *dev);
static int loop_open(FAR struct inode *inode);
static int loop_close(FAR struct inode *inode);
static ssize_t loop_read(FAR struct inode *inode, unsigned char *buffer,
@ -108,6 +117,24 @@ static const struct block_operations g_bops =
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: loop_semtake
****************************************************************************/
static void loop_semtake(FAR struct loop_struct_s *dev)
{
/* Take the semaphore (perhaps waiting) */
while (sem_wait(&dev->sem) != 0)
{
/* The only case that an error should occur here is if
* the wait was awakened by a signal.
*/
ASSERT(errno == EINTR);
}
}
/****************************************************************************
* Name: loop_open
*
@ -117,11 +144,27 @@ static const struct block_operations g_bops =
static int loop_open(FAR struct inode *inode)
{
return OK;
FAR struct loop_struct_s *dev;
int ret = OK;
DEBUGASSERT(inode && inode->i_private);
dev = (FAR struct loop_struct_s *)inode->i_private;
loop_semtake(dev);
if (dev->opencnt == MAX_OPENCNT)
{
return -EMFILE;
}
else
{
dev->opencnt++;
}
loop_semgive(dev);
return ret;
}
/****************************************************************************
* Name: loop_closel
* Name: loop_close
*
* Description: close the block device
*
@ -129,7 +172,23 @@ static int loop_open(FAR struct inode *inode)
static int loop_close(FAR struct inode *inode)
{
return OK;
FAR struct loop_struct_s *dev;
int ret = OK;
DEBUGASSERT(inode && inode->i_private);
dev = (FAR struct loop_struct_s *)inode->i_private;
loop_semtake(dev);
if (dev->opencnt == 0)
{
return -EIO;
}
else
{
dev->opencnt--;
}
loop_semgive(dev);
return ret;
}
/****************************************************************************
@ -142,21 +201,28 @@ static int loop_close(FAR struct inode *inode)
static ssize_t loop_read(FAR struct inode *inode, unsigned char *buffer,
size_t start_sector, unsigned int nsectors)
{
struct loop_struct_s *dev;
FAR struct loop_struct_s *dev;
size_t nbytesread;
off_t offset;
int ret;
DEBUGASSERT(inode && inode->i_private);
dev = (struct loop_struct_s *)inode->i_private;
dev = (FAR struct loop_struct_s *)inode->i_private;
if (start_sector + nsectors > dev->nsectors)
{
dbg("Seek failed for offset=%d: %d\n", (int)offset, errno);
return -EIO;
}
/* Calculate the offset to read the sectors and seek to the position */
offset = start_sector * dev->sectsize;
offset = start_sector * dev->sectsize + offset;
ret = lseek(dev->fd, offset, SEEK_SET);
if (ret == (off_t)-1)
{
dbg("Seek failed for offset=%d: %d\n", (int)offset, errno);
return -EIO;
}
/* Then read the requested number of sectors from that position */
@ -188,17 +254,17 @@ static ssize_t loop_read(FAR struct inode *inode, unsigned char *buffer,
static ssize_t loop_write(FAR struct inode *inode, const unsigned char *buffer,
size_t start_sector, unsigned int nsectors)
{
struct loop_struct_s *dev;
FAR struct loop_struct_s *dev;
size_t nbyteswritten;
off_t offset;
int ret;
DEBUGASSERT(inode && inode->i_private);
dev = (struct loop_struct_s *)inode->i_private;
dev = (FAR struct loop_struct_s *)inode->i_private;
/* Calculate the offset to write the sectors and seek to the position */
offset = start_sector * dev->sectsize;
offset = start_sector * dev->sectsize + offset;
ret = lseek(dev->fd, offset, SEEK_SET);
if (ret == (off_t)-1)
{
@ -233,12 +299,12 @@ static ssize_t loop_write(FAR struct inode *inode, const unsigned char *buffer,
static int loop_geometry(FAR struct inode *inode, struct geometry *geometry)
{
struct loop_struct_s *dev;
FAR struct loop_struct_s *dev;
DEBUGASSERT(inode);
if (geometry)
{
dev = (struct loop_struct_s *)inode->i_private;
dev = (FAR struct loop_struct_s *)inode->i_private;
geometry->geo_available = TRUE;
geometry->geo_mediachanged = FALSE;
#ifdef CONFIG_FS_WRITABLE
@ -261,22 +327,22 @@ static int loop_geometry(FAR struct inode *inode, struct geometry *geometry)
* Name: losetup
*
* Description:
* Setup the loop device so that it exports the file referenced by 'name'
* Setup the loop device so that it exports the file referenced by 'filename'
* as a block device.
*
****************************************************************************/
int losetup(const char *name, int minor, uint16 sectsize)
int losetup(const char *devname, const char *filename, uint16 sectsize,
off_t offset, boolean readonly)
{
struct loop_struct_s *dev;
FAR struct loop_struct_s *dev;
struct stat sb;
char devname[16];
int ret;
/* Sanity check */
#ifdef CONFIG_DEBUG
if (minor < 0 || minor > 255 || !name || !sectsize)
if (!devname || !filename || !sectsize)
{
return -EINVAL;
}
@ -284,16 +350,16 @@ int losetup(const char *name, int minor, uint16 sectsize)
/* Get the size of the file */
ret = stat(name, &sb);
ret = stat(filename, &sb);
if (ret < 0)
{
dbg("Failed to stat %s: %d\n", name, errno);
dbg("Failed to stat %s: %d\n", filename, errno);
return -errno;
}
/* Check if the file system is big enough for one block */
if (sb.st_size < sectsize)
if (sb.st_size - offset < sectsize)
{
dbg("File is too small for blocksize\n");
return -ERANGE;
@ -301,18 +367,33 @@ int losetup(const char *name, int minor, uint16 sectsize)
/* Allocate a loop device structure */
dev = (struct loop_struct_s *)malloc(sizeof(struct loop_struct_s));
dev = (FAR struct loop_struct_s *)zalloc(sizeof(struct loop_struct_s));
if (!dev)
{
return -ENOMEM;
}
/* Open the file. First try to open the device W/R */
/* Initialize the geometry */
dev->nsectors = (sb.st_size - offset) / sectsize;
dev->sectsize = sectsize;
dev->offset = offset;
/* Open the file. */
#ifdef CONFIG_FS_WRITABLE
dev->writeenabled = FALSE; /* Assume failure */
dev->fd = -1;
/* First try to open the device R/W access (unless we are asked
* to open it readonly).
*/
if (!readonly)
{
dev->fd = open(filename, O_RDWR);
}
dev->fd = open(name, O_RDWR);
if (dev->fd >= 0)
{
dev->writeenabled = TRUE; /* Success */
@ -322,32 +403,92 @@ int losetup(const char *name, int minor, uint16 sectsize)
{
/* If that fails, then try to open the device read-only */
dev->fd = open(name, O_RDWR);
dev->fd = open(filename, O_RDWR);
if (dev->fd < 0)
{
dbg("Failed to open %s: %d\n", name, errno);
free(dev);
return -errno;
dbg("Failed to open %s: %d\n", filename, errno);
ret = -errno;
goto errout_with_dev;
}
}
/* Initialize the remaining fields */
/* Inode private data will be reference to the loop device structure */
dev->nsectors = sb.st_size / sectsize; /* Number of sectors on device */
dev->sectsize = sectsize; /* The size of one sector */
ret = register_blockdriver(devname, &g_bops, 0, dev);
if (ret < 0)
{
fdbg("register_blockdriver failed: %d\n", -ret);
goto errout_with_fd;
}
/* Create a loop device name */
snprintf(devname, 16, "/dev/loop%d", minor);
/* Inode private data is a reference to the loop device stgructure */
ret = register_blockdriver(devname, &g_bops, 0, dev);
if (ret < 0)
{
fdbg("register_blockdriver failed: %d\n", -ret);
free(dev);
}
return OK;
errout_with_fd:
close(dev->fd);
errout_with_dev:
free(dev);
return ret;
}
/****************************************************************************
* Name: loteardown
*
* Description:
* Undo the setup performed by losetup
*
****************************************************************************/
int loteardown(const char *devname)
{
FAR struct loop_struct_s *dev;
FAR struct inode *inode;
int ret;
/* Sanity check */
#ifdef CONFIG_DEBUG
if (!devname)
{
return -EINVAL;
}
#endif
/* Open the block driver associated with devname so that we can get the inode
* reference.
*/
ret = open_blockdriver(devname, MS_RDONLY, &inode);
if (ret < 0)
{
dbg("Failed to open %s: %d\n", devname, -ret);
return ret;
}
/* Inode private data is a reference to the loop device stgructure */
dev = (FAR struct loop_struct_s *)inode->i_private;
close_blockdriver(inode);
DEBUGASSERT(dev);
/* Are there still open references to the device */
if (dev->opencnt > 0)
{
return -EBUSY;
}
/* Otherwise, unregister the block device */
ret = unregister_blockdriver(devname);
/* Release the device structure */
if (dev->fd >= 0)
{
(void)close(dev->fd);
}
free(dev);
return ret;
}