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drivers/loop: Don't use file descriptors... Use the internal file system interfaces so that the loop device can be shared across threads.

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This commit is contained in:
Gregory Nutt 2017-11-02 16:31:56 -06:00
parent c6942f6137
commit f9e7b84727
3 changed files with 49 additions and 35 deletions
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2
TODO
View File

@ -1983,7 +1983,7 @@ o File system / Generic drivers (fs/, drivers/)
accidentlly enabling the feature.
Status: Open
Priority: Since this is a new feature, the priority must be low (unless,
of course, someone is in dire need of the featurea).
of course, someone is in dire need of the feature).
o Graphics Subsystem (graphics/)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

5
drivers/loop/loop.c
View File

@ -93,7 +93,8 @@ static ssize_t loop_read(FAR struct file *filep, FAR char *buffer, size_t len)
* Name: loop_write
****************************************************************************/
static ssize_t loop_write(FAR struct file *filep, FAR const char *buffer, size_t len)
static ssize_t loop_write(FAR struct file *filep, FAR const char *buffer,
size_t len)
{
return len; /* Say that everything was written */
}
@ -125,7 +126,7 @@ static int loop_ioctl(FAR struct file *filep, int cmd, unsigned long arg)
else
{
ret = losetup(setup->devname, setup->filename, setup->sectsize,
setup->offset, setup->readonly);
setup->offset, setup->readonly);
}
}
break;

77
drivers/loop/losetup.c
View File

@ -82,7 +82,7 @@ struct loop_struct_s
#ifdef CONFIG_FS_WRITABLE
bool writeenabled; /* true: can write to device */
#endif
int fd; /* Descriptor of char device/file */
struct file devfile; /* File struct of char device/file */
};
/****************************************************************************
@ -143,7 +143,7 @@ static int loop_semtake(FAR struct loop_struct_s *dev)
* awakened by a signal.
*/
DEBUGASSERT(ret == -EINTR);
DEBUGASSERT(ret == OK || ret == -EINTR);
return ret;
}
@ -241,17 +241,18 @@ static ssize_t loop_read(FAR struct inode *inode, FAR unsigned char *buffer,
if (start_sector + nsectors > dev->nsectors)
{
_err("ERROR: Read past end of file\n");
ferr("ERROR: Read past end of file\n");
return -EIO;
}
/* Calculate the offset to read the sectors and seek to the position */
offset = start_sector * dev->sectsize + dev->offset;
ret = lseek(dev->fd, offset, SEEK_SET);
ret = file_seek(&dev->devfile, offset, SEEK_SET);
if (ret == (off_t)-1)
{
_err("ERROR: Seek failed for offset=%d: %d\n", (int)offset, get_errno());
ferr("ERROR: Seek failed for offset=%d: %d\n",
(int)offset, get_errno());
return -EIO;
}
@ -259,10 +260,11 @@ static ssize_t loop_read(FAR struct inode *inode, FAR unsigned char *buffer,
do
{
nbytesread = nx_read(dev->fd, buffer, nsectors * dev->sectsize);
nbytesread = file_read(&dev->devfile, buffer,
nsectors * dev->sectsize);
if (nbytesread < 0 && nbytesread != -EINTR)
{
_err("ERROR: Read failed: %d\n", nbytesread);
ferr("ERROR: Read failed: %d\n", nbytesread);
return (int)nbytesread;
}
}
@ -296,10 +298,10 @@ static ssize_t loop_write(FAR struct inode *inode,
/* Calculate the offset to write the sectors and seek to the position */
offset = start_sector * dev->sectsize + dev->offset;
ret = lseek(dev->fd, offset, SEEK_SET);
ret = file_seek(&dev->devfile, offset, SEEK_SET);
if (ret == (off_t)-1)
{
_err("ERROR: Seek failed for offset=%d: %d\n",
ferr("ERROR: Seek failed for offset=%d: %d\n",
(int)offset, get_errno());
}
@ -307,10 +309,11 @@ static ssize_t loop_write(FAR struct inode *inode,
do
{
nbyteswritten = nx_write(dev->fd, buffer, nsectors * dev->sectsize);
nbyteswritten = file_write(&dev->devfile, buffer,
nsectors * dev->sectsize);
if (nbyteswritten < 0 && nbyteswritten != -EINTR)
{
_err("ERROR: nx_write failed: %d\n", nbyteswritten);
ferr("ERROR: nx_write failed: %d\n", nbyteswritten);
return nbyteswritten;
}
}
@ -372,11 +375,12 @@ int losetup(FAR const char *devname, FAR const char *filename,
FAR struct loop_struct_s *dev;
struct stat sb;
int ret;
int fd;
/* Sanity check */
#ifdef CONFIG_DEBUG_FEATURES
if (!devname || !filename || !sectsize)
if (devname == NULL || filename == NULL || sectsize == 0)
{
return -EINVAL;
}
@ -387,7 +391,7 @@ int losetup(FAR const char *devname, FAR const char *filename,
ret = stat(filename, &sb);
if (ret < 0)
{
_err("ERROR: Failed to stat %s: %d\n", filename, get_errno());
ferr("ERROR: Failed to stat %s: %d\n", filename, get_errno());
return -get_errno();
}
@ -395,14 +399,15 @@ int losetup(FAR const char *devname, FAR const char *filename,
if (sb.st_size - offset < sectsize)
{
_err("ERROR: File is too small for blocksize\n");
ferr("ERROR: File is too small for blocksize\n");
return -ERANGE;
}
/* Allocate a loop device structure */
dev = (FAR struct loop_struct_s *)kmm_zalloc(sizeof(struct loop_struct_s));
if (!dev)
dev = (FAR struct loop_struct_s *)
kmm_zalloc(sizeof(struct loop_struct_s));
if (dev == NULL)
{
return -ENOMEM;
}
@ -417,19 +422,16 @@ int losetup(FAR const char *devname, FAR const char *filename,
/* 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);
fd = open(filename, O_RDWR);
}
if (dev->fd >= 0)
if (fd >= 0)
{
dev->writeenabled = true; /* Success */
}
@ -438,28 +440,39 @@ int losetup(FAR const char *devname, FAR const char *filename,
{
/* If that fails, then try to open the device read-only */
dev->fd = open(filename, O_RDWR);
if (dev->fd < 0)
fd = open(filename, O_RDWR);
if (fd < 0)
{
_err("ERROR: Failed to open %s: %d\n", filename, get_errno());
ret = -get_errno();
ferr("ERROR: Failed to open %s: %d\n", filename, ret);
goto errout_with_dev;
}
}
/* Detach the file from the file descriptor */
ret = file_detach(fd, &dev->devfile);
if (ret < 0)
{
ferr("ERROR: Failed to open %s: %d\n", filename, ret);
close(fd);
goto errout_with_dev;
}
/* Inode private data will be reference to the loop device structure */
ret = register_blockdriver(devname, &g_bops, 0, dev);
if (ret < 0)
{
ferr("ERROR: register_blockdriver failed: %d\n", -ret);
goto errout_with_fd;
goto errout_with_file;
}
return OK;
errout_with_fd:
close(dev->fd);
errout_with_file:
file_close_detached(&dev->devfile);
errout_with_dev:
kmm_free(dev);
return ret;
@ -482,7 +495,7 @@ int loteardown(FAR const char *devname)
/* Sanity check */
#ifdef CONFIG_DEBUG_FEATURES
if (!devname)
if (devname == NULL)
{
return -EINVAL;
}
@ -495,7 +508,7 @@ int loteardown(FAR const char *devname)
ret = open_blockdriver(devname, MS_RDONLY, &inode);
if (ret < 0)
{
_err("ERROR: Failed to open %s: %d\n", devname, -ret);
ferr("ERROR: Failed to open %s: %d\n", devname, -ret);
return ret;
}
@ -504,7 +517,7 @@ int loteardown(FAR const char *devname)
dev = (FAR struct loop_struct_s *)inode->i_private;
close_blockdriver(inode);
DEBUGASSERT(dev);
DEBUGASSERT(dev != NULL);
/* Are there still open references to the device */
@ -519,9 +532,9 @@ int loteardown(FAR const char *devname)
/* Release the device structure */
if (dev->fd >= 0)
if (dev->devfile.f_inode != NULL)
{
(void)close(dev->fd);
(void)file_close_detached(&dev->devfile);
}
kmm_free(dev);