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VFS: Slight rework of the FD disconnect feature.

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* This should fix ticket #4157, although I probably have missed
  something.
* In any case, it no longer messes with the ref counts of the
  file descriptor, and the race condition in put_fd() should be
  gone.
* It's still rather messy all in all.
This commit is contained in:
Axel Dörfler
2015-09-11 17:25:01 +02:00
parent 6adf7a0c75
commit eb62d3337b
2 changed files with 23 additions and 28 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/system/kernel/fs/fd.cpp
+21 -27
View File
@@ -1,6 +1,6 @@
/*
* Copyright 2009-2011, Ingo Weinhold, [email protected].
* Copyright 2002-2010, Axel Dörfler, [email protected].
* Copyright 2002-2015, Axel Dörfler, [email protected].
* Distributed under the terms of the MIT License.
*/
@@ -224,13 +224,11 @@ put_fd(struct file_descriptor* descriptor)
descriptor->ops->fd_free(descriptor);
// prevent this descriptor from being closed/freed again
descriptor->open_count = -1;
descriptor->ref_count = -1;
descriptor->ops = NULL;
descriptor->u.vnode = NULL;
// the file descriptor is kept intact, so that it's not
// reused until someone explicetly closes it
// reused until someone explicitly closes it
}
}
@@ -295,13 +293,8 @@ get_fd_locked(struct io_context* context, int fd)
struct file_descriptor* descriptor = context->fds[fd];
if (descriptor != NULL) {
// Disconnected descriptors cannot be accessed anymore
if (descriptor->open_mode & O_DISCONNECTED)
descriptor = NULL;
else {
TFD(GetFD(context, fd, descriptor));
inc_fd_ref_count(descriptor);
}
TFD(GetFD(context, fd, descriptor));
inc_fd_ref_count(descriptor);
}
return descriptor;
@@ -323,7 +316,7 @@ get_open_fd(struct io_context* context, int fd)
MutexLocker _(context->io_mutex);
file_descriptor* descriptor = get_fd_locked(context, fd);
if (descriptor == NULL)
if (descriptor == NULL || (descriptor->open_mode & O_DISCONNECTED) != 0)
return NULL;
atomic_add(&descriptor->open_count, 1);
@@ -427,7 +420,8 @@ dup2_fd(int oldfd, int newfd, bool kernel)
// the table size could be changed)
if ((uint32)oldfd >= context->table_size
|| (uint32)newfd >= context->table_size
|| context->fds[oldfd] == NULL) {
|| context->fds[oldfd] == NULL
|| (context->fds[oldfd]->open_mode & O_DISCONNECTED) != 0) {
mutex_unlock(&context->io_mutex);
return B_FILE_ERROR;
}
@@ -508,10 +502,10 @@ fd_ioctl(bool kernelFD, int fd, uint32 op, void* buffer, size_t length)
int status;
descriptor = get_fd(get_current_io_context(kernelFD), fd);
if (descriptor == NULL)
if (descriptor == NULL || (descriptor->open_mode & O_DISCONNECTED) != 0)
return B_FILE_ERROR;
if (descriptor->ops->fd_ioctl)
if (descriptor->ops->fd_ioctl != NULL)
status = descriptor->ops->fd_ioctl(descriptor, op, buffer, length);
else
status = B_DEV_INVALID_IOCTL;
@@ -567,7 +561,7 @@ select_fd(int32 fd, struct select_info* info, bool kernel)
MutexLocker locker(context->io_mutex);
struct file_descriptor* descriptor = fdGetter.SetTo(context, fd, true);
if (descriptor == NULL)
if (descriptor == NULL || (descriptor->open_mode & O_DISCONNECTED) != 0)
return B_FILE_ERROR;
uint16 eventsToSelect = info->selected_events & ~B_EVENT_INVALID;
@@ -685,7 +679,7 @@ fd_is_valid(int fd, bool kernel)
{
struct file_descriptor* descriptor
= get_fd(get_current_io_context(kernel), fd);
if (descriptor == NULL)
if (descriptor == NULL || (descriptor->open_mode & O_DISCONNECTED) != 0)
return false;
put_fd(descriptor);
@@ -726,7 +720,7 @@ common_user_io(int fd, off_t pos, void* buffer, size_t length, bool write)
FDGetter fdGetter;
struct file_descriptor* descriptor = fdGetter.SetTo(fd, false);
if (!descriptor)
if (descriptor == NULL || (descriptor->open_mode & O_DISCONNECTED) != 0)
return B_FILE_ERROR;
if (write ? (descriptor->open_mode & O_RWMASK) == O_RDONLY
@@ -778,7 +772,7 @@ common_user_vector_io(int fd, off_t pos, const iovec* userVecs, size_t count,
FDGetter fdGetter;
struct file_descriptor* descriptor = fdGetter.SetTo(fd, false);
if (!descriptor)
if (descriptor == NULL || (descriptor->open_mode & O_DISCONNECTED) != 0)
return B_FILE_ERROR;
if (write ? (descriptor->open_mode & O_RWMASK) == O_RDONLY
@@ -891,12 +885,12 @@ _user_seek(int fd, off_t pos, int seekType)
struct file_descriptor* descriptor;
descriptor = get_fd(get_current_io_context(false), fd);
if (!descriptor)
if (descriptor == NULL || (descriptor->open_mode & O_DISCONNECTED) != 0)
return B_FILE_ERROR;
TRACE(("user_seek(descriptor = %p)\n", descriptor));
if (descriptor->ops->fd_seek)
if (descriptor->ops->fd_seek != NULL)
pos = descriptor->ops->fd_seek(descriptor, pos, seekType);
else
pos = ESPIPE;
@@ -937,7 +931,7 @@ _user_read_dir(int fd, struct dirent* userBuffer, size_t bufferSize,
io_context* ioContext = get_current_io_context(false);
FDGetter fdGetter;
struct file_descriptor* descriptor = fdGetter.SetTo(ioContext, fd, false);
if (descriptor == NULL)
if (descriptor == NULL || (descriptor->open_mode & O_DISCONNECTED) != 0)
return B_FILE_ERROR;
if (descriptor->ops->fd_read_dir == NULL)
@@ -983,10 +977,10 @@ _user_rewind_dir(int fd)
TRACE(("user_rewind_dir(fd = %d)\n", fd));
descriptor = get_fd(get_current_io_context(false), fd);
if (descriptor == NULL)
if (descriptor == NULL || (descriptor->open_mode & O_DISCONNECTED) != 0)
return B_FILE_ERROR;
if (descriptor->ops->fd_rewind_dir)
if (descriptor->ops->fd_rewind_dir != NULL)
status = descriptor->ops->fd_rewind_dir(descriptor);
else
status = B_UNSUPPORTED;
@@ -1124,7 +1118,7 @@ _kern_write(int fd, off_t pos, const void* buffer, size_t length)
FDGetter fdGetter;
struct file_descriptor* descriptor = fdGetter.SetTo(fd, true);
if (descriptor == NULL)
if (descriptor == NULL || (descriptor->open_mode & O_DISCONNECTED) != 0)
return B_FILE_ERROR;
if ((descriptor->open_mode & O_RWMASK) == O_RDONLY)
return B_FILE_ERROR;
@@ -1252,7 +1246,7 @@ _kern_read_dir(int fd, struct dirent* buffer, size_t bufferSize,
struct io_context* ioContext = get_current_io_context(true);
descriptor = get_fd(ioContext, fd);
if (descriptor == NULL)
if (descriptor == NULL || (descriptor->open_mode & O_DISCONNECTED) != 0)
return B_FILE_ERROR;
if (descriptor->ops->fd_read_dir) {
@@ -1278,7 +1272,7 @@ _kern_rewind_dir(int fd)
TRACE(("sys_rewind_dir(fd = %d)\n",fd));
descriptor = get_fd(get_current_io_context(true), fd);
if (descriptor == NULL)
if (descriptor == NULL || (descriptor->open_mode & O_DISCONNECTED) != 0)
return B_FILE_ERROR;
if (descriptor->ops->fd_rewind_dir)
src/system/kernel/fs/vfs.cpp
+2 -1
View File
@@ -4864,7 +4864,8 @@ vfs_new_io_context(io_context* parentContext, bool purgeCloseOnExec)
for (i = 0; i < tableSize; i++) {
struct file_descriptor* descriptor = parentContext->fds[i];
if (descriptor != NULL) {
if (descriptor != NULL
&& (descriptor->open_mode & O_DISCONNECTED) == 0) {
bool closeOnExec = fd_close_on_exec(parentContext, i);
if (closeOnExec && purgeCloseOnExec)
continue;