static AlignedPool alignedPool;
#endif
+/*
+ * Although, support for preadv()/pwrite() first appeared in Linux 2.6.30,
+ * library support was added in glibc 2.10. Hence these functions
+ * are not available in any header file.
+ */
+
+#if defined(__linux__)
+
+extern ssize_t preadv(int fd, const struct iovec *iov, int iovcnt,
+ off_t offset) __attribute__ ((weak));
+extern ssize_t pwritev(int fd, const struct iovec *iov, int iovcnt,
+ off_t offset) __attribute__ ((weak));
+
+#endif /* defined(__linux__) */
+
/*
*-----------------------------------------------------------------------------
*
retval = writev(fd->posix, vPtr, numVec);
if (retval == -1) {
+ if (errno == EINTR) {
+ NOT_TESTED();
+ continue;
+ }
fret = FileIOErrno2Result(errno);
break;
}
/*
*----------------------------------------------------------------------
*
- * FileIO_Preadv --
+ * FileIOPreadvCoalesced --
*
- * Implementation of vector pread. The incoming vectors are
+ * This function implements vector pread for platforms that do not
+ * support the preadv system call. The incoming vectors are
* coalesced to a single buffer to issue only one pread()
* system call which reads from a specified offset. The
* vectors are then decoalesced before return.
*----------------------------------------------------------------------
*/
-FileIOResult
-FileIO_Preadv(FileIODescriptor *fd, // IN: File descriptor
- struct iovec *entries, // IN: Vector to read into
- int numEntries, // IN: Number of vector entries
- uint64 offset, // IN: Offset to start reading
- size_t totalSize) // IN: totalSize (bytes) in entries
+static FileIOResult
+FileIOPreadvCoalesced(FileIODescriptor *fd, // IN: File descriptor
+ struct iovec *entries, // IN: Vector to read into
+ int numEntries, // IN: Number of vector entries
+ uint64 offset, // IN: Offset to start reading
+ size_t totalSize) // IN: totalSize(bytes) in entries
{
- size_t sum = 0;
struct iovec *vPtr;
struct iovec coV;
int count;
uint64 fileOffset;
FileIOResult fret;
Bool didCoalesce;
-
- ASSERT(fd);
- ASSERT(entries);
- ASSERT(!(fd->flags & FILEIO_ASYNCHRONOUS));
- ASSERT_NOT_IMPLEMENTED(totalSize < 0x80000000);
+ size_t sum = 0;
didCoalesce = FileIOCoalesce(entries, numEntries, totalSize, FALSE,
TRUE /* force coalescing */, fd->flags, &coV);
/*
*----------------------------------------------------------------------
*
- * FileIO_Pwritev --
+ * FileIOPwritevCoalesced --
*
- * Implementation of vector pwrite. The incoming vectors are
+ * This function implements vector pwrite for platforms that do not
+ * support the pwritev system call. The incoming vectors are
* coalesced to a single buffer to issue only one pwrite()
* system call which writes from a specified offset. The
* vectors are then decoalesced before return.
*----------------------------------------------------------------------
*/
-FileIOResult
-FileIO_Pwritev(FileIODescriptor *fd, // IN: File descriptor
- struct iovec *entries, // IN: Vector to write from
- int numEntries, // IN: Number of vector entries
- uint64 offset, // IN: Offset to start writing
- size_t totalSize) // IN: Total size (bytes) in entries
+static FileIOResult
+FileIOPwritevCoalesced(FileIODescriptor *fd, // IN: File descriptor
+ struct iovec *entries, // IN: Vector to write from
+ int numEntries, // IN: Number of vector entries
+ uint64 offset, // IN: Offset to start writing
+ size_t totalSize) // IN: Total size(bytes)
{
struct iovec coV;
Bool didCoalesce;
struct iovec *vPtr;
int count;
- size_t sum = 0;
uint64 fileOffset;
FileIOResult fret;
-
- ASSERT(fd);
- ASSERT(entries);
- ASSERT(!(fd->flags & FILEIO_ASYNCHRONOUS));
- ASSERT_NOT_IMPLEMENTED(totalSize < 0x80000000);
+ size_t sum = 0;
didCoalesce = FileIOCoalesce(entries, numEntries, totalSize, TRUE,
TRUE /* force coalescing */, fd->flags, &coV);
if (didCoalesce) {
FileIODecoalesce(&coV, entries, numEntries, sum, TRUE, fd->flags);
}
+ return fret;
+}
+
+#endif /* defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) ||
+ defined(sun) */
+
+
+#if defined(__linux__ )
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileIOPreadvInternal --
+ *
+ * This function implements vector pread for linux builds. Although,
+ * support for preadv() first appeared in Linux 2.6.30,
+ * library support was added in glibc 2.10.
+ * Hence using weak linkage technique, we try to call the more
+ * optimized preadv system call. If the system does not support
+ * this, we fall back to earlier unoptimized techique.
+ *
+ * Note that in linux, preadv can succeed on the first N vectors,
+ * and return a positive value in spite of the fact that there was
+ * an error on the N+1st vector. There is no way to query the exact
+ * error that happened. So, we retry in a loop (for a max of
+ * MAX_RWV_RETRIES), same as FileIO_Readv().
+ *
+ * XXX: If we retried MAX_RWV_RETRIES times and gave up, we will
+ * return FILEIO_ERROR even if errno is undefined.
+ *
+ * Results:
+ * FILEIO_SUCCESS, FILEIO_ERROR
+ *
+ * Side effects:
+ * None
+ *
+ *----------------------------------------------------------------------
+ */
+static FileIOResult
+FileIOPreadvInternal(FileIODescriptor *fd, // IN: File descriptor
+ struct iovec *entries, // IN: Vector to read into
+ int numEntries, // IN: Number of vector entries
+ uint64 offset, // IN: Offset to start reading
+ size_t totalSize) // IN: totalSize(bytes) in entries
+{ struct iovec *vPtr;
+ int numVec;
+ size_t bytesRead = 0;
+ size_t sum = 0;
+ int nRetries = 0;
+ int maxRetries = numEntries;
+ FileIOResult fret = FILEIO_ERROR;
+
+ numVec = numEntries;
+ vPtr = entries;
+
+ while (nRetries < maxRetries) {
+ ssize_t retval = 0;
+
+ ASSERT(numVec > 0);
+ if (preadv != NULL) {
+ retval = preadv(fd->posix, vPtr, numVec, offset);
+ } else {
+ fret = FileIOPreadvCoalesced(fd, entries, numEntries, offset,
+ totalSize);
+ break;
+ }
+ if (retval == -1) {
+ if (errno == EINTR) {
+ NOT_TESTED();
+ continue;
+ }
+ if (errno == ENOSYS) {
+ /*
+ * Function not supported by system. Fallback to unoptimized
+ * function.
+ */
+ ASSERT (nRetries == 0);
+ fret = FileIOPreadvCoalesced(fd, entries, numEntries, offset,
+ totalSize);
+ break;
+ }
+ fret = FileIOErrno2Result(errno);
+ break;
+ }
+ bytesRead += retval;
+ if (retval == 0) {
+ fret = FILEIO_READ_ERROR_EOF;
+ break;
+ }
+ if (bytesRead == totalSize) {
+ fret = FILEIO_SUCCESS;
+ break;
+ }
+ /*
+ * This is an ambiguous case in linux preadv implementation.
+ * If the bytesRead matches an exact iovector boundary, we need
+ * to retry from the next iovec. However, if it does not match,
+ * EOF is the only error possible. Linux 3.4.4 continues to have
+ * this behaviour.
+ * NOTE: If Linux preadv implementation changes, this
+ * ambiguity handling may need to change.
+ */
+
+ for (; sum <= bytesRead; vPtr++, numVec--) {
+ sum += vPtr->iov_len;
+
+ /*
+ * In each syscall, we will process atleast one iovec
+ * or get an error back. We will therefore retry at most
+ * count times. If multiple iovecs were processed before
+ * an error hit, we will retry a lesser number of times.
+ */
+
+ nRetries++;
+ }
+ if (sum > bytesRead) {
+ // A partially filled iovec can ONLY mean EOF
+ fret = FILEIO_READ_ERROR_EOF;
+ break;
+ }
+ }
return fret;
+
}
+
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileIOPwritevInternal --
+ *
+ * This function implements vector pwrite for linux builds. Although,
+ * support for pwritev() first appeared in Linux 2.6.30, library
+ * support was added in glibc 2.10.
+ * Hence using weak linkage technique, we try to call the more
+ * optimized pwritev system call. If the system does not support
+ * this, we fall back to earlier unoptimized techique.
+ *
+ * Note that in linux, pwritev can succeed on the first N vectors,
+ * and return a positive value in spite of the fact that there was
+ * an error on the N+1st vector. There is no way to query the exact
+ * error that happened. So, we retry in a loop (for a max of
+ * MAX_RWV_RETRIES), same as FileIO_Writev().
+ *
+ * XXX: If we retried MAX_RWV_RETRIES times and gave up, we will
+ * return FILEIO_ERROR even if errno is undefined.
+ *
+ * Results:
+ * FILEIO_SUCCESS, FILEIO_ERROR
+ *
+ * Side effects:
+ * None
+ *
+ *----------------------------------------------------------------------
+ */
+
+static FileIOResult
+FileIOPwritevInternal(FileIODescriptor *fd, // IN: File descriptor
+ struct iovec *entries, // IN: Vector to write from
+ int numEntries, // IN: Number of vector entries
+ uint64 offset, // IN: Offset to start writing
+ size_t totalSize) // IN: Total size(bytes)in entries
+{
+ struct iovec *vPtr;
+ int numVec;
+ size_t bytesWritten = 0;
+ size_t sum = 0;
+ int nRetries = 0;
+ int maxRetries = numEntries;
+ FileIOResult fret = FILEIO_ERROR;
+
+ numVec = numEntries;
+ vPtr = entries;
+ while (nRetries < maxRetries) {
+ ssize_t retval = 0;
+
+ ASSERT(numVec > 0);
+
+ if (pwritev != NULL) {
+ retval = pwritev(fd->posix, vPtr, numVec, offset);
+ } else {
+ fret = FileIOPwritevCoalesced(fd, entries, numEntries, offset,
+ totalSize);
+ break;
+ }
+ if (retval == -1) {
+ if (errno == EINTR) {
+ NOT_TESTED();
+ continue;
+ }
+ if (errno == ENOSYS) {
+ /*
+ * Function not supported by system. Fallback to unoptimized
+ * function.
+ */
+ ASSERT (nRetries == 0);
+ fret = FileIOPwritevCoalesced(fd, entries, numEntries, offset,
+ totalSize);
+ break;
+ }
+ fret = FileIOErrno2Result(errno);
+ break;
+ }
+
+ bytesWritten += retval;
+ if (bytesWritten == totalSize) {
+ fret = FILEIO_SUCCESS;
+ break;
+ }
+ NOT_TESTED();
+ for (; sum <= bytesWritten; vPtr++, numVec--) {
+ sum += vPtr->iov_len;
+ nRetries++;
+ }
+
+ /*
+ * pwritev produces a partial iovec when the disk is
+ * out of space. Just call it an error.
+ */
+
+ if (sum != bytesWritten) {
+ fret = FILEIO_WRITE_ERROR_NOSPC;
+ break;
+ }
+ }
+ return fret;
+}
+
+#endif /* defined(__linux__ ) */
+
+
+#if defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) ||\
+ defined(sun)
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileIO_Preadv --
+ *
+ * Implementation of vector pread.The function checks for the support
+ * of system call preadv with the version of glibc and calls the
+ * optimized system call. If the system call is not supported,
+ * we fall back to the earlier technique of coalescing the vectors
+ * and calling a single pread and decoalescing again.
+ *
+ * Results:
+ * FILEIO_SUCCESS, FILEIO_ERROR
+ *
+ * Side effects:
+ * None
+ *
+ *----------------------------------------------------------------------
+ */
+
+FileIOResult
+FileIO_Preadv(FileIODescriptor *fd, // IN: File descriptor
+ struct iovec *entries, // IN: Vector to read into
+ int numEntries, // IN: Number of vector entries
+ uint64 offset, // IN: Offset to start reading
+ size_t totalSize) // IN: totalSize (bytes) in entries
+{
+ FileIOResult fret;
+
+ ASSERT(fd);
+ ASSERT(entries);
+ ASSERT(!(fd->flags & FILEIO_ASYNCHRONOUS));
+ ASSERT_NOT_IMPLEMENTED(totalSize < 0x80000000);
+
+#if defined(__linux__ )
+ fret = FileIOPreadvInternal(fd, entries, numEntries, offset, totalSize);
+#else
+ fret = FileIOPreadvCoalesced(fd, entries, numEntries, offset, totalSize);
+#endif /* defined(__linux__ ) */
+ return fret;
+}
+
+
+/*
+ *----------------------------------------------------------------------
+ *
+ * FileIO_Pwritev --
+ *
+ * Implementation of vector pwrite.The function checks for the support
+ * of system call pwritev with the version of glibc and calls the
+ * optimized system call. If the system call is not supported,
+ * we fall back to the earlier technique of coalescing the vectors and
+ * calling a single pread and decoalescing again.
+ *
+ * Results:
+ * FILEIO_SUCCESS, FILEIO_ERROR
+ *
+ * Side effects:
+ * None
+ *
+ *----------------------------------------------------------------------
+ */
+
+FileIOResult
+FileIO_Pwritev(FileIODescriptor *fd, // IN: File descriptor
+ struct iovec *entries, // IN: Vector to write from
+ int numEntries, // IN: Number of vector entries
+ uint64 offset, // IN: Offset to start writing
+ size_t totalSize) // IN: Total size (bytes) in entries
+{
+ FileIOResult fret;
+
+ ASSERT(fd);
+ ASSERT(entries);
+ ASSERT(!(fd->flags & FILEIO_ASYNCHRONOUS));
+ ASSERT_NOT_IMPLEMENTED(totalSize < 0x80000000);
+
+#if defined(__linux__ )
+ fret = FileIOPwritevInternal(fd, entries, numEntries, offset, totalSize);
+#else
+ fret = FileIOPwritevCoalesced(fd, entries, numEntries, offset, totalSize);
+#endif /* defined(__linux__ ) */
+ return fret;
+}
+
#endif /* defined(__linux__) || defined(__APPLE__) || defined(__FreeBSD__) ||
defined(sun) */
projects / thirdparty / open-vm-tools.git / commitdiff
