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fixed bug in fallocate usage and avoid trying to allocate and truncate files that don't need it to not update their modification time for no good reason

This commit is contained in:
Arvid Norberg 2010-03-06 20:09:18 +00:00
parent ae8e86e74a
commit 247bd9256d
2 changed files with 42 additions and 22 deletions
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59
src/file.cpp
View File

@ -82,9 +82,14 @@ POSSIBILITY OF SUCH DAMAGE.
static int my_fallocate(int fd, int mode, loff_t offset, loff_t len)
{
#ifdef __NR_fallocate
// the man page on fallocate differes between versions of linux.
// it appears that fallocate in fact sets errno and returns -1
// on failure.
return syscall(__NR_fallocate, fd, mode, offset, len);
#else
return EOPNOTSUPP;
// pretend that the system call doesn't exist
errno = ENOSYS;
return -1;
#endif
}
@ -1464,14 +1469,33 @@ namespace libtorrent
return false;
}
#else
if (ftruncate(m_fd, s) < 0)
struct stat st;
if (fstat(m_fd, &st) != 0)
{
ec.assign(errno, get_posix_category());
return false;
}
if ((m_open_mode & sparse) == 0)
// only truncate the file if it doesn't already
// have the right size. We don't want to update
if (st.st_size != s && ftruncate(m_fd, s) < 0)
{
// if we're not in sparse mode, allocate the storage
ec.assign(errno, get_posix_category());
return false;
}
// if we're not in sparse mode, allocate the storage
// but only if the number of allocated blocks for the file
// is less than the file size. Otherwise we would just
// update the modification time of the file for no good
// reason.
if ((m_open_mode & sparse) == 0
&& st.st_blocks < (s + st.st_blksize - 1) / st.st_blksize)
{
// How do we know that the file is already allocated?
// if we always try to allocate the space, we'll update
// the modification time without actually changing the file
// but if we don't do anything if the file size is
#ifdef F_PREALLOCATE
fstore_t f = {F_ALLOCATECONTIG, F_PEOFPOSMODE, 0, s, 0};
if (fcntl(m_fd, F_PREALLOCATE, &f) < 0)
@ -1481,24 +1505,21 @@ namespace libtorrent
}
#elif defined TORRENT_LINUX
int ret = my_fallocate(m_fd, 0, 0, s);
if (ret == 0 && errno != ENOSYS) return true;
if (ret != EOPNOTSUPP) ec.assign(ret, get_posix_category());
// if fallocate failed, we have to use posix_fallocate
// which can be painfully slow, so only use it if we really
// have to
struct stat st;
if (fstat(m_fd, &st) != 0)
// if we return 0, everything went fine
// the fallocate call succeeded
if (ret == 0) return true;
// otherwise, something went wrong. If the error
// is ENOSYS, just keep going and do it the old-fashioned
// way. If fallocate failed with some other error, it
// probably means the user should know about it, error out
// and report it.
if (errno != ENOSYS)
{
ec.assign(errno, get_posix_category());
ec.assign(ret, get_posix_category());
return false;
}
// if the number of allocated blocks already matches
// the size of the file. No need to allocate it
if (st.st_blocks >= (s + st.st_blksize - 1) / st.st_blksize)
{
ec.clear();
return true;
}
// if fallocate failed, we have to use posix_fallocate
// which can be painfully slow
ret = posix_fallocate(m_fd, 0, s);
if (ret != 0)
{

5
src/storage.cpp
View File

@ -545,12 +545,11 @@ namespace libtorrent
{
ec.clear();
boost::shared_ptr<file> f = open_file(*file_iter, file::read_write, ec);
std::string path = combine_path(m_save_path, file_iter->path);
if (ec) set_error(path, ec);
if (ec) set_error(file_path, ec);
else if (f)
{
f->set_size(file_iter->size, ec);
if (ec) set_error(path, ec);
if (ec) set_error(file_path, ec);
}
}