| Message ID | 20180214204915.7980-3-mreitz@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 02/14/2018 02:49 PM, Max Reitz wrote: > At runtime (that is, during a future ssh_truncate()), the SSH session is > non-blocking. However, ssh_truncate() (or rather, bdrv_truncate() in > general) is not a coroutine, so this resize operation needs to block. > > For ssh_create(), that is fine, too; the session is never set to > non-blocking anyway. > > Signed-off-by: Max Reitz <mreitz@redhat.com> > --- > block/ssh.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/block/ssh.c b/block/ssh.c > index 964e55f7fe..ff8576f21e 100644 > --- a/block/ssh.c > +++ b/block/ssh.c > @@ -803,17 +803,24 @@ static int ssh_file_open(BlockDriverState *bs, QDict *options, int bdrv_flags, > return ret; > } > > +/* Note: This is a blocking operation */ > static int ssh_grow_file(BDRVSSHState *s, int64_t offset, Error **errp) > { > ssize_t ret; > char c[1] = { '\0' }; > + int was_blocking = libssh2_session_get_blocking(s->session); > > /* offset must be strictly greater than the current size so we do > * not overwrite anything */ > assert(offset > 0 && offset > s->attrs.filesize); > > + libssh2_session_set_blocking(s->session, 1); > + > libssh2_sftp_seek64(s->sftp_handle, offset - 1); > ret = libssh2_sftp_write(s->sftp_handle, c, 1); > + > + libssh2_session_set_blocking(s->session, was_blocking); Is it worth skipping the two libssh2_session_set_blocking() calls if was_blocking is 1? But that's a micro-optimization that probably won't be noticeable, so I'm also fine with unconditional. Reviewed-by: Eric Blake <eblake@redhat.com>
On 2018-02-14 22:11, Eric Blake wrote: > On 02/14/2018 02:49 PM, Max Reitz wrote: >> At runtime (that is, during a future ssh_truncate()), the SSH session is >> non-blocking. However, ssh_truncate() (or rather, bdrv_truncate() in >> general) is not a coroutine, so this resize operation needs to block. >> >> For ssh_create(), that is fine, too; the session is never set to >> non-blocking anyway. >> >> Signed-off-by: Max Reitz <mreitz@redhat.com> >> --- >> block/ssh.c | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/block/ssh.c b/block/ssh.c >> index 964e55f7fe..ff8576f21e 100644 >> --- a/block/ssh.c >> +++ b/block/ssh.c >> @@ -803,17 +803,24 @@ static int ssh_file_open(BlockDriverState *bs, >> QDict *options, int bdrv_flags, >> return ret; >> } >> +/* Note: This is a blocking operation */ >> static int ssh_grow_file(BDRVSSHState *s, int64_t offset, Error **errp) >> { >> ssize_t ret; >> char c[1] = { '\0' }; >> + int was_blocking = libssh2_session_get_blocking(s->session); >> /* offset must be strictly greater than the current size so we do >> * not overwrite anything */ >> assert(offset > 0 && offset > s->attrs.filesize); >> + libssh2_session_set_blocking(s->session, 1); >> + >> libssh2_sftp_seek64(s->sftp_handle, offset - 1); >> ret = libssh2_sftp_write(s->sftp_handle, c, 1); >> + >> + libssh2_session_set_blocking(s->session, was_blocking); > > Is it worth skipping the two libssh2_session_set_blocking() calls if > was_blocking is 1? But that's a micro-optimization that probably won't > be noticeable, so I'm also fine with unconditional. I was hoping libssh2 is clever enough for that itself. :-) > Reviewed-by: Eric Blake <eblake@redhat.com> Thanks! Max
diff --git a/block/ssh.c b/block/ssh.c index 964e55f7fe..ff8576f21e 100644 --- a/block/ssh.c +++ b/block/ssh.c @@ -803,17 +803,24 @@ static int ssh_file_open(BlockDriverState *bs, QDict *options, int bdrv_flags, return ret; } +/* Note: This is a blocking operation */ static int ssh_grow_file(BDRVSSHState *s, int64_t offset, Error **errp) { ssize_t ret; char c[1] = { '\0' }; + int was_blocking = libssh2_session_get_blocking(s->session); /* offset must be strictly greater than the current size so we do * not overwrite anything */ assert(offset > 0 && offset > s->attrs.filesize); + libssh2_session_set_blocking(s->session, 1); + libssh2_sftp_seek64(s->sftp_handle, offset - 1); ret = libssh2_sftp_write(s->sftp_handle, c, 1); + + libssh2_session_set_blocking(s->session, was_blocking); + if (ret < 0) { sftp_error_setg(errp, s, "Failed to grow file"); return -EIO;
At runtime (that is, during a future ssh_truncate()), the SSH session is non-blocking. However, ssh_truncate() (or rather, bdrv_truncate() in general) is not a coroutine, so this resize operation needs to block. For ssh_create(), that is fine, too; the session is never set to non-blocking anyway. Signed-off-by: Max Reitz <mreitz@redhat.com> --- block/ssh.c | 7 +++++++ 1 file changed, 7 insertions(+)