This patch defines an scsi_iovec struct which is guaranteed
to be POSIX compatible. It furthermore adds support for
in+out iovectors for bi-directional operations
Signed-off-by: Peter Lieven <pl@kamp.de>
If an application passes buffers to libiscsi for reading they are
currently added to a linked list one by one. This leads to a malloc
for each buffer object plus O(n) walks trough the list to add
the buffer to then end of the list. Additionally the buffer read
routine takes up to O(n) iterations to find the right buffer
for a request.
This patch introduces an scsi_iovector struct to pass buffers to
an scsi task. Adding a new buffer is in O(1) and finding the
right buffer to also. Malloc requirements are in O(log(n)).
Additionally the scsi_iovector struct is itended to be binary
compatible to an QEMUIOVector allowing to pass this structure
directly to the library.
Initial tests have been made booting an Ubuntu LTS 12.04.1
Desktop server up to the login prompt. The following observations
have been made with regards to scsi_malloc calls:
original implementation: ~11.500 mallocs
using iovector instead of list: ~ 7.500 mallocs
passing the iovector directly: 0 mallocs
To enable this feature in qemu for testing the following patch might
be used:
diff --git a/block/iscsi.c b/block/iscsi.c
index a6a819d..2809c15 100644
--- a/block/iscsi.c
+++ b/block/iscsi.c
@@ -390,11 +390,16 @@ iscsi_aio_readv(BlockDriverState *bs, int64_t sector_num,
return NULL;
}
+#if defined(LIBISCSI_FEATURE_IOVECTOR)
+ assert(sizeof(struct QEMUIOVector) == sizeof(struct scsi_iovector));
+ scsi_iovector_assign(acb->task, (struct scsi_iovector*) acb->qiov);
+#else
for (i = 0; i < acb->qiov->niov; i++) {
scsi_task_add_data_in_buffer(acb->task,
acb->qiov->iov[i].iov_len,
acb->qiov->iov[i].iov_base);
}
+#endif
iscsi_set_events(iscsilun);
---
Signed-off-by: Peter Lieven <pl@kamp.de>
DPRINTF was blindly sending all debug output to fd 2 (stderr).
The new function iscsi_set_debug_fd() will set the debug fd.
In general debugging is completely disabled by default.
qemu-kvm calls iscsi_parse_url_full() with iscsi = NULL.
In case there is an invalid URL specified qemu-kvm segfaults when
it tries to set iscsi->error_string.
I tried to patch this in qemu-kvm, but the initiator_name is dirived
from the target name so this seemed to be the easier approach.
qemu-kvm calls iscsi_parse_url_full() with iscsi = NULL.
In case there is an invalid URL specified qemu-kvm segfaults when
it tries to set iscsi->error_string.
I tried to patch this in qemu-kvm, but the initiator_name is dirived
from the target name so this seemed to be the easier approach.
The iscsi_url and iscsi_context might contain clear text
login credentials for an iscsi target. As Linux zeroes
on allocate this data might remain in memory for a long
time.
This patch adds a wrapper around all memory allocations and frees.
The idea is to get warned immediately if the application leaks memory.
Additionally the wrapper functions make it easy to add different
memory allocators or memory pools in the future.
gcc-4.6.3 reports these:
libtool: compile: gcc -DHAVE_CONFIG_H -I. -I. -I./include "-D_U_=__attribute__((unused))" -Wall -W -Wshadow -Wstrict-prototypes -Wpointer-arith -Wcast-align -Wwrite-strings -g -O2 -MT lib/init.lo -MD -MP -MF lib/.deps/init.Tpo -c lib/init.c -fPIC -DPIC -o lib/.libs/init.o
lib/init.c: In function 'iscsi_parse_url':
lib/init.c:410:18: warning: 'l' may be used uninitialized in this function [-Wuninitialized]
lib/init.c:409:10: warning: 'target' may be used uninitialized in this function [-Wuninitialized]
Both warnings appear to be spurious though, as both "target" and "l" are only used if
"full" is set, which implies that these are initialized before.
Signed-off-by: Arne Redlich <arne.redlich@googlemail.com>
This patch adds support for setting TCP_SYNCNT to overwrite
the system default values. This allows indirect support
for a configurable connect timeout.
Linux uses a exponential backoff for SYN retries starting
with 1 second.
This means for a value n for TCP_SYNCNT, the connect will
effectively timeout after 2^(n+1)-1 seconds.
This patch allows the following parameters inside libiscsi to be adjusted without code modification:
LIBISCSI_DEBUG
LIBISCSI_TCP_USER_TIMEOUT
LIBISCSI_TCP_KEEPIDLE
LIBISCSI_TCP_KEEPCNT
LIBISCSI_TCP_KEEPINTVL
You can now enable debugging of libiscsi inside e.g. qemu-kvm with
LIBISCSI_DEBUG=3 qemu-kvm -hda iscsi://...
This patch adds 3 functions to set the 3 keepalive values TCP_KEEPIDLE, TCP_KEEPCNT
and TCP_KEEPINTVL. The values have to be set after iscsi context creation and are
then configured on the socket on each new connection.
"random" ISID randomly.
Dont assume that users will never create multiple contexts
concurrently, in which case the previous getpid()^time(NULL)
would create duplicates.
