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Implement locking with OFD locks when present. #91

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Implement locking with OFD locks when present. #91

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2 changes: 2 additions & 0 deletions configure.ac
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Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,8 @@ AC_CHECK_HEADERS( \
AC_C_BIGENDIAN
AC_C_CONST

AC_CHECK_DECLS([F_OFD_SETLK], [], [], [[#include <fcntl.h>]])

##
# Checks for library functions
##
Expand Down
20 changes: 19 additions & 1 deletion diod/ioctx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,9 @@ struct ioctx_struct {
int refcount;
int fd;
DIR *dir;
#if !HAVE_DECL_F_OFD_SETLK
int lock_type;
#endif
Npqid qid;
u32 iounit;
u32 open_flags;
Expand Down Expand Up @@ -165,7 +167,9 @@ _ioctx_create_open (Npuser *user, Path path, int flags, u32 mode)
}
pthread_mutex_init (&ioctx->lock, NULL);
ioctx->refcount = 1;
#if !HAVE_DECL_F_OFD_SETLK
ioctx->lock_type = LOCK_UN;
#endif
ioctx->dir = NULL;
ioctx->open_flags = flags;
ioctx->user = user;
Expand Down Expand Up @@ -353,6 +357,18 @@ ioctx_fsync(IOCtx ioctx)
return fsync (ioctx->fd);
}

#if HAVE_DECL_F_OFD_SETLK

int
ioctx_fcntl_lock(IOCtx ioctx, int cmd, struct flock *l)
{
if (fcntl(ioctx->fd, cmd, l) < 0)
return -1;
return 0;
}

#else

int
ioctx_flock (IOCtx ioctx, int operation)
{
Expand All @@ -370,7 +386,7 @@ ioctx_flock (IOCtx ioctx, int operation)
/* If lock of 'type' could be obtained, return LOCK_UN, otherwise LOCK_EX.
*/
int
ioctx_testlock (IOCtx ioctx, int type)
ioctx_test_flock (IOCtx ioctx, int type)
{
int ret = LOCK_UN;

Expand Down Expand Up @@ -407,6 +423,8 @@ ioctx_testlock (IOCtx ioctx, int type)
return ret;
}

#endif

u32
ioctx_iounit (IOCtx ioctx)
{
Expand Down
7 changes: 5 additions & 2 deletions diod/ioctx.h
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Original file line number Diff line number Diff line change
Expand Up @@ -28,9 +28,12 @@ struct dirent *ioctx_readdir(IOCtx ioctx, long *new_offset);
void ioctx_rewinddir (IOCtx ioctx);
void ioctx_seekdir (IOCtx ioctx, long offset);
int ioctx_fsync (IOCtx ioctx);
#if HAVE_DECL_F_OFD_SETLK
int ioctx_fcntl_lock(IOCtx ioctx, int cmd, struct flock *l);
#else
int ioctx_flock (IOCtx ioctx, int operation);
int ioctx_testlock (IOCtx ioctx, int operation);

int ioctx_test_flock (IOCtx ioctx, int operation);
#endif
int ioctx_stat (IOCtx ioctx, struct stat *sb);
int ioctx_chmod (IOCtx ioctx, u32 mode);
int ioctx_chown (IOCtx ioctx, u32 uid, u32 gid);
Expand Down
135 changes: 134 additions & 1 deletion diod/ops.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1253,6 +1253,137 @@ diod_fsync (Npfid *fid)
return NULL;
}

#if HAVE_DECL_F_OFD_SETLK

/* Locking note:
* Implement POSIX locks in terms of OFD locks, it will
* at least work for some use cases, but may still deadlock others.
*/

Npfcall*
diod_lock (Npfid *fid, u8 type, u32 flags, u64 start, u64 length, u32 proc_id,
Npstr *client_id)
{
Fid *f = fid->aux;
Npfcall *ret;
u8 status = P9_LOCK_ERROR;
struct flock lock;

if (flags & ~P9_LOCK_FLAGS_BLOCK) { /* only one valid flag for now */
np_uerror (EINVAL); /* (which we ignore) */
goto error;
}
if (!f->ioctx) {
msg ("diod_lock: fid is not open");
np_uerror (EBADF);
goto error;
}

lock.l_whence = SEEK_SET;
lock.l_start = start;
lock.l_len = length;
lock.l_pid = 0;

switch (type) {
case P9_LOCK_TYPE_UNLCK:
lock.l_type = F_UNLCK;
if (ioctx_fcntl_lock(f->ioctx, F_OFD_SETLK, &lock) == 0)
status = P9_LOCK_SUCCESS;
break;
case P9_LOCK_TYPE_RDLCK:
lock.l_type = F_RDLCK;
if (ioctx_fcntl_lock(f->ioctx, F_OFD_SETLK, &lock) == 0)
status = P9_LOCK_SUCCESS;
else if (errno == EWOULDBLOCK)
status = P9_LOCK_BLOCKED;
break;
case P9_LOCK_TYPE_WRLCK:
lock.l_type = F_WRLCK;
if (ioctx_fcntl_lock(f->ioctx, F_OFD_SETLK, &lock) == 0)
status = P9_LOCK_SUCCESS;
else if (errno == EWOULDBLOCK)
status = P9_LOCK_BLOCKED;
break;
default:
np_uerror (EINVAL);
goto error;
}
if (!((ret = np_create_rlock (status)))) {
np_uerror (ENOMEM);
goto error;
}
return ret;
error:
errn (np_rerror (), "diod_lock %s@%s:%s",
fid->user->uname, np_conn_get_client_id (fid->conn),
path_s (f->path));
return NULL;
}

Npfcall*
diod_getlock (Npfid *fid, u8 type, u64 start, u64 length, u32 proc_id,
Npstr *client_id)
{
Fid *f = fid->aux;
Npfcall *ret;
char *cid = NULL;
struct flock lock;

if (!f->ioctx) {
msg ("diod_getlock: fid is not open");
np_uerror (EBADF);
goto error;
}
if (!(cid = np_strdup (client_id))) {
np_uerror (ENOMEM);
goto error;
}
if (type != P9_LOCK_TYPE_RDLCK && type != P9_LOCK_TYPE_WRLCK) {
np_uerror (EINVAL);
goto error;
}

lock.l_whence = SEEK_SET;
lock.l_start = start;
lock.l_len = length;
lock.l_pid = 0;

switch (type) {
case P9_LOCK_TYPE_UNLCK:
lock.l_type = F_UNLCK;
case P9_LOCK_TYPE_RDLCK:
lock.l_type = F_RDLCK;
case P9_LOCK_TYPE_WRLCK:
lock.l_type = F_WRLCK;
default:
np_uerror (EINVAL);
goto error;
}

if (ioctx_fcntl_lock(f->ioctx, F_OFD_GETLK, &lock) != 0) {
np_uerror (errno);
goto error;
}

type = (lock.l_type == F_UNLCK) ? P9_LOCK_TYPE_UNLCK : type;
if (!((ret = np_create_rgetlock(type, start, length, lock.l_pid, cid)))) {
np_uerror (ENOMEM);
goto error;
}
free (cid);
return ret;
error:
errn (np_rerror (), "diod_getlock %s@%s:%s",
fid->user->uname, np_conn_get_client_id (fid->conn),
path_s (f->path));
if (cid)
free (cid);
return NULL;
}

#else


/* Locking note:
* Implement POSIX locks in terms of BSD flock locks.
* This at least gets distributed whole-file locking to work.
Expand Down Expand Up @@ -1331,7 +1462,7 @@ diod_getlock (Npfid *fid, u8 type, u64 start, u64 length, u32 proc_id,
goto error;
}
ftype = (type == P9_LOCK_TYPE_RDLCK) ? LOCK_SH : LOCK_EX;
ftype = ioctx_testlock (f->ioctx, ftype);
ftype = ioctx_test_flock (f->ioctx, ftype);
type = (ftype == LOCK_EX) ? P9_LOCK_TYPE_WRLCK : P9_LOCK_TYPE_UNLCK;
if (!((ret = np_create_rgetlock(type, start, length, proc_id, cid)))) {
np_uerror (ENOMEM);
Expand All @@ -1348,6 +1479,8 @@ diod_getlock (Npfid *fid, u8 type, u64 start, u64 length, u32 proc_id,
return NULL;
}

#endif

Npfcall*
diod_link (Npfid *dfid, Npfid *fid, Npstr *name)
{
Expand Down