hw/9pfs: Add file descriptor reclaim support
[M. Mohan Kumar <mohan@in.ibm.com> removed some unused variables]
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
diff --git a/hw/9pfs/virtio-9p.c b/hw/9pfs/virtio-9p.c
index 555f456..4ba2590 100644
--- a/hw/9pfs/virtio-9p.c
+++ b/hw/9pfs/virtio-9p.c
@@ -22,6 +22,9 @@
#include "virtio-9p-coth.h"
int debug_9p_pdu;
+int open_fd_hw;
+int total_open_fd;
+static int open_fd_rc;
enum {
Oread = 0x00,
@@ -234,12 +237,41 @@
static V9fsFidState *get_fid(V9fsState *s, int32_t fid)
{
+ int err;
V9fsFidState *f;
for (f = s->fid_list; f; f = f->next) {
BUG_ON(f->clunked);
if (f->fid == fid) {
+ /*
+ * Update the fid ref upfront so that
+ * we don't get reclaimed when we yield
+ * in open later.
+ */
f->ref++;
+
+ /*
+ * check whether we need to reopen the
+ * file. We might have closed the fd
+ * while trying to free up some file
+ * descriptors.
+ */
+ if (f->fid_type == P9_FID_FILE) {
+ if (f->fs.fd == -1) {
+ do {
+ err = v9fs_co_open(s, f, f->open_flags);
+ } while (err == -EINTR);
+ if (err < 0) {
+ f->ref--;
+ return NULL;
+ }
+ }
+ }
+ /*
+ * Mark the fid as referenced so that the LRU
+ * reclaim won't close the file descriptor
+ */
+ f->flags |= FID_REFERENCED;
return f;
}
}
@@ -261,6 +293,11 @@
f->fid = fid;
f->fid_type = P9_FID_NONE;
f->ref = 1;
+ /*
+ * Mark the fid as referenced so that the LRU
+ * reclaim won't close the file descriptor
+ */
+ f->flags |= FID_REFERENCED;
f->next = s->fid_list;
s->fid_list = f;
@@ -306,9 +343,12 @@
int retval = 0;
if (fidp->fid_type == P9_FID_FILE) {
- retval = v9fs_co_close(s, fidp);
+ /* If we reclaimed the fd no need to close */
+ if (fidp->fs.fd != -1) {
+ retval = v9fs_co_close(s, fidp->fs.fd);
+ }
} else if (fidp->fid_type == P9_FID_DIR) {
- retval = v9fs_co_closedir(s, fidp);
+ retval = v9fs_co_closedir(s, fidp->fs.dir);
} else if (fidp->fid_type == P9_FID_XATTR) {
retval = v9fs_xattr_fid_clunk(s, fidp);
}
@@ -321,6 +361,9 @@
{
BUG_ON(!fidp->ref);
fidp->ref--;
+ /*
+ * Don't free the fid if it is in reclaim list
+ */
if (!fidp->ref && fidp->clunked) {
free_fid(s, fidp);
}
@@ -345,6 +388,101 @@
return 0;
}
+void v9fs_reclaim_fd(V9fsState *s)
+{
+ int reclaim_count = 0;
+ V9fsFidState *f, *reclaim_list = NULL;
+
+ for (f = s->fid_list; f; f = f->next) {
+ /*
+ * Unlink fids cannot be reclaimed. Check
+ * for them and skip them. Also skip fids
+ * currently being operated on.
+ */
+ if (f->ref || f->flags & FID_NON_RECLAIMABLE) {
+ continue;
+ }
+ /*
+ * if it is a recently referenced fid
+ * we leave the fid untouched and clear the
+ * reference bit. We come back to it later
+ * in the next iteration. (a simple LRU without
+ * moving list elements around)
+ */
+ if (f->flags & FID_REFERENCED) {
+ f->flags &= ~FID_REFERENCED;
+ continue;
+ }
+ /*
+ * Add fids to reclaim list.
+ */
+ if (f->fid_type == P9_FID_FILE) {
+ if (f->fs.fd != -1) {
+ /*
+ * Up the reference count so that
+ * a clunk request won't free this fid
+ */
+ f->ref++;
+ f->rclm_lst = reclaim_list;
+ reclaim_list = f;
+ f->fs_reclaim.fd = f->fs.fd;
+ f->fs.fd = -1;
+ reclaim_count++;
+ }
+ }
+ if (reclaim_count >= open_fd_rc) {
+ break;
+ }
+ }
+ /*
+ * Now close the fid in reclaim list. Free them if they
+ * are already clunked.
+ */
+ while (reclaim_list) {
+ f = reclaim_list;
+ reclaim_list = f->rclm_lst;
+ if (f->fid_type == P9_FID_FILE) {
+ v9fs_co_close(s, f->fs_reclaim.fd);
+ }
+ f->rclm_lst = NULL;
+ /*
+ * Now drop the fid reference, free it
+ * if clunked.
+ */
+ put_fid(s, f);
+ }
+}
+
+static int v9fs_mark_fids_unreclaim(V9fsState *s, V9fsString *str)
+{
+ int err;
+ V9fsFidState *fidp, head_fid;
+
+ head_fid.next = s->fid_list;
+ for (fidp = s->fid_list; fidp; fidp = fidp->next) {
+ if (!strcmp(fidp->path.data, str->data)) {
+ /* Mark the fid non reclaimable. */
+ fidp->flags |= FID_NON_RECLAIMABLE;
+ /* reopen the file if already closed */
+ if (fidp->fs.fd == -1) {
+ do {
+ err = v9fs_co_open(s, fidp, fidp->open_flags);
+ } while (err == -EINTR);
+ if (err < 0) {
+ return -1;
+ }
+ /*
+ * Go back to head of fid list because
+ * the list could have got updated when
+ * switched to the worker thread
+ */
+ fidp = &head_fid;
+ }
+ }
+ }
+ return 0;
+}
+
#define P9_QID_TYPE_DIR 0x80
#define P9_QID_TYPE_SYMLINK 0x02
@@ -1389,6 +1527,14 @@
goto out;
}
fidp->fid_type = P9_FID_FILE;
+ fidp->open_flags = flags;
+ if (flags & O_EXCL) {
+ /*
+ * We let the host file system do O_EXCL check
+ * We should not reclaim such fd
+ */
+ fidp->flags |= FID_NON_RECLAIMABLE;
+ }
iounit = get_iounit(s, &fidp->path);
offset += pdu_marshal(pdu, offset, "Qd", &qid, iounit);
err = offset;
@@ -1432,6 +1578,14 @@
goto out;
}
fidp->fid_type = P9_FID_FILE;
+ fidp->open_flags = flags;
+ if (flags & O_EXCL) {
+ /*
+ * We let the host file system do O_EXCL check
+ * We should not reclaim such fd
+ */
+ fidp->flags |= FID_NON_RECLAIMABLE;
+ }
iounit = get_iounit(pdu->s, &fullname);
err = v9fs_co_lstat(pdu->s, &fullname, &stbuf);
@@ -1993,6 +2147,14 @@
goto out;
}
fidp->fid_type = P9_FID_FILE;
+ fidp->open_flags = omode_to_uflags(mode);
+ if (fidp->open_flags & O_EXCL) {
+ /*
+ * We let the host file system do O_EXCL check
+ * We should not reclaim such fd
+ */
+ fidp->flags |= FID_NON_RECLAIMABLE;
+ }
}
err = v9fs_co_lstat(pdu->s, &fullname, &stbuf);
if (err < 0) {
@@ -2124,11 +2286,19 @@
err = -EINVAL;
goto out_nofid;
}
+ /*
+ * IF the file is unlinked, we cannot reopen
+ * the file later. So don't reclaim fd
+ */
+ err = v9fs_mark_fids_unreclaim(pdu->s, &fidp->path);
+ if (err < 0) {
+ goto out_err;
+ }
err = v9fs_co_remove(pdu->s, &fidp->path);
if (!err) {
err = offset;
}
-
+out_err:
/* For TREMOVE we need to clunk the fid even on failed remove */
clunk_fid(pdu->s, fidp->fid);
put_fid(pdu->s, fidp);
@@ -2823,3 +2993,14 @@
}
free_pdu(s, pdu);
}
+
+void virtio_9p_set_fd_limit(void)
+{
+ struct rlimit rlim;
+ if (getrlimit(RLIMIT_NOFILE, &rlim) < 0) {
+ fprintf(stderr, "Failed to get the resource limit\n");
+ exit(1);
+ }
+ open_fd_hw = rlim.rlim_cur - MIN(400, rlim.rlim_cur/3);
+ open_fd_rc = rlim.rlim_cur/2;
+}
