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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>
This commit is contained in:
Aneesh Kumar K.V 2011-05-18 15:40:57 +05:30
parent 84dfb926e5
commit 7a46274529
6 changed files with 223 additions and 14 deletions
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4
hw/9pfs/codir.c
View File

@ -100,12 +100,10 @@ int v9fs_co_opendir(V9fsState *s, V9fsFidState *fidp)
return err;
}
int v9fs_co_closedir(V9fsState *s, V9fsFidState *fidp)
int v9fs_co_closedir(V9fsState *s, DIR *dir)
{
int err;
DIR *dir;
dir = fidp->fs.dir;
v9fs_co_run_in_worker(
{
err = s->ops->closedir(&s->ctx, dir);

19
hw/9pfs/cofile.c
View File

@ -58,6 +58,12 @@ int v9fs_co_open(V9fsState *s, V9fsFidState *fidp, int flags)
err = 0;
}
});
if (!err) {
total_open_fd++;
if (total_open_fd > open_fd_hw) {
v9fs_reclaim_fd(s);
}
}
return err;
}
@ -79,15 +85,19 @@ int v9fs_co_open2(V9fsState *s, V9fsFidState *fidp, char *fullname, gid_t gid,
err = -errno;
}
});
if (!err) {
total_open_fd++;
if (total_open_fd > open_fd_hw) {
v9fs_reclaim_fd(s);
}
}
return err;
}
int v9fs_co_close(V9fsState *s, V9fsFidState *fidp)
int v9fs_co_close(V9fsState *s, int fd)
{
int fd;
int err;
fd = fidp->fs.fd;
v9fs_co_run_in_worker(
{
err = s->ops->close(&s->ctx, fd);
@ -95,6 +105,9 @@ int v9fs_co_close(V9fsState *s, V9fsFidState *fidp)
err = -errno;
}
});
if (!err) {
total_open_fd--;
}
return err;
}

4
hw/9pfs/virtio-9p-coth.h
View File

@ -83,8 +83,8 @@ extern int v9fs_co_open2(V9fsState *, V9fsFidState *, char *, gid_t, int, int);
extern int v9fs_co_lsetxattr(V9fsState *, V9fsString *, V9fsString *,
void *, size_t, int);
extern int v9fs_co_lremovexattr(V9fsState *, V9fsString *, V9fsString *);
extern int v9fs_co_closedir(V9fsState *, V9fsFidState *);
extern int v9fs_co_close(V9fsState *, V9fsFidState *);
extern int v9fs_co_closedir(V9fsState *, DIR *);
extern int v9fs_co_close(V9fsState *, int);
extern int v9fs_co_fsync(V9fsState *, V9fsFidState *, int);
extern int v9fs_co_symlink(V9fsState *, V9fsFidState *, const char *,
const char *, gid_t);

1
hw/9pfs/virtio-9p-device.c
View File

@ -171,6 +171,7 @@ static PCIDeviceInfo virtio_9p_info = {
static void virtio_9p_register_devices(void)
{
pci_qdev_register(&virtio_9p_info);
virtio_9p_set_fd_limit();
}
device_init(virtio_9p_register_devices)

187
hw/9pfs/virtio-9p.c
View File

@ -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 size_t v9fs_string_size(V9fsString *str)
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 @@ static V9fsFidState *alloc_fid(V9fsState *s, int32_t fid)
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 @@ static int free_fid(V9fsState *s, V9fsFidState *fidp)
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 @@ static void put_fid(V9fsState *s, V9fsFidState *fidp)
{
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 @@ static int clunk_fid(V9fsState *s, int32_t fid)
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 @@ static void v9fs_open(void *opaque)
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 @@ static void v9fs_lcreate(void *opaque)
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 @@ static void v9fs_create(void *opaque)
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 @@ static void v9fs_remove(void *opaque)
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 @@ void handle_9p_output(VirtIODevice *vdev, VirtQueue *vq)
}
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;
}

22
hw/9pfs/virtio-9p.h
View File

@ -5,6 +5,7 @@
#include <dirent.h>
#include <sys/time.h>
#include <utime.h>
#include <sys/resource.h>
#include "hw/virtio.h"
#include "fsdev/file-op-9p.h"
@ -101,6 +102,9 @@ enum p9_proto_version {
#define P9_NOTAG (u16)(~0)
#define P9_NOFID (u32)(~0)
#define P9_MAXWELEM 16
#define FID_REFERENCED 0x1
#define FID_NON_RECLAIMABLE 0x2
static inline const char *rpath(FsContext *ctx, const char *path, char *buffer)
{
snprintf(buffer, PATH_MAX, "%s/%s", ctx->fs_root, path);
@ -198,14 +202,21 @@ struct V9fsFidState
int32_t fid;
V9fsString path;
union {
int fd;
DIR *dir;
V9fsXattr xattr;
int fd;
DIR *dir;
V9fsXattr xattr;
} fs;
union {
int fd;
DIR *dir;
} fs_reclaim;
int flags;
int open_flags;
uid_t uid;
int ref;
int clunked;
V9fsFidState *next;
V9fsFidState *rclm_lst;
};
typedef struct V9fsState
@ -354,6 +365,9 @@ typedef struct V9fsGetlock
V9fsString client_id;
} V9fsGetlock;
extern int open_fd_hw;
extern int total_open_fd;
size_t pdu_packunpack(void *addr, struct iovec *sg, int sg_count,
size_t offset, size_t size, int pack);
@ -364,4 +378,6 @@ static inline size_t do_pdu_unpack(void *dst, struct iovec *sg, int sg_count,
}
extern void handle_9p_output(VirtIODevice *vdev, VirtQueue *vq);
extern void virtio_9p_set_fd_limit(void);
extern void v9fs_reclaim_fd(V9fsState *s);
#endif