Implement asynchronous readdir
Accessing directories with many (several thousand) files over sshfs is slow, because most SFTP server implementations only send a fixed amount of entries per READDIR command (e.g. OpenSSH SFTP: 100 entries). This patch implements sending several READDIR commands in parallel, in order to speed up directory listing in these cases. An option (sync_readdir) is also added so that users can easily switch on the old behaviour. The performance improvement is astonishing. Accessing a directory with 30k files in from a remote server that has a RTT of 15ms via OpenSSH SFTP: Synchronous readdir: $ ./sshfs -o sync_readdir host:/tmp /mnt/temp $ time "ls" -1 /mnt/temp/test | wc -l 30000 "ls" -1 /mnt/temp/test 0.07s user 0.01s system 1% cpu 6.928 total Asynchronous readdir: $ ./sshfs host:/tmp /mnt/temp $ time "ls" -1 /mnt/temp/test | wc -l 30000 "ls" -1 /mnt/temp/test 0.07s user 0.01s system 12% cpu 0.605 total Accessing a directory with 100k files shows even more dramatic improvement: Synchronous readdir: $ ./sshfs -o sync_readdir host:/tmp /mnt/temp $ time "ls" -1 /mnt/temp/test2 | wc -l 100000 "ls" -1 /mnt/temp/test2 0.67s user 1.22s system 0% cpu 3:31.56 total Asynchronous readdir: $ ./sshfs host:/tmp /mnt/temp $ time "ls" -1 /mnt/temp/test2 | wc -l 100000 "ls" -1 /mnt/temp/test2 0.20s user 0.03s system 14% cpu 1.631 total This can easily be reproduced by creating a directory on a server and touching a lot of files in it: $ mkdir /tmp/test $ cd /tmp/test $ for i in $(seq 1 30000); do touch $i; done Signed-off-by: Alexander Neumann <alexander@bumpern.de>
This commit is contained in:
Alexander Neumann
Miklos Szeredi
parent
334e9e6a27
commit
6a2d06e36f
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@ -3,6 +3,10 @@
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* Add -o disable_hardlink option (debian bug #670926). Reported
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by Louis-David Mitterrand
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* Optimize readdir by sending multiple requests in parallel. Add
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-o sync_readdir to restore old behavior. Patch by Alexander
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Neumann
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2014-01-07 Miklos Szeredi <miklos@szeredi.hu>
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* Map SSH2_FX_FAILURE to ENOTEMPTY for rmdir. Reported by Ross
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3
sshfs.1
3
sshfs.1
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@ -58,6 +58,9 @@ synchronous writes
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\fB\-o\fR no_readahead
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synchronous reads (no speculative readahead)
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.TP
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\fB\-o\fR sync_readdir
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synchronous readdir
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.TP
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\fB\-o\fR sshfs_debug
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print some debugging information
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.TP
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131
sshfs.c
131
sshfs.c
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@ -121,6 +121,10 @@
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#define SSHNODELAY_SO "sshnodelay.so"
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/* Asynchronous readdir parameters */
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#define READDIR_START 2
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#define READDIR_MAX 32
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struct buffer {
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uint8_t *p;
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size_t len;
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@ -139,6 +143,7 @@ struct request {
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unsigned int want_reply;
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sem_t ready;
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uint8_t reply_type;
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uint32_t id;
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int replied;
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int error;
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struct buffer reply;
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@ -215,6 +220,7 @@ struct sshfs {
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unsigned ssh_ver;
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int sync_write;
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int sync_read;
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int sync_readdir;
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int debug;
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int foreground;
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int reconnect;
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@ -351,6 +357,7 @@ static struct fuse_opt sshfs_opts[] = {
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SSHFS_OPT("nomap=error", nomap, NOMAP_ERROR),
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SSHFS_OPT("sshfs_sync", sync_write, 1),
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SSHFS_OPT("no_readahead", sync_read, 1),
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SSHFS_OPT("sync_readdir", sync_readdir, 1),
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SSHFS_OPT("sshfs_debug", debug, 1),
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SSHFS_OPT("reconnect", reconnect, 1),
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SSHFS_OPT("transform_symlinks", transform_symlinks, 1),
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@ -1836,6 +1843,7 @@ static int sftp_request_send(uint8_t type, struct iovec *iov, size_t count,
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if (begin_func)
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begin_func(req);
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id = sftp_get_id();
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req->id = id;
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err = start_processing_thread();
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if (err) {
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pthread_mutex_unlock(&sshfs.lock);
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@ -2023,6 +2031,113 @@ static int sshfs_readlink(const char *path, char *linkbuf, size_t size)
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return err;
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}
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static int sftp_readdir_send(struct request **req, struct buffer *handle)
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{
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struct iovec iov;
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buf_to_iov(handle, &iov);
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return sftp_request_send(SSH_FXP_READDIR, &iov, 1, NULL, NULL,
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SSH_FXP_NAME, NULL, req);
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}
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static int sshfs_req_pending(struct request *req)
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{
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if (g_hash_table_lookup(sshfs.reqtab, GUINT_TO_POINTER(req->id)))
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return 1;
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else
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return 0;
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}
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static int sftp_readdir_async(struct buffer *handle, fuse_cache_dirh_t h,
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fuse_cache_dirfil_t filler)
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{
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int err = 0;
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int outstanding = 0;
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int max = READDIR_START;
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GList *list = NULL;
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int done = 0;
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while (!done || outstanding) {
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struct request *req;
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struct buffer name;
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int tmperr;
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while (!done && outstanding < max) {
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tmperr = sftp_readdir_send(&req, handle);
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if (tmperr && !done) {
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err = tmperr;
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done = 1;
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break;
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}
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list = g_list_append(list, req);
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outstanding++;
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}
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if (outstanding) {
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GList *first;
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/* wait for response to next request */
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first = g_list_first(list);
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req = first->data;
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list = g_list_delete_link(list, first);
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outstanding--;
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if (done) {
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pthread_mutex_lock(&sshfs.lock);
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if (sshfs_req_pending(req))
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req->want_reply = 0;
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pthread_mutex_unlock(&sshfs.lock);
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if (!req->want_reply)
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continue;
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}
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tmperr = sftp_request_wait(req, SSH_FXP_READDIR,
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SSH_FXP_NAME, &name);
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if (tmperr && !done) {
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err = tmperr;
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if (err == MY_EOF)
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err = 0;
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done = 1;
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}
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if (!done) {
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err = buf_get_entries(&name, h, filler);
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buf_free(&name);
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/* increase number of outstanding requests */
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if (max < READDIR_MAX)
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max++;
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if (err)
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done = 1;
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}
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}
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}
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assert(list == NULL);
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return err;
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}
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static int sftp_readdir_sync(struct buffer *handle, fuse_cache_dirh_t h,
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fuse_cache_dirfil_t filler)
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{
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int err;
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do {
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struct buffer name;
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err = sftp_request(SSH_FXP_READDIR, handle, SSH_FXP_NAME, &name);
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if (!err) {
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err = buf_get_entries(&name, h, filler);
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buf_free(&name);
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}
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} while (!err);
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if (err == MY_EOF)
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err = 0;
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return err;
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}
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static int sshfs_getdir(const char *path, fuse_cache_dirh_t h,
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fuse_cache_dirfil_t filler)
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{
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@ -2035,16 +2150,11 @@ static int sshfs_getdir(const char *path, fuse_cache_dirh_t h,
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if (!err) {
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int err2;
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buf_finish(&handle);
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do {
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struct buffer name;
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err = sftp_request(SSH_FXP_READDIR, &handle, SSH_FXP_NAME, &name);
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if (!err) {
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err = buf_get_entries(&name, h, filler);
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buf_free(&name);
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}
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} while (!err);
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if (err == MY_EOF)
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err = 0;
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if (sshfs.sync_readdir)
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err = sftp_readdir_sync(&handle, h, filler);
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else
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err = sftp_readdir_async(&handle, h, filler);
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err2 = sftp_request(SSH_FXP_CLOSE, &handle, 0, NULL);
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if (!err)
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@ -3171,6 +3281,7 @@ static void usage(const char *progname)
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" -o delay_connect delay connection to server\n"
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" -o sshfs_sync synchronous writes\n"
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" -o no_readahead synchronous reads (no speculative readahead)\n"
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" -o sync_readdir synchronous readdir\n"
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" -o sshfs_debug print some debugging information\n"
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" -o cache=BOOL enable caching {yes,no} (default: yes)\n"
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" -o cache_timeout=N sets timeout for caches in seconds (default: 20)\n"
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