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authorRavishankar N <ravishankar@redhat.com>2015-06-30 21:10:22 +0300
committerMiklos Szeredi <miklos@szeredi.hu>2015-11-10 12:32:37 +0300
commit0b5da8db145bfd44266ac964a2636a0cf8d7c286 (patch)
tree23e46abfcb58f4b744aeab42a8c3a62e141b399b /fs
parent3ca8138f014a913f98e6ef40e939868e1e9ea876 (diff)
downloadlinux-0b5da8db145bfd44266ac964a2636a0cf8d7c286.tar.xz
fuse: add support for SEEK_HOLE and SEEK_DATA in lseek
A useful performance improvement for accessing virtual machine images via FUSE mount. See https://bugzilla.redhat.com/show_bug.cgi?id=1220173 for a use-case for glusterFS. Signed-off-by: Ravishankar N <ravishankar@redhat.com> Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Diffstat (limited to 'fs')
-rw-r--r--fs/fuse/file.c73
-rw-r--r--fs/fuse/fuse_i.h3
2 files changed, 68 insertions, 8 deletions
diff --git a/fs/fuse/file.c b/fs/fuse/file.c
index 195476a24148..47f181191060 100644
--- a/fs/fuse/file.c
+++ b/fs/fuse/file.c
@@ -2231,20 +2231,77 @@ static sector_t fuse_bmap(struct address_space *mapping, sector_t block)
return err ? 0 : outarg.block;
}
+static loff_t fuse_lseek(struct file *file, loff_t offset, int whence)
+{
+ struct inode *inode = file->f_mapping->host;
+ struct fuse_conn *fc = get_fuse_conn(inode);
+ struct fuse_file *ff = file->private_data;
+ FUSE_ARGS(args);
+ struct fuse_lseek_in inarg = {
+ .fh = ff->fh,
+ .offset = offset,
+ .whence = whence
+ };
+ struct fuse_lseek_out outarg;
+ int err;
+
+ if (fc->no_lseek)
+ goto fallback;
+
+ args.in.h.opcode = FUSE_LSEEK;
+ args.in.h.nodeid = ff->nodeid;
+ args.in.numargs = 1;
+ args.in.args[0].size = sizeof(inarg);
+ args.in.args[0].value = &inarg;
+ args.out.numargs = 1;
+ args.out.args[0].size = sizeof(outarg);
+ args.out.args[0].value = &outarg;
+ err = fuse_simple_request(fc, &args);
+ if (err) {
+ if (err == -ENOSYS) {
+ fc->no_lseek = 1;
+ goto fallback;
+ }
+ return err;
+ }
+
+ return vfs_setpos(file, outarg.offset, inode->i_sb->s_maxbytes);
+
+fallback:
+ err = fuse_update_attributes(inode, NULL, file, NULL);
+ if (!err)
+ return generic_file_llseek(file, offset, whence);
+ else
+ return err;
+}
+
static loff_t fuse_file_llseek(struct file *file, loff_t offset, int whence)
{
loff_t retval;
struct inode *inode = file_inode(file);
- /* No i_mutex protection necessary for SEEK_CUR and SEEK_SET */
- if (whence == SEEK_CUR || whence == SEEK_SET)
- return generic_file_llseek(file, offset, whence);
-
- mutex_lock(&inode->i_mutex);
- retval = fuse_update_attributes(inode, NULL, file, NULL);
- if (!retval)
+ switch (whence) {
+ case SEEK_SET:
+ case SEEK_CUR:
+ /* No i_mutex protection necessary for SEEK_CUR and SEEK_SET */
retval = generic_file_llseek(file, offset, whence);
- mutex_unlock(&inode->i_mutex);
+ break;
+ case SEEK_END:
+ mutex_lock(&inode->i_mutex);
+ retval = fuse_update_attributes(inode, NULL, file, NULL);
+ if (!retval)
+ retval = generic_file_llseek(file, offset, whence);
+ mutex_unlock(&inode->i_mutex);
+ break;
+ case SEEK_HOLE:
+ case SEEK_DATA:
+ mutex_lock(&inode->i_mutex);
+ retval = fuse_lseek(file, offset, whence);
+ mutex_unlock(&inode->i_mutex);
+ break;
+ default:
+ retval = -EINVAL;
+ }
return retval;
}
diff --git a/fs/fuse/fuse_i.h b/fs/fuse/fuse_i.h
index 405113101db8..ce394b5fe6b4 100644
--- a/fs/fuse/fuse_i.h
+++ b/fs/fuse/fuse_i.h
@@ -605,6 +605,9 @@ struct fuse_conn {
/** Does the filesystem support asynchronous direct-IO submission? */
unsigned async_dio:1;
+ /** Is lseek not implemented by fs? */
+ unsigned no_lseek:1;
+
/** The number of requests waiting for completion */
atomic_t num_waiting;