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ceph: Provide a splice-read wrapper

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Provide a splice_read wrapper for Ceph.  This does the inode shutdown check
before proceeding and jumps to copy_splice_read() if the file has inline
data or is a synchronous file.

We try and get FILE_RD and either FILE_CACHE and/or FILE_LAZYIO caps and
hold them across filemap_splice_read().  If we fail to get FILE_CACHE or
FILE_LAZYIO capabilities, we use copy_splice_read() instead.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Xiubo Li <xiubli@redhat.com>
cc: Christoph Hellwig <hch@lst.de>
cc: Al Viro <viro@zeniv.linux.org.uk>
cc: Jens Axboe <axboe@kernel.dk>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: ceph-devel@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-block@vger.kernel.org
cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/20230522135018.2742245-17-dhowells@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
David Howells 2023-05-22 14:50:03 +01:00 committed by Jens Axboe
parent d96d96eebb
commit ccfdf7cbb5
1 changed files with 64 additions and 1 deletions
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65
fs/ceph/file.c
View File

@ -1745,6 +1745,69 @@ again:
return ret;
}
/*
* Wrap filemap_splice_read with checks for cap bits on the inode.
* Atomically grab references, so that those bits are not released
* back to the MDS mid-read.
*/
static ssize_t ceph_splice_read(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe,
size_t len, unsigned int flags)
{
struct ceph_file_info *fi = in->private_data;
struct inode *inode = file_inode(in);
struct ceph_inode_info *ci = ceph_inode(inode);
ssize_t ret;
int want = 0, got = 0;
CEPH_DEFINE_RW_CONTEXT(rw_ctx, 0);
dout("splice_read %p %llx.%llx %llu~%zu trying to get caps on %p\n",
inode, ceph_vinop(inode), *ppos, len, inode);
if (ceph_inode_is_shutdown(inode))
return -ESTALE;
if (ceph_has_inline_data(ci) ||
(fi->flags & CEPH_F_SYNC))
return copy_splice_read(in, ppos, pipe, len, flags);
ceph_start_io_read(inode);
want = CEPH_CAP_FILE_CACHE;
if (fi->fmode & CEPH_FILE_MODE_LAZY)
want |= CEPH_CAP_FILE_LAZYIO;
ret = ceph_get_caps(in, CEPH_CAP_FILE_RD, want, -1, &got);
if (ret < 0)
goto out_end;
if ((got & (CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO)) == 0) {
dout("splice_read/sync %p %llx.%llx %llu~%zu got cap refs on %s\n",
inode, ceph_vinop(inode), *ppos, len,
ceph_cap_string(got));
ceph_put_cap_refs(ci, got);
ceph_end_io_read(inode);
return copy_splice_read(in, ppos, pipe, len, flags);
}
dout("splice_read %p %llx.%llx %llu~%zu got cap refs on %s\n",
inode, ceph_vinop(inode), *ppos, len, ceph_cap_string(got));
rw_ctx.caps = got;
ceph_add_rw_context(fi, &rw_ctx);
ret = filemap_splice_read(in, ppos, pipe, len, flags);
ceph_del_rw_context(fi, &rw_ctx);
dout("splice_read %p %llx.%llx dropping cap refs on %s = %zd\n",
inode, ceph_vinop(inode), ceph_cap_string(got), ret);
ceph_put_cap_refs(ci, got);
out_end:
ceph_end_io_read(inode);
return ret;
}
/*
* Take cap references to avoid releasing caps to MDS mid-write.
*
@ -2593,7 +2656,7 @@ const struct file_operations ceph_file_fops = {
.lock = ceph_lock,
.setlease = simple_nosetlease,
.flock = ceph_flock,
.splice_read = generic_file_splice_read,
.splice_read = ceph_splice_read,
.splice_write = iter_file_splice_write,
.unlocked_ioctl = ceph_ioctl,
.compat_ioctl = compat_ptr_ioctl,