Re: [RFC PATCH 33/35] ceph: Use netfslib [INCOMPLETE]

From: Viacheslav Dubeyko
Date: Wed Mar 19 2025 - 15:55:41 EST

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On Thu, 2025-03-13 at 23:33 +0000, David Howells wrote:
> Implement netfslib support for ceph.
>
> Note that I've put the new code into its own file for now rather than
> attempting to modify the old code or putting it into an existing file. The
> old code is just #if'd out for removal in a subsequent patch to make this
> patch easier to review.
>
> Note also that this is incomplete as sparse map support and content crypto
> support are currently non-functional - but plain I/O should work.
>
> There may also be an inode ref leak due to the way the ceph sometimes takes
> and holds on to an extra inode ref under some circumstances. I'm not sure
> these are actually necessary. For instance, ceph_dirty_folio() will ihold
> the inode if ci->i_wrbuffer_ref is 0
>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> cc: Viacheslav Dubeyko <slava@xxxxxxxxxxx>
> cc: Alex Markuze <amarkuze@xxxxxxxxxx>
> cc: Ilya Dryomov <idryomov@xxxxxxxxx>
> cc: ceph-devel@xxxxxxxxxxxxxxx
> cc: linux-fsdevel@xxxxxxxxxxxxxxx
> ---
> drivers/block/rbd.c | 2 +-
> fs/ceph/Makefile | 2 +-
> fs/ceph/addr.c | 46 +-
> fs/ceph/cache.h | 5 +
> fs/ceph/caps.c | 2 +-
> fs/ceph/crypto.c | 54 ++
> fs/ceph/file.c | 15 +-
> fs/ceph/inode.c | 30 +-
> fs/ceph/rdwr.c | 1006 +++++++++++++++++++++++++++++++
> fs/ceph/super.h | 39 +-
> fs/netfs/internal.h | 6 +-
> fs/netfs/main.c | 4 +-
> fs/netfs/write_issue.c | 6 +-
> include/linux/ceph/libceph.h | 3 +-
> include/linux/ceph/osd_client.h | 1 +
> include/linux/netfs.h | 13 +-
> net/ceph/snapshot.c | 20 +-
> 17 files changed, 1190 insertions(+), 64 deletions(-)
> create mode 100644 fs/ceph/rdwr.c
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index 956fc4a8f1da..94bb29c95b0d 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -468,7 +468,7 @@ static DEFINE_IDA(rbd_dev_id_ida);
> static struct workqueue_struct *rbd_wq;
>
> static struct ceph_snap_context rbd_empty_snapc = {
> - .nref = REFCOUNT_INIT(1),
> + .group.ref = REFCOUNT_INIT(1),
> };
>
> /*
> diff --git a/fs/ceph/Makefile b/fs/ceph/Makefile
> index 1f77ca04c426..e4d3c2d6e9c2 100644
> --- a/fs/ceph/Makefile
> +++ b/fs/ceph/Makefile
> @@ -5,7 +5,7 @@
>
> obj-$(CONFIG_CEPH_FS) += ceph.o
>
> -ceph-y := super.o inode.o dir.o file.o locks.o addr.o ioctl.o \
> +ceph-y := super.o inode.o dir.o file.o locks.o addr.o rdwr.o ioctl.o \
> export.o caps.o snap.o xattr.o quota.o io.o \
> mds_client.o mdsmap.o strings.o ceph_frag.o \
> debugfs.o util.o metric.o
> diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
> index 27f27ab24446..325fbbce1eaa 100644
> --- a/fs/ceph/addr.c
> +++ b/fs/ceph/addr.c
> @@ -64,27 +64,30 @@
> (CONGESTION_ON_THRESH(congestion_kb) - \
> (CONGESTION_ON_THRESH(congestion_kb) >> 2))
>
> +#if 0 // TODO: Remove after netfs conversion
> static int ceph_netfs_check_write_begin(struct file *file, loff_t pos, unsigned int len,
> struct folio **foliop, void **_fsdata);
>
> -static inline struct ceph_snap_context *page_snap_context(struct page *page)
> +static struct ceph_snap_context *page_snap_context(struct page *page)
> {
> if (PagePrivate(page))
> return (void *)page->private;
> return NULL;
> }
> +#endif // TODO: Remove after netfs conversion
>
> /*
> * Dirty a page. Optimistically adjust accounting, on the assumption
> * that we won't race with invalidate. If we do, readjust.
> */
> -static bool ceph_dirty_folio(struct address_space *mapping, struct folio *folio)
> +bool ceph_dirty_folio(struct address_space *mapping, struct folio *folio)
> {
> struct inode *inode = mapping->host;
> struct ceph_client *cl = ceph_inode_to_client(inode);
> struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
> struct ceph_inode_info *ci;
> struct ceph_snap_context *snapc;
> + struct netfs_group *group;
>
> if (folio_test_dirty(folio)) {
> doutc(cl, "%llx.%llx %p idx %lu -- already dirty\n",
> @@ -101,16 +104,28 @@ static bool ceph_dirty_folio(struct address_space *mapping, struct folio *folio)
> spin_lock(&ci->i_ceph_lock);
> if (__ceph_have_pending_cap_snap(ci)) {
> struct ceph_cap_snap *capsnap =
> - list_last_entry(&ci->i_cap_snaps,
> - struct ceph_cap_snap,
> - ci_item);
> - snapc = ceph_get_snap_context(capsnap->context);
> + list_last_entry(&ci->i_cap_snaps,
> + struct ceph_cap_snap,
> + ci_item);
> + snapc = capsnap->context;
> capsnap->dirty_pages++;
> } else {
> - BUG_ON(!ci->i_head_snapc);
> - snapc = ceph_get_snap_context(ci->i_head_snapc);
> + snapc = ci->i_head_snapc;
> + BUG_ON(!snapc);
> ++ci->i_wrbuffer_ref_head;
> }
> +
> + /* Attach a reference to the snap/group to the folio. */
> + group = netfs_folio_group(folio);
> + if (group != &snapc->group) {
> + netfs_set_group(folio, &snapc->group);
> + if (group) {
> + doutc(cl, "Different group %px != %px\n",

Do we really need to use %px?

> + group, &snapc->group);
> + netfs_put_group(group);
> + }
> + }
> +
> if (ci->i_wrbuffer_ref == 0)
> ihold(inode);
> ++ci->i_wrbuffer_ref;
> @@ -122,16 +137,10 @@ static bool ceph_dirty_folio(struct address_space *mapping, struct folio *folio)
> snapc, snapc->seq, snapc->num_snaps);
> spin_unlock(&ci->i_ceph_lock);
>
> - /*
> - * Reference snap context in folio->private. Also set
> - * PagePrivate so that we get invalidate_folio callback.
> - */
> - VM_WARN_ON_FOLIO(folio->private, folio);
> - folio_attach_private(folio, snapc);
> -
> - return ceph_fscache_dirty_folio(mapping, folio);
> + return netfs_dirty_folio(mapping, folio);
> }
>
> +#if 0 // TODO: Remove after netfs conversion
> /*
> * If we are truncating the full folio (i.e. offset == 0), adjust the
> * dirty folio counters appropriately. Only called if there is private
> @@ -1236,6 +1245,7 @@ bool is_num_ops_too_big(struct ceph_writeback_ctl *ceph_wbc)
> return ceph_wbc->num_ops >=
> (ceph_wbc->from_pool ? CEPH_OSD_SLAB_OPS : CEPH_OSD_MAX_OPS);
> }
> +#endif // TODO: Remove after netfs conversion
>
> static inline
> bool is_write_congestion_happened(struct ceph_fs_client *fsc)
> @@ -1244,6 +1254,7 @@ bool is_write_congestion_happened(struct ceph_fs_client *fsc)
> CONGESTION_ON_THRESH(fsc->mount_options->congestion_kb);
> }
>
> +#if 0 // TODO: Remove after netfs conversion
> static inline int move_dirty_folio_in_page_array(struct address_space *mapping,
> struct writeback_control *wbc,
> struct ceph_writeback_ctl *ceph_wbc, struct folio *folio)
> @@ -1930,6 +1941,7 @@ const struct address_space_operations ceph_aops = {
> .direct_IO = noop_direct_IO,
> .migrate_folio = filemap_migrate_folio,
> };
> +#endif // TODO: Remove after netfs conversion
>
> static void ceph_block_sigs(sigset_t *oldset)
> {
> @@ -2034,6 +2046,7 @@ static vm_fault_t ceph_filemap_fault(struct vm_fault *vmf)
> return ret;
> }
>
> +#if 0 // TODO: Remove after netfs conversion
> static vm_fault_t ceph_page_mkwrite(struct vm_fault *vmf)
> {
> struct vm_area_struct *vma = vmf->vma;
> @@ -2137,6 +2150,7 @@ static vm_fault_t ceph_page_mkwrite(struct vm_fault *vmf)
> ret = vmf_error(err);
> return ret;
> }
> +#endif // TODO: Remove after netfs conversion
>
> void ceph_fill_inline_data(struct inode *inode, struct page *locked_page,
> char *data, size_t len)
> diff --git a/fs/ceph/cache.h b/fs/ceph/cache.h
> index 20efac020394..d6afca292f08 100644
> --- a/fs/ceph/cache.h
> +++ b/fs/ceph/cache.h
> @@ -43,6 +43,8 @@ static inline void ceph_fscache_resize(struct inode *inode, loff_t to)
> }
> }
>
> +#if 0 // TODO: Remove after netfs conversion
> +
> static inline int ceph_fscache_unpin_writeback(struct inode *inode,
> struct writeback_control *wbc)
> {
> @@ -50,6 +52,7 @@ static inline int ceph_fscache_unpin_writeback(struct inode *inode,
> }
>
> #define ceph_fscache_dirty_folio netfs_dirty_folio
> +#endif // TODO: Remove after netfs conversion
>
> static inline bool ceph_is_cache_enabled(struct inode *inode)
> {
> @@ -100,6 +103,7 @@ static inline void ceph_fscache_resize(struct inode *inode, loff_t to)
> {
> }
>
> +#if 0 // TODO: Remove after netfs conversion
> static inline int ceph_fscache_unpin_writeback(struct inode *inode,
> struct writeback_control *wbc)
> {
> @@ -107,6 +111,7 @@ static inline int ceph_fscache_unpin_writeback(struct inode *inode,
> }
>
> #define ceph_fscache_dirty_folio filemap_dirty_folio
> +#endif // TODO: Remove after netfs conversion
>
> static inline bool ceph_is_cache_enabled(struct inode *inode)
> {
> diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c
> index a8d8b56cf9d2..53f23f351003 100644
> --- a/fs/ceph/caps.c
> +++ b/fs/ceph/caps.c
> @@ -2536,7 +2536,7 @@ int ceph_write_inode(struct inode *inode, struct writeback_control *wbc)
> int wait = (wbc->sync_mode == WB_SYNC_ALL && !wbc->for_sync);
>
> doutc(cl, "%p %llx.%llx wait=%d\n", inode, ceph_vinop(inode), wait);
> - ceph_fscache_unpin_writeback(inode, wbc);
> + netfs_unpin_writeback(inode, wbc);
> if (wait) {
> err = ceph_wait_on_async_create(inode);
> if (err)
> diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c
> index a28dea74ca6f..8d4e908da7d8 100644
> --- a/fs/ceph/crypto.c
> +++ b/fs/ceph/crypto.c
> @@ -636,6 +636,60 @@ int ceph_fscrypt_decrypt_extents(struct inode *inode, struct page **page,
> return ret;
> }
>
> +#if 0
> +int ceph_decrypt_block(struct netfs_io_request *rreq, loff_t pos, size_t len,
> + struct scatterlist *source_sg, unsigned int n_source,
> + struct scatterlist *dest_sg, unsigned int n_dest)
> +{
> + struct ceph_sparse_extent *map = op->extent.sparse_ext;
> + struct ceph_inode_info *ci = ceph_inode(inode);
> + size_t xlen;
> + u64 objno, objoff;
> + u32 ext_cnt = op->extent.sparse_ext_cnt;
> + int i, ret = 0;
> +
> + /* Nothing to do for empty array */
> + if (ext_cnt == 0) {
> + dout("%s: empty array, ret 0\n", __func__);

Yeah, I always would like to see the function name during the debugging the
code. Maybe, do we need to change dout() itself to show the function name?

> + return 0;
> + }
> +
> + ceph_calc_file_object_mapping(&ci->i_layout, pos, map[0].len,
> + &objno, &objoff, &xlen);
> +
> + for (i = 0; i < ext_cnt; ++i) {
> + struct ceph_sparse_extent *ext = &map[i];
> + int pgsoff = ext->off - objoff;
> + int pgidx = pgsoff >> PAGE_SHIFT;
> + int fret;
> +
> + if ((ext->off | ext->len) & ~CEPH_FSCRYPT_BLOCK_MASK) {
> + pr_warn("%s: bad encrypted sparse extent idx %d off %llx len %llx\n",
> + __func__, i, ext->off, ext->len);
> + return -EIO;
> + }
> + fret = ceph_fscrypt_decrypt_pages(inode, &page[pgidx],
> + off + pgsoff, ext->len);
> + dout("%s: [%d] 0x%llx~0x%llx fret %d\n", __func__, i,
> + ext->off, ext->len, fret);
> + if (fret < 0) {

Possibly, I am missing some logic here. But do we really need to introduce fret?
Why we cannot user ret here?

> + if (ret == 0)
> + ret = fret;
> + break;
> + }
> + ret = pgsoff + fret;
> + }
> + dout("%s: ret %d\n", __func__, ret);
> + return ret;
> +}
> +
> +int ceph_encrypt_block(struct netfs_io_request *wreq, loff_t pos, size_t len,
> + struct scatterlist *source_sg, unsigned int n_source,
> + struct scatterlist *dest_sg, unsigned int n_dest)
> +{
> +}
> +#endif
> +
> /**
> * ceph_fscrypt_encrypt_pages - encrypt an array of pages
> * @inode: pointer to inode associated with these pages
> diff --git a/fs/ceph/file.c b/fs/ceph/file.c
> index 4512215cccc6..94b91b5bc843 100644
> --- a/fs/ceph/file.c
> +++ b/fs/ceph/file.c
> @@ -77,6 +77,7 @@ static __le32 ceph_flags_sys2wire(struct ceph_mds_client *mdsc, u32 flags)
> * need to wait for MDS acknowledgement.
> */
>
> +#if 0 // TODO: Remove after netfs conversion
> /*
> * How many pages to get in one call to iov_iter_get_pages(). This
> * determines the size of the on-stack array used as a buffer.
> @@ -165,6 +166,7 @@ static void ceph_dirty_pages(struct ceph_databuf *dbuf)
> if (bvec[i].bv_page)
> set_page_dirty_lock(bvec[i].bv_page);
> }
> +#endif // TODO: Remove after netfs conversion
>
> /*
> * Prepare an open request. Preallocate ceph_cap to avoid an
> @@ -1021,6 +1023,7 @@ int ceph_release(struct inode *inode, struct file *file)
> return 0;
> }
>
> +#if 0 // TODO: Remove after netfs conversion
> enum {
> HAVE_RETRIED = 1,
> CHECK_EOF = 2,
> @@ -2234,6 +2237,7 @@ static ssize_t ceph_read_iter(struct kiocb *iocb, struct iov_iter *to)
>
> return ret;
> }
> +#endif // TODO: Remove after netfs conversion
>
> /*
> * Wrap filemap_splice_read with checks for cap bits on the inode.
> @@ -2294,6 +2298,7 @@ static ssize_t ceph_splice_read(struct file *in, loff_t *ppos,
> return ret;
> }
>
> +#if 0 // TODO: Remove after netfs conversion
> /*
> * Take cap references to avoid releasing caps to MDS mid-write.
> *
> @@ -2488,6 +2493,7 @@ static ssize_t ceph_write_iter(struct kiocb *iocb, struct iov_iter *from)
> ceph_free_cap_flush(prealloc_cf);
> return written ? written : err;
> }
> +#endif // TODO: Remove after netfs conversion
>
> /*
> * llseek. be sure to verify file size on SEEK_END.
> @@ -3160,6 +3166,10 @@ static int ceph_fadvise(struct file *file, loff_t offset, loff_t len, int advice
> if (fi->fmode & CEPH_FILE_MODE_LAZY)
> return -EACCES;
>
> + ret = netfs_start_io_read(inode);
> + if (ret < 0)
> + return ret;
> +
> ret = ceph_get_caps(file, CEPH_CAP_FILE_RD, want, -1, &got);
> if (ret < 0) {
> doutc(cl, "%llx.%llx, error getting cap\n", ceph_vinop(inode));
> @@ -3180,6 +3190,7 @@ static int ceph_fadvise(struct file *file, loff_t offset, loff_t len, int advice
> inode, ceph_vinop(inode), ceph_cap_string(got), ret);
> ceph_put_cap_refs(ceph_inode(inode), got);
> out:
> + netfs_end_io_read(inode);
> return ret;
> }
>
> @@ -3187,8 +3198,8 @@ const struct file_operations ceph_file_fops = {
> .open = ceph_open,
> .release = ceph_release,
> .llseek = ceph_llseek,
> - .read_iter = ceph_read_iter,
> - .write_iter = ceph_write_iter,
> + .read_iter = ceph_netfs_read_iter,
> + .write_iter = ceph_netfs_write_iter,
> .mmap = ceph_mmap,
> .fsync = ceph_fsync,
> .lock = ceph_lock,
> diff --git a/fs/ceph/inode.c b/fs/ceph/inode.c
> index ec9b80fec7be..8f73f3a55a3e 100644
> --- a/fs/ceph/inode.c
> +++ b/fs/ceph/inode.c
> @@ -2345,11 +2345,9 @@ static int fill_fscrypt_truncate(struct inode *inode,
> struct iov_iter iter;
> struct ceph_fscrypt_truncate_size_header *header;
> void *p;
> - int retry_op = 0;
> int len = CEPH_FSCRYPT_BLOCK_SIZE;
> loff_t i_size = i_size_read(inode);
> int got, ret, issued;
> - u64 objver;
>
> ret = __ceph_get_caps(inode, NULL, CEPH_CAP_FILE_RD, 0, -1, &got);
> if (ret < 0)
> @@ -2361,16 +2359,6 @@ static int fill_fscrypt_truncate(struct inode *inode,
> i_size, attr->ia_size, ceph_cap_string(got),
> ceph_cap_string(issued));
>
> - /* Try to writeback the dirty pagecaches */
> - if (issued & (CEPH_CAP_FILE_BUFFER)) {
> - loff_t lend = orig_pos + CEPH_FSCRYPT_BLOCK_SIZE - 1;
> -
> - ret = filemap_write_and_wait_range(inode->i_mapping,
> - orig_pos, lend);
> - if (ret < 0)
> - goto out;
> - }
> -
> ret = -ENOMEM;
> dbuf = ceph_databuf_req_alloc(2, 0, GFP_KERNEL);
> if (!dbuf)
> @@ -2382,10 +2370,8 @@ static int fill_fscrypt_truncate(struct inode *inode,
> goto out;
>
> iov_iter_bvec(&iter, ITER_DEST, &dbuf->bvec[1], 1, len);
> -
> - pos = orig_pos;
> - ret = __ceph_sync_read(inode, &pos, &iter, &retry_op, &objver);
> - if (ret < 0)
> + ret = netfs_unbuffered_read_from_inode(inode, orig_pos, &iter, true);
> + if (ret < 0 && ret != -ENODATA)
> goto out;
>
> header = kmap_ceph_databuf_page(dbuf, 0);
> @@ -2402,16 +2388,14 @@ static int fill_fscrypt_truncate(struct inode *inode,
> header->block_size = cpu_to_le32(CEPH_FSCRYPT_BLOCK_SIZE);
>
> /*
> - * If we hit a hole here, we should just skip filling
> - * the fscrypt for the request, because once the fscrypt
> - * is enabled, the file will be split into many blocks
> - * with the size of CEPH_FSCRYPT_BLOCK_SIZE, if there
> - * has a hole, the hole size should be multiple of block
> - * size.
> + * If we hit a hole here, we should just skip filling the fscrypt for
> + * the request, because once the fscrypt is enabled, the file will be
> + * split into many blocks with the size of CEPH_FSCRYPT_BLOCK_SIZE. If
> + * there was a hole, the hole size should be multiple of block size.
> *
> * If the Rados object doesn't exist, it will be set to 0.
> */
> - if (!objver) {
> + if (ret != -ENODATA) {
> doutc(cl, "hit hole, ppos %lld < size %lld\n", pos, i_size);
>
> header->data_len = cpu_to_le32(8 + 8 + 4);
> diff --git a/fs/ceph/rdwr.c b/fs/ceph/rdwr.c
> new file mode 100644
> index 000000000000..952c36be2cd9
> --- /dev/null
> +++ b/fs/ceph/rdwr.c
> @@ -0,0 +1,1006 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/* Ceph netfs-based file read-write operations.
> + *
> + * There are a few funny things going on here.
> + *
> + * The page->private field is used to reference a struct ceph_snap_context for
> + * _every_ dirty page. This indicates which snapshot the page was logically
> + * dirtied in, and thus which snap context needs to be associated with the osd
> + * write during writeback.
> + *
> + * Similarly, struct ceph_inode_info maintains a set of counters to count dirty
> + * pages on the inode. In the absence of snapshots, i_wrbuffer_ref ==
> + * i_wrbuffer_ref_head == the dirty page count.
> + *
> + * When a snapshot is taken (that is, when the client receives notification
> + * that a snapshot was taken), each inode with caps and with dirty pages (dirty
> + * pages implies there is a cap) gets a new ceph_cap_snap in the i_cap_snaps
> + * list (which is sorted in ascending order, new snaps go to the tail). The
> + * i_wrbuffer_ref_head count is moved to capsnap->dirty. (Unless a sync write
> + * is currently in progress. In that case, the capsnap is said to be
> + * "pending", new writes cannot start, and the capsnap isn't "finalized" until
> + * the write completes (or fails) and a final size/mtime for the inode for that
> + * snap can be settled upon.) i_wrbuffer_ref_head is reset to 0.
> + *
> + * On writeback, we must submit writes to the osd IN SNAP ORDER. So, we look
> + * for the first capsnap in i_cap_snaps and write out pages in that snap
> + * context _only_. Then we move on to the next capsnap, eventually reaching
> + * the "live" or "head" context (i.e., pages that are not yet snapped) and are
> + * writing the most recently dirtied pages.
> + *
> + * Invalidate and so forth must take care to ensure the dirty page accounting
> + * is preserved.
> + *
> + * Copyright (C) 2025 Red Hat, Inc. All Rights Reserved.
> + * Written by David Howells (dhowells@xxxxxxxxxx)
> + */
> +#include <linux/ceph/ceph_debug.h>
> +
> +#include <linux/backing-dev.h>
> +#include <linux/fs.h>
> +#include <linux/mm.h>
> +#include <linux/swap.h>
> +#include <linux/pagemap.h>
> +#include <linux/slab.h>
> +#include <linux/pagevec.h>
> +#include <linux/task_io_accounting_ops.h>
> +#include <linux/signal.h>
> +#include <linux/iversion.h>
> +#include <linux/ktime.h>
> +#include <linux/netfs.h>
> +#include <trace/events/netfs.h>
> +
> +#include "super.h"
> +#include "mds_client.h"
> +#include "cache.h"
> +#include "metric.h"
> +#include "crypto.h"
> +#include <linux/ceph/osd_client.h>
> +#include <linux/ceph/striper.h>
> +
> +struct ceph_writeback_ctl
> +{
> + loff_t i_size;
> + u64 truncate_size;
> + u32 truncate_seq;
> + bool size_stable;
> + bool head_snapc;
> +};
> +
> +struct kmem_cache *ceph_io_request_cachep;
> +struct kmem_cache *ceph_io_subrequest_cachep;
> +
> +static struct ceph_io_subrequest *ceph_sreq2io(struct netfs_io_subrequest *subreq)
> +{
> + BUILD_BUG_ON(sizeof(struct ceph_io_request) > NETFS_DEF_IO_REQUEST_SIZE);
> + BUILD_BUG_ON(sizeof(struct ceph_io_subrequest) > NETFS_DEF_IO_SUBREQUEST_SIZE);
> +
> + return container_of(subreq, struct ceph_io_subrequest, sreq);
> +}
> +
> +/*
> + * Get the snapc from the group attached to a request
> + */
> +static struct ceph_snap_context *ceph_wreq_snapc(struct netfs_io_request *wreq)
> +{
> + struct ceph_snap_context *snapc =
> + container_of(wreq->group, struct ceph_snap_context, group);
> + return snapc;
> +}
> +
> +#if 0
> +static void ceph_put_many_snap_context(struct ceph_snap_context *sc, unsigned int nr)
> +{
> + if (sc)
> + netfs_put_group_many(&sc->group, nr);
> +}
> +#endif
> +
> +/*
> + * Handle the termination of a write to the server.
> + */
> +static void ceph_netfs_write_callback(struct ceph_osd_request *req)
> +{
> + struct netfs_io_subrequest *subreq = req->r_subreq;
> + struct ceph_io_subrequest *csub = ceph_sreq2io(subreq);
> + struct ceph_io_request *creq = csub->creq;
> + struct inode *inode = creq->rreq.inode;
> + struct ceph_inode_info *ci = ceph_inode(inode);
> + struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
> + struct ceph_client *cl = ceph_inode_to_client(inode);
> + size_t wrote = req->r_result ? 0 : subreq->len;
> + int err = req->r_result;
> +
> + trace_netfs_sreq(subreq, netfs_sreq_trace_io_progress);
> +
> + ceph_update_write_metrics(&fsc->mdsc->metric, req->r_start_latency,
> + req->r_end_latency, wrote, err);
> +
> + if (err) {
> + doutc(cl, "sync_write osd write returned %d\n", err);
> + /* Version changed! Must re-do the rmw cycle */
> + if ((creq->rmw_assert_version && (err == -ERANGE || err == -EOVERFLOW)) ||
> + (!creq->rmw_assert_version && err == -EEXIST)) {
> + /* We should only ever see this on a rmw */
> + WARN_ON_ONCE(!test_bit(NETFS_RREQ_RMW, &ci->netfs.flags));
> +
> + /* The version should never go backward */
> + WARN_ON_ONCE(err == -EOVERFLOW);
> +
> + /* FIXME: limit number of times we loop? */
> + set_bit(NETFS_RREQ_REPEAT_RMW, &creq->rreq.flags);
> + trace_netfs_sreq(subreq, netfs_sreq_trace_need_rmw);
> + }
> + ceph_set_error_write(ci);
> + } else {
> + ceph_clear_error_write(ci);
> + }
> +
> + csub->req = NULL;
> + ceph_osdc_put_request(req);
> + netfs_write_subrequest_terminated(subreq, err ?: wrote, true);
> +}
> +
> +/*
> + * Issue a subrequest to upload to the server.
> + */
> +static void ceph_issue_write(struct netfs_io_subrequest *subreq)
> +{
> + struct ceph_io_subrequest *csub = ceph_sreq2io(subreq);
> + struct ceph_snap_context *snapc = ceph_wreq_snapc(subreq->rreq);
> + struct ceph_osd_request *req;
> + struct ceph_io_request *creq = csub->creq;
> + struct ceph_fs_client *fsc = ceph_inode_to_fs_client(subreq->rreq->inode);
> + struct ceph_osd_client *osdc = &fsc->client->osdc;
> + struct inode *inode = subreq->rreq->inode;
> + struct ceph_inode_info *ci = ceph_inode(inode);
> + struct ceph_client *cl = ceph_inode_to_client(inode);
> + unsigned long long len;
> + unsigned int rmw = test_bit(NETFS_RREQ_RMW, &ci->netfs.flags) ? 1 : 0;
> +
> + doutc(cl, "issue_write R=%08x[%x] ino %llx %lld~%zu -- %srmw\n",
> + subreq->rreq->debug_id, subreq->debug_index, ci->i_vino.ino,
> + subreq->start, subreq->len,
> + rmw ? "" : "no ");
> +
> + len = subreq->len;
> + req = ceph_osdc_new_request(osdc, &ci->i_layout, ci->i_vino,
> + subreq->start, &len,
> + rmw, /* which: 0 or 1 */
> + rmw + 1, /* num_ops: 1 or 2 */
> + CEPH_OSD_OP_WRITE,
> + CEPH_OSD_FLAG_WRITE,
> + snapc,
> + ci->i_truncate_seq,
> + ci->i_truncate_size, false);
> + if (IS_ERR(req)) {
> + netfs_write_subrequest_terminated(subreq, PTR_ERR(req), false);
> + return netfs_prepare_write_failed(subreq);
> + }
> +
> + subreq->len = len;
> + doutc(cl, "write op %lld~%zu\n", subreq->start, subreq->len);
> + iov_iter_truncate(&subreq->io_iter, len);
> + osd_req_op_extent_osd_iter(req, 0, &subreq->io_iter);
> + req->r_inode = inode;
> + req->r_mtime = current_time(inode);
> + req->r_callback = ceph_netfs_write_callback;
> + req->r_subreq = subreq;
> + csub->req = req;
> +
> + /*
> + * If we're doing an RMW cycle, set up an assertion that the remote
> + * data hasn't changed. If we don't have a version number, then the
> + * object doesn't exist yet. Use an exclusive create instead of a
> + * version assertion in that case.
> + */
> + if (rmw) {
> + if (creq->rmw_assert_version) {
> + osd_req_op_init(req, 0, CEPH_OSD_OP_ASSERT_VER, 0);
> + req->r_ops[0].assert_ver.ver = creq->rmw_assert_version;
> + } else {
> + osd_req_op_init(req, 0, CEPH_OSD_OP_CREATE,
> + CEPH_OSD_OP_FLAG_EXCL);
> + }
> + }
> +
> + trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
> + ceph_osdc_start_request(osdc, req);
> +}
> +
> +/*
> + * Prepare a subrequest to upload to the server.
> + */
> +static void ceph_prepare_write(struct netfs_io_subrequest *subreq)
> +{
> + struct ceph_inode_info *ci = ceph_inode(subreq->rreq->inode);
> + struct ceph_fs_client *fsc = ceph_inode_to_fs_client(subreq->rreq->inode);
> + u64 objnum, objoff;
> +
> + /* Clamp the length to the next object boundary. */
> + ceph_calc_file_object_mapping(&ci->i_layout, subreq->start,
> + fsc->mount_options->wsize,
> + &objnum, &objoff,
> + &subreq->rreq->io_streams[0].sreq_max_len);
> +}
> +
> +/*
> + * Mark the caps as dirty
> + */
> +static void ceph_netfs_post_modify(struct inode *inode, void *fs_priv)
> +{
> + struct ceph_inode_info *ci = ceph_inode(inode);
> + struct ceph_cap_flush **prealloc_cf = fs_priv;
> + int dirty;
> +
> + spin_lock(&ci->i_ceph_lock);
> + dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR, prealloc_cf);
> + spin_unlock(&ci->i_ceph_lock);
> + if (dirty)
> + __mark_inode_dirty(inode, dirty);
> +}
> +
> +static void ceph_netfs_expand_readahead(struct netfs_io_request *rreq)
> +{
> + struct inode *inode = rreq->inode;
> + struct ceph_inode_info *ci = ceph_inode(inode);
> + struct ceph_file_layout *lo = &ci->i_layout;
> + unsigned long max_pages = inode->i_sb->s_bdi->ra_pages;
> + loff_t end = rreq->start + rreq->len, new_end;
> + struct ceph_io_request *priv = container_of(rreq, struct ceph_io_request, rreq);
> + unsigned long max_len;
> + u32 blockoff;
> +
> + if (priv) {
> + /* Readahead is disabled by posix_fadvise POSIX_FADV_RANDOM */
> + if (priv->file_ra_disabled)
> + max_pages = 0;
> + else
> + max_pages = priv->file_ra_pages;
> +
> + }
> +
> + /* Readahead is disabled */
> + if (!max_pages)
> + return;
> +
> + max_len = max_pages << PAGE_SHIFT;
> +
> + /*
> + * Try to expand the length forward by rounding up it to the next
> + * block, but do not exceed the file size, unless the original
> + * request already exceeds it.
> + */
> + new_end = umin(round_up(end, lo->stripe_unit), rreq->i_size);
> + if (new_end > end && new_end <= rreq->start + max_len)
> + rreq->len = new_end - rreq->start;
> +
> + /* Try to expand the start downward */
> + div_u64_rem(rreq->start, lo->stripe_unit, &blockoff);
> + if (rreq->len + blockoff <= max_len) {
> + rreq->start -= blockoff;
> + rreq->len += blockoff;
> + }
> +}
> +
> +static int ceph_netfs_prepare_read(struct netfs_io_subrequest *subreq)
> +{
> + struct netfs_io_request *rreq = subreq->rreq;
> + struct ceph_inode_info *ci = ceph_inode(rreq->inode);
> + struct ceph_fs_client *fsc = ceph_inode_to_fs_client(rreq->inode);
> + size_t xlen;
> + u64 objno, objoff;
> +
> + /* Truncate the extent at the end of the current block */
> + ceph_calc_file_object_mapping(&ci->i_layout, subreq->start, subreq->len,
> + &objno, &objoff, &xlen);
> + rreq->io_streams[0].sreq_max_len = umin(xlen, fsc->mount_options->rsize);
> + return 0;
> +}
> +
> +static void ceph_netfs_read_callback(struct ceph_osd_request *req)
> +{
> + struct inode *inode = req->r_inode;
> + struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
> + struct ceph_client *cl = fsc->client;
> + struct ceph_osd_data *osd_data = osd_req_op_extent_osd_data(req, 0);
> + struct netfs_io_subrequest *subreq = req->r_priv;
> + struct ceph_osd_req_op *op = &req->r_ops[0];
> + bool sparse = (op->op == CEPH_OSD_OP_SPARSE_READ);
> + int err = req->r_result;
> +
> + ceph_update_read_metrics(&fsc->mdsc->metric, req->r_start_latency,
> + req->r_end_latency, osd_data->iter.count, err);
> +
> + doutc(cl, "result %d subreq->len=%zu i_size=%lld\n", req->r_result,
> + subreq->len, i_size_read(req->r_inode));
> +
> + /* no object means success but no data */
> + if (err == -ENOENT)
> + err = 0;
> + else if (err == -EBLOCKLISTED)
> + fsc->blocklisted = true;
> +
> + if (err >= 0) {

Maybe, we need not to use err here. It looks really confusing for the case of
positive value. I assume that positive value of req->r_result is not error code.

> + if (sparse && err > 0)
> + err = ceph_sparse_ext_map_end(op);
> + if (err < subreq->len &&
> + subreq->rreq->origin != NETFS_DIO_READ)
> + __set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
> + if (IS_ENCRYPTED(inode) && err > 0) {
> +#if 0
> + err = ceph_fscrypt_decrypt_extents(inode, osd_data->dbuf,
> + subreq->start,
> + op->extent.sparse_ext,
> + op->extent.sparse_ext_cnt);
> + if (err > subreq->len)
> + err = subreq->len;
> +#else
> + pr_err("TODO: Content-decrypt currently disabled\n");
> + err = -EOPNOTSUPP;
> +#endif
> + }
> + }
> +
> + if (err > 0) {
> + subreq->transferred = err;
> + err = 0;
> + }
> +
> + subreq->error = err;

So, err is error code or not? :)

> + trace_netfs_sreq(subreq, netfs_sreq_trace_io_progress);
> + ceph_dec_osd_stopping_blocker(fsc->mdsc);
> + netfs_read_subreq_terminated(subreq);
> +}
> +
> +static void ceph_rmw_read_done(struct netfs_io_request *wreq, struct netfs_io_request *rreq)
> +{
> + struct ceph_io_request *cwreq = container_of(wreq, struct ceph_io_request, rreq);
> + struct ceph_io_request *crreq = container_of(rreq, struct ceph_io_request, rreq);
> +
> + cwreq->rmw_assert_version = crreq->rmw_assert_version;
> +}
> +
> +static bool ceph_netfs_issue_read_inline(struct netfs_io_subrequest *subreq)
> +{
> + struct netfs_io_request *rreq = subreq->rreq;
> + struct inode *inode = rreq->inode;
> + struct ceph_mds_reply_info_parsed *rinfo;
> + struct ceph_mds_reply_info_in *iinfo;
> + struct ceph_mds_request *req;
> + struct ceph_mds_client *mdsc = ceph_sb_to_mdsc(inode->i_sb);
> + struct ceph_inode_info *ci = ceph_inode(inode);
> + ssize_t err = 0;
> + size_t len, copied;
> + int mode;
> +
> + __clear_bit(NETFS_SREQ_COPY_TO_CACHE, &subreq->flags);
> +
> + if (subreq->start >= inode->i_size)

Maybe, i_size_read(inode)?

> + goto out;
> +
> + /* We need to fetch the inline data. */
> + mode = ceph_try_to_choose_auth_mds(inode, CEPH_STAT_CAP_INLINE_DATA);
> + req = ceph_mdsc_create_request(mdsc, CEPH_MDS_OP_GETATTR, mode);
> + if (IS_ERR(req)) {
> + err = PTR_ERR(req);
> + goto out;
> + }
> + req->r_ino1 = ci->i_vino;
> + req->r_args.getattr.mask = cpu_to_le32(CEPH_STAT_CAP_INLINE_DATA);
> + req->r_num_caps = 2;
> +
> + trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
> + err = ceph_mdsc_do_request(mdsc, NULL, req);
> + if (err < 0)
> + goto out;
> +
> + rinfo = &req->r_reply_info;
> + iinfo = &rinfo->targeti;
> + if (iinfo->inline_version == CEPH_INLINE_NONE) {
> + /* The data got uninlined */
> + ceph_mdsc_put_request(req);
> + return false;
> + }
> +
> + len = umin(iinfo->inline_len - subreq->start, subreq->len);
> + copied = copy_to_iter(iinfo->inline_data + subreq->start, len, &subreq->io_iter);
> + if (copied) {
> + subreq->transferred += copied;
> + if (copied == len)
> + __set_bit(NETFS_SREQ_HIT_EOF, &subreq->flags);
> + subreq->error = 0;
> + } else {
> + subreq->error = -EFAULT;
> + }
> +
> + ceph_mdsc_put_request(req);
> +out:
> + netfs_read_subreq_terminated(subreq);
> + return true;
> +}
> +
> +static void ceph_netfs_issue_read(struct netfs_io_subrequest *subreq)
> +{
> + struct netfs_io_request *rreq = subreq->rreq;
> + struct inode *inode = rreq->inode;
> + struct ceph_inode_info *ci = ceph_inode(inode);
> + struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
> + struct ceph_client *cl = fsc->client;
> + struct ceph_osd_request *req = NULL;
> + struct ceph_vino vino = ceph_vino(inode);
> + int extent_cnt;
> + bool sparse = IS_ENCRYPTED(inode) || ceph_test_mount_opt(fsc, SPARSEREAD);
> + u64 off = subreq->start, len = subreq->len;
> + int err = 0;
> +
> + if (ceph_inode_is_shutdown(inode)) {
> + err = -EIO;
> + goto out;
> + }
> +
> + if (ceph_has_inline_data(ci) && ceph_netfs_issue_read_inline(subreq))
> + return;
> +
> + req = ceph_osdc_new_request(&fsc->client->osdc, &ci->i_layout, vino,
> + off, &len, 0, 1,
> + sparse ? CEPH_OSD_OP_SPARSE_READ : CEPH_OSD_OP_READ,
> + CEPH_OSD_FLAG_READ, /* read_from_replica will be or'd in */
> + NULL, ci->i_truncate_seq, ci->i_truncate_size, false);
> + if (IS_ERR(req)) {
> + err = PTR_ERR(req);
> + req = NULL;
> + goto out;
> + }
> +
> + if (sparse) {
> + extent_cnt = __ceph_sparse_read_ext_count(inode, len);
> + err = ceph_alloc_sparse_ext_map(&req->r_ops[0], extent_cnt);
> + if (err)
> + goto out;
> + }
> +
> + doutc(cl, "%llx.%llx pos=%llu orig_len=%zu len=%llu\n",
> + ceph_vinop(inode), subreq->start, subreq->len, len);
> +
> + osd_req_op_extent_osd_iter(req, 0, &subreq->io_iter);
> + if (!ceph_inc_osd_stopping_blocker(fsc->mdsc)) {
> + err = -EIO;
> + goto out;
> + }
> + req->r_callback = ceph_netfs_read_callback;
> + req->r_priv = subreq;
> + req->r_inode = inode;
> +
> + trace_netfs_sreq(subreq, netfs_sreq_trace_submit);
> + ceph_osdc_start_request(req->r_osdc, req);
> +out:
> + ceph_osdc_put_request(req);
> + doutc(cl, "%llx.%llx result %d\n", ceph_vinop(inode), err);
> + if (err) {
> + subreq->error = err;
> + netfs_read_subreq_terminated(subreq);
> + }
> +}
> +
> +static int ceph_init_request(struct netfs_io_request *rreq, struct file *file)
> +{
> + struct ceph_io_request *priv = container_of(rreq, struct ceph_io_request, rreq);
> + struct inode *inode = rreq->inode;
> + struct ceph_client *cl = ceph_inode_to_client(inode);
> + struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
> + int got = 0, want = CEPH_CAP_FILE_CACHE;
> + int ret = 0;
> +
> + rreq->rsize = 1024 * 1024;

Why do we hardcoded rreq->rsize value?

struct ceph_mount_options {
unsigned int flags;

unsigned int wsize; /* max write size */
unsigned int rsize; /* max read size */
unsigned int rasize; /* max readahead */
unsigned int congestion_kb; /* max writeback in flight */
unsigned int caps_wanted_delay_min, caps_wanted_delay_max;
int caps_max;
unsigned int max_readdir; /* max readdir result (entries) */
unsigned int max_readdir_bytes; /* max readdir result (bytes) */

bool new_dev_syntax;

/*
* everything above this point can be memcmp'd; everything below
* is handled in compare_mount_options()
*/

char *snapdir_name; /* default ".snap" */
char *mds_namespace; /* default NULL */
char *server_path; /* default NULL (means "/") */
char *fscache_uniq; /* default NULL */
char *mon_addr;
struct fscrypt_dummy_policy dummy_enc_policy;
};

Why we don't use fsc->mount_options->rsize?

> + rreq->wsize = umin(i_blocksize(inode), fsc->mount_options->wsize);
> +
> + switch (rreq->origin) {
> + case NETFS_READAHEAD:
> + goto init_readahead;
> + case NETFS_WRITEBACK:
> + case NETFS_WRITETHROUGH:
> + case NETFS_UNBUFFERED_WRITE:
> + case NETFS_DIO_WRITE:
> + if (S_ISREG(rreq->inode->i_mode))
> + rreq->io_streams[0].avail = true;
> + return 0;
> + default:
> + return 0;
> + }
> +
> +init_readahead:
> + /*
> + * If we are doing readahead triggered by a read, fault-in or
> + * MADV/FADV_WILLNEED, someone higher up the stack must be holding the
> + * FILE_CACHE and/or LAZYIO caps.
> + */
> + if (file) {
> + priv->file_ra_pages = file->f_ra.ra_pages;
> + priv->file_ra_disabled = file->f_mode & FMODE_RANDOM;
> + rreq->netfs_priv = priv;
> + return 0;
> + }
> +
> + /*
> + * readahead callers do not necessarily hold Fcb caps
> + * (e.g. fadvise, madvise).
> + */
> + ret = ceph_try_get_caps(inode, CEPH_CAP_FILE_RD, want, true, &got);
> + if (ret < 0) {
> + doutc(cl, "%llx.%llx, error getting cap\n", ceph_vinop(inode));
> + goto out;
> + }
> +
> + if (!(got & want)) {
> + doutc(cl, "%llx.%llx, no cache cap\n", ceph_vinop(inode));
> + ret = -EACCES;
> + goto out;
> + }
> + if (ret > 0)
> + priv->caps = got;
> + else
> + ret = -EACCES;
> +
> + rreq->io_streams[0].sreq_max_len = fsc->mount_options->rsize;
> +out:
> + return ret;
> +}
> +
> +static void ceph_netfs_free_request(struct netfs_io_request *rreq)
> +{
> + struct ceph_io_request *creq = container_of(rreq, struct ceph_io_request, rreq);
> +
> + if (creq->caps)
> + ceph_put_cap_refs(ceph_inode(rreq->inode), creq->caps);
> +}
> +
> +const struct netfs_request_ops ceph_netfs_ops = {
> + .init_request = ceph_init_request,
> + .free_request = ceph_netfs_free_request,
> + .expand_readahead = ceph_netfs_expand_readahead,
> + .prepare_read = ceph_netfs_prepare_read,
> + .issue_read = ceph_netfs_issue_read,
> + .rmw_read_done = ceph_rmw_read_done,
> + .post_modify = ceph_netfs_post_modify,
> + .prepare_write = ceph_prepare_write,
> + .issue_write = ceph_issue_write,
> +};
> +
> +/*
> + * Get ref for the oldest snapc for an inode with dirty data... that is, the
> + * only snap context we are allowed to write back.
> + */
> +static struct ceph_snap_context *
> +ceph_get_oldest_context(struct inode *inode, struct ceph_writeback_ctl *ctl,
> + struct ceph_snap_context *folio_snapc)
> +{
> + struct ceph_snap_context *snapc = NULL;
> + struct ceph_inode_info *ci = ceph_inode(inode);
> + struct ceph_cap_snap *capsnap = NULL;
> + struct ceph_client *cl = ceph_inode_to_client(inode);
> +
> + spin_lock(&ci->i_ceph_lock);
> + list_for_each_entry(capsnap, &ci->i_cap_snaps, ci_item) {
> + doutc(cl, " capsnap %p snapc %p has %d dirty pages\n",
> + capsnap, capsnap->context, capsnap->dirty_pages);
> + if (!capsnap->dirty_pages)
> + continue;
> +
> + /* get i_size, truncate_{seq,size} for folio_snapc? */
> + if (snapc && capsnap->context != folio_snapc)
> + continue;
> +
> + if (ctl) {
> + if (capsnap->writing) {
> + ctl->i_size = i_size_read(inode);
> + ctl->size_stable = false;
> + } else {
> + ctl->i_size = capsnap->size;
> + ctl->size_stable = true;
> + }
> + ctl->truncate_size = capsnap->truncate_size;
> + ctl->truncate_seq = capsnap->truncate_seq;
> + ctl->head_snapc = false;
> + }
> +
> + if (snapc)
> + break;
> +
> + snapc = ceph_get_snap_context(capsnap->context);
> + if (!folio_snapc ||
> + folio_snapc == snapc ||
> + folio_snapc->seq > snapc->seq)
> + break;
> + }
> + if (!snapc && ci->i_wrbuffer_ref_head) {
> + snapc = ceph_get_snap_context(ci->i_head_snapc);
> + doutc(cl, " head snapc %p has %d dirty pages\n", snapc,
> + ci->i_wrbuffer_ref_head);
> + if (ctl) {
> + ctl->i_size = i_size_read(inode);
> + ctl->truncate_size = ci->i_truncate_size;
> + ctl->truncate_seq = ci->i_truncate_seq;
> + ctl->size_stable = false;
> + ctl->head_snapc = true;
> + }
> + }
> + spin_unlock(&ci->i_ceph_lock);
> + return snapc;
> +}
> +
> +/*
> + * Flush dirty data. We have to start with the oldest snap as that's the only
> + * one we're allowed to write back.
> + */
> +static int ceph_writepages(struct address_space *mapping,
> + struct writeback_control *wbc)
> +{
> + struct ceph_writeback_ctl ceph_wbc;
> + struct ceph_snap_context *snapc;
> + struct ceph_inode_info *ci = ceph_inode(mapping->host);
> + loff_t actual_start = wbc->range_start, actual_end = wbc->range_end;
> + int ret;
> +
> + do {
> + snapc = ceph_get_oldest_context(mapping->host, &ceph_wbc, NULL);
> + if (snapc == ci->i_head_snapc) {
> + wbc->range_start = actual_start;
> + wbc->range_end = actual_end;
> + } else {
> + /* Do not respect wbc->range_{start,end}. Dirty pages
> + * in that range can be associated with newer snapc.
> + * They are not writeable until we write all dirty
> + * pages associated with an older snapc get written.
> + */
> + wbc->range_start = 0;
> + wbc->range_end = LLONG_MAX;
> + }
> +
> + ret = netfs_writepages_group(mapping, wbc, &snapc->group, &ceph_wbc);
> + ceph_put_snap_context(snapc);
> + if (snapc == ci->i_head_snapc)
> + break;
> + } while (ret == 0 && wbc->nr_to_write > 0);
> +
> + return ret;
> +}
> +
> +const struct address_space_operations ceph_aops = {
> + .read_folio = netfs_read_folio,
> + .readahead = netfs_readahead,
> + .writepages = ceph_writepages,
> + .dirty_folio = ceph_dirty_folio,
> + .invalidate_folio = netfs_invalidate_folio,
> + .release_folio = netfs_release_folio,
> + .direct_IO = noop_direct_IO,
> + .migrate_folio = filemap_migrate_folio,
> +};
> +
> +/*
> + * Wrap generic_file_aio_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.
> + *
> + * Hmm, the sync read case isn't actually async... should it be?
> + */
> +ssize_t ceph_netfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
> +{
> + struct file *filp = iocb->ki_filp;
> + struct inode *inode = file_inode(filp);
> + struct ceph_inode_info *ci = ceph_inode(inode);
> + struct ceph_file_info *fi = filp->private_data;
> + struct ceph_client *cl = ceph_inode_to_client(inode);
> + ssize_t ret;
> + size_t len = iov_iter_count(to);
> + bool dio = iocb->ki_flags & IOCB_DIRECT;
> + int want = 0, got = 0;
> +
> + doutc(cl, "%llu~%zu trying to get caps on %p %llx.%llx\n",
> + iocb->ki_pos, len, inode, ceph_vinop(inode));
> +
> + if (ceph_inode_is_shutdown(inode))
> + return -ESTALE;
> +
> + if (dio)
> + ret = netfs_start_io_direct(inode);
> + else
> + ret = netfs_start_io_read(inode);
> + if (ret < 0)
> + return ret;
> +
> + if (!(fi->flags & CEPH_F_SYNC) && !dio)
> + want |= CEPH_CAP_FILE_CACHE;
> + if (fi->fmode & CEPH_FILE_MODE_LAZY)
> + want |= CEPH_CAP_FILE_LAZYIO;
> +
> + ret = ceph_get_caps(filp, CEPH_CAP_FILE_RD, want, -1, &got);
> + if (ret < 0)
> + goto out;
> +
> + if ((got & (CEPH_CAP_FILE_CACHE|CEPH_CAP_FILE_LAZYIO)) == 0 ||
> + dio ||
> + (fi->flags & CEPH_F_SYNC)) {
> + doutc(cl, "sync %p %llx.%llx %llu~%zu got cap refs on %s\n",
> + inode, ceph_vinop(inode), iocb->ki_pos, len,
> + ceph_cap_string(got));
> +
> + ret = netfs_unbuffered_read_iter(iocb, to);
> + } else {
> + doutc(cl, "async %p %llx.%llx %llu~%zu got cap refs on %s\n",
> + inode, ceph_vinop(inode), iocb->ki_pos, len,
> + ceph_cap_string(got));
> + ret = filemap_read(iocb, to, 0);
> + }
> +
> + doutc(cl, "%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:
> + if (dio)
> + netfs_end_io_direct(inode);
> + else
> + netfs_end_io_read(inode);
> + return ret;
> +}
> +
> +/*
> + * Get the most recent snap context in the list to which the inode subscribes.
> + * This is the only one we are allowed to modify. If a folio points to an
> + * earlier snapshot, it must be flushed first.
> + */
> +static struct ceph_snap_context *ceph_get_most_recent_snapc(struct inode *inode)
> +{
> + struct ceph_snap_context *snapc;
> + struct ceph_inode_info *ci = ceph_inode(inode);
> +
> + /* Get the snap this write is going to belong to. */
> + spin_lock(&ci->i_ceph_lock);
> + if (__ceph_have_pending_cap_snap(ci)) {
> + struct ceph_cap_snap *capsnap =
> + list_last_entry(&ci->i_cap_snaps,
> + struct ceph_cap_snap, ci_item);
> +
> + snapc = ceph_get_snap_context(capsnap->context);
> + } else {
> + BUG_ON(!ci->i_head_snapc);
> + snapc = ceph_get_snap_context(ci->i_head_snapc);
> + }
> + spin_unlock(&ci->i_ceph_lock);
> +
> + return snapc;
> +}
> +
> +/*
> + * Take cap references to avoid releasing caps to MDS mid-write.
> + *
> + * If we are synchronous, and write with an old snap context, the OSD
> + * may return EOLDSNAPC. In that case, retry the write.. _after_
> + * dropping our cap refs and allowing the pending snap to logically
> + * complete _before_ this write occurs.
> + *
> + * If we are near ENOSPC, write synchronously.
> + */
> +ssize_t ceph_netfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
> +{
> + struct file *file = iocb->ki_filp;
> + struct inode *inode = file_inode(file);
> + struct ceph_snap_context *snapc;
> + struct ceph_inode_info *ci = ceph_inode(inode);
> + struct ceph_fs_client *fsc = ceph_inode_to_fs_client(inode);
> + struct ceph_file_info *fi = file->private_data;
> + struct ceph_osd_client *osdc = &fsc->client->osdc;
> + struct ceph_cap_flush *prealloc_cf;
> + struct ceph_client *cl = fsc->client;
> + ssize_t count, written = 0;
> + loff_t limit = max(i_size_read(inode), fsc->max_file_size);

Do we need to take into account the quota max bytes here?

struct ceph_inode_info {
<skipped>

/* quotas */
u64 i_max_bytes, i_max_files;

<skipped>
};

> + loff_t pos;
> + bool direct_lock = false;
> + u64 pool_flags;
> + u32 map_flags;
> + int err, want = 0, got;
> +
> + if (ceph_inode_is_shutdown(inode))
> + return -ESTALE;
> +
> + if (ceph_snap(inode) != CEPH_NOSNAP)
> + return -EROFS;
> +
> + prealloc_cf = ceph_alloc_cap_flush();
> + if (!prealloc_cf)
> + return -ENOMEM;
> +
> + if ((iocb->ki_flags & (IOCB_DIRECT | IOCB_APPEND)) == IOCB_DIRECT)
> + direct_lock = true;
> +
> +retry_snap:
> + if (direct_lock)
> + netfs_start_io_direct(inode);
> + else
> + netfs_start_io_write(inode);
> +
> + if (iocb->ki_flags & IOCB_APPEND) {
> + err = ceph_do_getattr(inode, CEPH_STAT_CAP_SIZE, false);
> + if (err < 0)
> + goto out;
> + }
> +
> + err = generic_write_checks(iocb, from);
> + if (err <= 0)
> + goto out;
> +
> + pos = iocb->ki_pos;
> + if (unlikely(pos >= limit)) {
> + err = -EFBIG;
> + goto out;
> + } else {
> + iov_iter_truncate(from, limit - pos);
> + }
> +
> + count = iov_iter_count(from);
> + if (ceph_quota_is_max_bytes_exceeded(inode, pos + count)) {
> + err = -EDQUOT;
> + goto out;
> + }
> +
> + down_read(&osdc->lock);
> + map_flags = osdc->osdmap->flags;
> + pool_flags = ceph_pg_pool_flags(osdc->osdmap, ci->i_layout.pool_id);
> + up_read(&osdc->lock);
> + if ((map_flags & CEPH_OSDMAP_FULL) ||
> + (pool_flags & CEPH_POOL_FLAG_FULL)) {
> + err = -ENOSPC;
> + goto out;
> + }
> +
> + err = file_remove_privs(file);
> + if (err)
> + goto out;
> +
> + doutc(cl, "%p %llx.%llx %llu~%zd getting caps. i_size %llu\n",
> + inode, ceph_vinop(inode), pos, count,
> + i_size_read(inode));
> + if (!(fi->flags & CEPH_F_SYNC) && !direct_lock)
> + want |= CEPH_CAP_FILE_BUFFER;
> + if (fi->fmode & CEPH_FILE_MODE_LAZY)
> + want |= CEPH_CAP_FILE_LAZYIO;
> + got = 0;
> + err = ceph_get_caps(file, CEPH_CAP_FILE_WR, want, pos + count, &got);
> + if (err < 0)
> + goto out;
> +
> + err = file_update_time(file);
> + if (err)
> + goto out_caps;
> +
> + inode_inc_iversion_raw(inode);
> +
> + doutc(cl, "%p %llx.%llx %llu~%zd got cap refs on %s\n",
> + inode, ceph_vinop(inode), pos, count, ceph_cap_string(got));
> +
> + /* Get the snap this write is going to belong to. */
> + snapc = ceph_get_most_recent_snapc(inode);
> +
> + if ((got & (CEPH_CAP_FILE_BUFFER|CEPH_CAP_FILE_LAZYIO)) == 0 ||
> + (iocb->ki_flags & IOCB_DIRECT) || (fi->flags & CEPH_F_SYNC) ||
> + (ci->i_ceph_flags & CEPH_I_ERROR_WRITE)) {
> + struct iov_iter data;
> +
> + /* we might need to revert back to that point */
> + data = *from;
> + written = netfs_unbuffered_write_iter_locked(iocb, &data, &snapc->group);
> + if (direct_lock)
> + netfs_end_io_direct(inode);
> + else
> + netfs_end_io_write(inode);
> + if (written > 0)
> + iov_iter_advance(from, written);
> + ceph_put_snap_context(snapc);
> + } else {
> + /*
> + * No need to acquire the i_truncate_mutex. Because the MDS
> + * revokes Fwb caps before sending truncate message to us. We
> + * can't get Fwb cap while there are pending vmtruncate. So
> + * write and vmtruncate can not run at the same time
> + */
> + written = netfs_perform_write(iocb, from, &snapc->group, &prealloc_cf);
> + netfs_end_io_write(inode);
> + }
> +
> + if (written >= 0) {
> + int dirty;
> +
> + spin_lock(&ci->i_ceph_lock);
> + dirty = __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR,
> + &prealloc_cf);
> + spin_unlock(&ci->i_ceph_lock);
> + if (dirty)
> + __mark_inode_dirty(inode, dirty);
> + if (ceph_quota_is_max_bytes_approaching(inode, iocb->ki_pos))
> + ceph_check_caps(ci, CHECK_CAPS_FLUSH);
> + }
> +
> + doutc(cl, "%p %llx.%llx %llu~%u dropping cap refs on %s\n",
> + inode, ceph_vinop(inode), pos, (unsigned)count,
> + ceph_cap_string(got));
> + ceph_put_cap_refs(ci, got);
> +
> + if (written == -EOLDSNAPC) {
> + doutc(cl, "%p %llx.%llx %llu~%u" "got EOLDSNAPC, retrying\n",
> + inode, ceph_vinop(inode), pos, (unsigned)count);
> + goto retry_snap;
> + }
> +
> + if (written >= 0) {
> + if ((map_flags & CEPH_OSDMAP_NEARFULL) ||
> + (pool_flags & CEPH_POOL_FLAG_NEARFULL))
> + iocb->ki_flags |= IOCB_DSYNC;
> + written = generic_write_sync(iocb, written);
> + }
> +
> + goto out_unlocked;
> +out_caps:
> + ceph_put_cap_refs(ci, got);
> +out:
> + if (direct_lock)
> + netfs_end_io_direct(inode);
> + else
> + netfs_end_io_write(inode);
> +out_unlocked:
> + ceph_free_cap_flush(prealloc_cf);
> + return written ? written : err;
> +}
> +
> +vm_fault_t ceph_page_mkwrite(struct vm_fault *vmf)
> +{
> + struct ceph_snap_context *snapc;
> + struct vm_area_struct *vma = vmf->vma;
> + struct inode *inode = file_inode(vma->vm_file);
> + struct ceph_client *cl = ceph_inode_to_client(inode);
> + struct ceph_inode_info *ci = ceph_inode(inode);
> + struct ceph_file_info *fi = vma->vm_file->private_data;
> + struct ceph_cap_flush *prealloc_cf;
> + struct folio *folio = page_folio(vmf->page);
> + loff_t size = i_size_read(inode);
> + loff_t off = folio_pos(folio);
> + size_t len = folio_size(folio);
> + int want, got, err;
> + vm_fault_t ret = VM_FAULT_SIGBUS;
> +
> + if (ceph_inode_is_shutdown(inode))
> + return ret;
> +
> + prealloc_cf = ceph_alloc_cap_flush();
> + if (!prealloc_cf)
> + return -ENOMEM;
> +
> + doutc(cl, "%llx.%llx %llu~%zd getting caps i_size %llu\n",
> + ceph_vinop(inode), off, len, size);
> + if (fi->fmode & CEPH_FILE_MODE_LAZY)
> + want = CEPH_CAP_FILE_BUFFER | CEPH_CAP_FILE_LAZYIO;
> + else
> + want = CEPH_CAP_FILE_BUFFER;
> +
> + got = 0;
> + err = ceph_get_caps(vma->vm_file, CEPH_CAP_FILE_WR, want, off + len, &got);
> + if (err < 0)
> + goto out_free;
> +
> + doutc(cl, "%llx.%llx %llu~%zd got cap refs on %s\n", ceph_vinop(inode),
> + off, len, ceph_cap_string(got));
> +
> + /* Get the snap this write is going to belong to. */
> + snapc = ceph_get_most_recent_snapc(inode);
> +
> + ret = netfs_page_mkwrite(vmf, &snapc->group, &prealloc_cf);
> +
> + doutc(cl, "%llx.%llx %llu~%zd dropping cap refs on %s ret %x\n",
> + ceph_vinop(inode), off, len, ceph_cap_string(got), ret);
> + ceph_put_cap_refs_async(ci, got);
> +out_free:
> + ceph_free_cap_flush(prealloc_cf);
> + if (err < 0)
> + ret = vmf_error(err);
> + return ret;
> +}
> diff --git a/fs/ceph/super.h b/fs/ceph/super.h
> index 14784ad86670..acd5c4821ded 100644
> --- a/fs/ceph/super.h
> +++ b/fs/ceph/super.h
> @@ -470,7 +470,7 @@ struct ceph_inode_info {
> #endif
> };
>
> -struct ceph_netfs_request_data {
> +struct ceph_netfs_request_data { // TODO: Remove
> int caps;
>
> /*
> @@ -483,6 +483,29 @@ struct ceph_netfs_request_data {
> bool file_ra_disabled;
> };
>
> +struct ceph_io_request {
> + struct netfs_io_request rreq;
> + u64 rmw_assert_version;
> + int caps;
> +
> + /*
> + * Maximum size of a file readahead request.
> + * The fadvise could update the bdi's default ra_pages.
> + */
> + unsigned int file_ra_pages;
> +
> + /* Set it if fadvise disables file readahead entirely */
> + bool file_ra_disabled;
> +};
> +
> +struct ceph_io_subrequest {
> + union {
> + struct netfs_io_subrequest sreq;
> + struct ceph_io_request *creq;
> + };
> + struct ceph_osd_request *req;
> +};
> +
> static inline struct ceph_inode_info *
> ceph_inode(const struct inode *inode)
> {
> @@ -1237,8 +1260,10 @@ extern void __ceph_touch_fmode(struct ceph_inode_info *ci,
> struct ceph_mds_client *mdsc, int fmode);
>
> /* addr.c */
> -extern const struct address_space_operations ceph_aops;
> +#if 0 // TODO: Remove after netfs conversion
> extern const struct netfs_request_ops ceph_netfs_ops;
> +#endif // TODO: Remove after netfs conversion
> +bool ceph_dirty_folio(struct address_space *mapping, struct folio *folio);
> extern int ceph_mmap(struct file *file, struct vm_area_struct *vma);
> extern int ceph_uninline_data(struct file *file);
> extern int ceph_pool_perm_check(struct inode *inode, int need);
> @@ -1253,6 +1278,14 @@ static inline bool ceph_has_inline_data(struct ceph_inode_info *ci)
> return true;
> }
>
> +/* rdwr.c */
> +extern const struct netfs_request_ops ceph_netfs_ops;
> +extern const struct address_space_operations ceph_aops;
> +
> +ssize_t ceph_netfs_read_iter(struct kiocb *iocb, struct iov_iter *to);
> +ssize_t ceph_netfs_write_iter(struct kiocb *iocb, struct iov_iter *from);
> +vm_fault_t ceph_page_mkwrite(struct vm_fault *vmf);
> +
> /* file.c */
> extern const struct file_operations ceph_file_fops;
>
> @@ -1260,9 +1293,11 @@ extern int ceph_renew_caps(struct inode *inode, int fmode);
> extern int ceph_open(struct inode *inode, struct file *file);
> extern int ceph_atomic_open(struct inode *dir, struct dentry *dentry,
> struct file *file, unsigned flags, umode_t mode);
> +#if 0 // TODO: Remove after netfs conversion
> extern ssize_t __ceph_sync_read(struct inode *inode, loff_t *ki_pos,
> struct iov_iter *to, int *retry_op,
> u64 *last_objver);
> +#endif
> extern int ceph_release(struct inode *inode, struct file *filp);
> extern void ceph_fill_inline_data(struct inode *inode, struct page *locked_page,
> char *data, size_t len);
> diff --git a/fs/netfs/internal.h b/fs/netfs/internal.h
> index 9724d5a1ddc7..a82eb3be9737 100644
> --- a/fs/netfs/internal.h
> +++ b/fs/netfs/internal.h
> @@ -264,9 +264,9 @@ static inline bool netfs_is_cache_enabled(struct netfs_inode *ctx)
> }
>
> /*
> - * Check to see if a buffer aligns with the crypto block size. If it doesn't
> - * the crypto layer is going to copy all the data - in which case relying on
> - * the crypto op for a free copy is pointless.
> + * Check to see if a buffer aligns with the crypto unit block size. If it
> + * doesn't the crypto layer is going to copy all the data - in which case
> + * relying on the crypto op for a free copy is pointless.
> */
> static inline bool netfs_is_crypto_aligned(struct netfs_io_request *rreq,
> struct iov_iter *iter)
> diff --git a/fs/netfs/main.c b/fs/netfs/main.c
> index 0900dea53e4a..d431ba261920 100644
> --- a/fs/netfs/main.c
> +++ b/fs/netfs/main.c
> @@ -139,7 +139,7 @@ static int __init netfs_init(void)
> goto error_folio_pool;
>
> netfs_request_slab = kmem_cache_create("netfs_request",
> - sizeof(struct netfs_io_request), 0,
> + NETFS_DEF_IO_REQUEST_SIZE, 0,
> SLAB_HWCACHE_ALIGN | SLAB_ACCOUNT,
> NULL);
> if (!netfs_request_slab)
> @@ -149,7 +149,7 @@ static int __init netfs_init(void)
> goto error_reqpool;
>
> netfs_subrequest_slab = kmem_cache_create("netfs_subrequest",
> - sizeof(struct netfs_io_subrequest) + 16, 0,
> + NETFS_DEF_IO_SUBREQUEST_SIZE, 0,
> SLAB_HWCACHE_ALIGN | SLAB_ACCOUNT,
> NULL);
> if (!netfs_subrequest_slab)
> diff --git a/fs/netfs/write_issue.c b/fs/netfs/write_issue.c
> index 9b8d99477405..091328596533 100644
> --- a/fs/netfs/write_issue.c
> +++ b/fs/netfs/write_issue.c
> @@ -652,7 +652,8 @@ int netfs_writepages_group(struct address_space *mapping,
> if (netfs_folio_group(folio) != NETFS_FOLIO_COPY_TO_CACHE &&
> unlikely(!test_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags))) {
> set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags);
> - wreq->netfs_ops->begin_writeback(wreq);
> + if (wreq->netfs_ops->begin_writeback)
> + wreq->netfs_ops->begin_writeback(wreq);
> }
>
> error = netfs_write_folio(wreq, wbc, folio);
> @@ -967,7 +968,8 @@ int netfs_writeback_single(struct address_space *mapping,
> trace_netfs_write(wreq, netfs_write_trace_writeback);
> netfs_stat(&netfs_n_wh_writepages);
>
> - if (__test_and_set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags))
> + if (__test_and_set_bit(NETFS_RREQ_UPLOAD_TO_SERVER, &wreq->flags) &&
> + wreq->netfs_ops->begin_writeback)
> wreq->netfs_ops->begin_writeback(wreq);
>
> for (fq = (struct folio_queue *)iter->folioq; fq; fq = fq->next) {
> diff --git a/include/linux/ceph/libceph.h b/include/linux/ceph/libceph.h
> index 733e7f93db66..0c626a7d32f4 100644
> --- a/include/linux/ceph/libceph.h
> +++ b/include/linux/ceph/libceph.h
> @@ -16,6 +16,7 @@
> #include <linux/writeback.h>
> #include <linux/slab.h>
> #include <linux/refcount.h>
> +#include <linux/netfs.h>
>
> #include <linux/ceph/types.h>
> #include <linux/ceph/messenger.h>
> @@ -161,7 +162,7 @@ static inline bool ceph_msgr2(struct ceph_client *client)
> * dirtied.
> */
> struct ceph_snap_context {
> - refcount_t nref;
> + struct netfs_group group;
> u64 seq;
> u32 num_snaps;
> u64 snaps[];
> diff --git a/include/linux/ceph/osd_client.h b/include/linux/ceph/osd_client.h
> index 7eff589711cc..7f8d28b2c41b 100644
> --- a/include/linux/ceph/osd_client.h
> +++ b/include/linux/ceph/osd_client.h
> @@ -246,6 +246,7 @@ struct ceph_osd_request {
> struct completion r_completion; /* private to osd_client.c */
> ceph_osdc_callback_t r_callback;
>
> + struct netfs_io_subrequest *r_subreq;
> struct inode *r_inode; /* for use by callbacks */
> struct list_head r_private_item; /* ditto */
> void *r_priv; /* ditto */
> diff --git a/include/linux/netfs.h b/include/linux/netfs.h
> index 4049c985b9b4..3253352fcbfa 100644
> --- a/include/linux/netfs.h
> +++ b/include/linux/netfs.h
> @@ -26,6 +26,14 @@ enum netfs_sreq_ref_trace;
> typedef struct mempool_s mempool_t;
> struct folio_queue;
>
> +/*
> + * Size of allocations for default netfs_io_(sub)request object slabs and
> + * mempools. If a filesystem's request and subrequest objects fit within this
> + * size, they can use these otherwise they must provide their own.
> + */
> +#define NETFS_DEF_IO_REQUEST_SIZE (sizeof(struct netfs_io_request) + 24)

Why do we hardcode 24 here? What's about named constant? And why namely 24?

> +#define NETFS_DEF_IO_SUBREQUEST_SIZE (sizeof(struct netfs_io_subrequest) + 16)

The same question about 16.

Thanks,
Slava.

> +
> /**
> * folio_start_private_2 - Start an fscache write on a folio. [DEPRECATED]
> * @folio: The folio.
> @@ -184,7 +192,10 @@ struct netfs_io_subrequest {
> struct list_head rreq_link; /* Link in req/stream::subrequests */
> struct list_head ioq_link; /* Link in io_stream::io_queue */
> union {
> - struct iov_iter io_iter; /* Iterator for this subrequest */
> + struct {
> + struct iov_iter io_iter; /* Iterator for this subrequest */
> + void *fs_private; /* Filesystem specific */
> + };
> struct {
> struct scatterlist src_sg; /* Source for crypto subreq */
> struct scatterlist dst_sg; /* Dest for crypto subreq */
> diff --git a/net/ceph/snapshot.c b/net/ceph/snapshot.c
> index e24315937c45..92f63cbca183 100644
> --- a/net/ceph/snapshot.c
> +++ b/net/ceph/snapshot.c
> @@ -17,6 +17,11 @@
> * the entire structure is freed.
> */
>
> +static void ceph_snap_context_kfree(struct netfs_group *group)
> +{
> + kfree(group);
> +}
> +
> /*
> * Create a new ceph snapshot context large enough to hold the
> * indicated number of snapshot ids (which can be 0). Caller has
> @@ -36,8 +41,9 @@ struct ceph_snap_context *ceph_create_snap_context(u32 snap_count,
> if (!snapc)
> return NULL;
>
> - refcount_set(&snapc->nref, 1);
> - snapc->num_snaps = snap_count;
> + refcount_set(&snapc->group.ref, 1);
> + snapc->group.free = ceph_snap_context_kfree;
> + snapc->num_snaps = snap_count;
>
> return snapc;
> }
> @@ -46,18 +52,14 @@ EXPORT_SYMBOL(ceph_create_snap_context);
> struct ceph_snap_context *ceph_get_snap_context(struct ceph_snap_context *sc)
> {
> if (sc)
> - refcount_inc(&sc->nref);
> + netfs_get_group(&sc->group);
> return sc;
> }
> EXPORT_SYMBOL(ceph_get_snap_context);
>
> void ceph_put_snap_context(struct ceph_snap_context *sc)
> {
> - if (!sc)
> - return;
> - if (refcount_dec_and_test(&sc->nref)) {
> - /*printk(" deleting snap_context %p\n", sc);*/
> - kfree(sc);
> - }
> + if (sc)
> + netfs_put_group(&sc->group);
> }
> EXPORT_SYMBOL(ceph_put_snap_context);
>

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