[RFC PATCH 26/35] ceph: Kill ceph_rw_context

David Howells
2025-03-13T23:35:32Z

With all invokers of readahead:

- read() and co.
- splice()
- fadvise(POSIX_FADV_WILLNEED)
- madvise(MADV_WILLNEED)
- fault-in

now getting the FILE_CACHE cap or the LAZYIO cap and holding it across
readahead invocation, there's no need for the ceph_rw_context. It can be
assumed that we have one or other cap - and apparently it doesn't matter
which as we don't actually check rw_ctx->caps.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Viacheslav Dubeyko <slava@dubeyko.com>
cc: Alex Markuze <amarkuze@redhat.com>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: ceph-devel@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
---
fs/ceph/addr.c | 19 +++++++------------
fs/ceph/file.c | 13 +------------
fs/ceph/super.h | 47 -----------------------------------------------
3 files changed, 8 insertions(+), 71 deletions(-)

diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c
index 7c89cafcb91a..27f27ab24446 100644
--- a/fs/ceph/addr.c
+++ b/fs/ceph/addr.c
@@ -473,18 +473,16 @@ static int ceph_init_request(struct netfs_io_request *rreq, struct file *file)
if (!priv)
return -ENOMEM;

+ /*
+ * 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) {
- struct ceph_rw_context *rw_ctx;
- struct ceph_file_info *fi = file->private_data;
-
priv->file_ra_pages = file->f_ra.ra_pages;
priv->file_ra_disabled = file->f_mode & FMODE_RANDOM;
-
- rw_ctx = ceph_find_rw_context(fi);
- if (rw_ctx) {
- rreq->netfs_priv = priv;
- return 0;
- }
+ rreq->netfs_priv = priv;
+ return 0;
}

/*
@@ -1982,10 +1980,7 @@ static vm_fault_t ceph_filemap_fault(struct vm_fault *vmf)

if ((got & (CEPH_CAP_FILE_CACHE | CEPH_CAP_FILE_LAZYIO)) ||
!ceph_has_inline_data(ci)) {
- CEPH_DEFINE_RW_CONTEXT(rw_ctx, got);
- ceph_add_rw_context(fi, &rw_ctx);
ret = filemap_fault(vmf);
- ceph_del_rw_context(fi, &rw_ctx);
doutc(cl, "%llx.%llx %llu drop cap refs %s ret %x\n",
ceph_vinop(inode), off, ceph_cap_string(got), ret);
} else
diff --git a/fs/ceph/file.c b/fs/ceph/file.c
index b876cecbaba5..4512215cccc6 100644
--- a/fs/ceph/file.c
+++ b/fs/ceph/file.c
@@ -229,8 +229,6 @@ static int ceph_init_file_info(struct inode *inode, struct file *file,
ceph_get_fmode(ci, fmode, 1);
fi->fmode = fmode;

- spin_lock_init(&fi->rw_contexts_lock);
- INIT_LIST_HEAD(&fi->rw_contexts);
fi->filp_gen = READ_ONCE(ceph_inode_to_fs_client(inode)->filp_gen);

if ((file->f_mode & FMODE_WRITE) && ceph_has_inline_data(ci)) {
@@ -999,7 +997,6 @@ int ceph_release(struct inode *inode, struct file *file)
struct ceph_dir_file_info *dfi = file->private_data;
doutc(cl, "%p %llx.%llx dir file %p\n", inode,
ceph_vinop(inode), file);
- WARN_ON(!list_empty(&dfi->file_info.rw_contexts));

ceph_put_fmode(ci, dfi->file_info.fmode, 1);

@@ -1012,7 +1009,6 @@ int ceph_release(struct inode *inode, struct file *file)
struct ceph_file_info *fi = file->private_data;
doutc(cl, "%p %llx.%llx regular file %p\n", inode,
ceph_vinop(inode), file);
- WARN_ON(!list_empty(&fi->rw_contexts));

ceph_fscache_unuse_cookie(inode, file->f_mode & FMODE_WRITE);
ceph_put_fmode(ci, fi->fmode, 1);
@@ -2154,13 +2150,10 @@ static ssize_t ceph_read_iter(struct kiocb *iocb, struct iov_iter *to)
retry_op = READ_INLINE;
}
} else {
- CEPH_DEFINE_RW_CONTEXT(rw_ctx, got);
doutc(cl, "async %p %llx.%llx %llu~%u got cap refs on %s\n",
inode, ceph_vinop(inode), iocb->ki_pos, (unsigned)len,
ceph_cap_string(got));
- ceph_add_rw_context(fi, &rw_ctx);
ret = generic_file_read_iter(iocb, to);
- ceph_del_rw_context(fi, &rw_ctx);
}

doutc(cl, "%p %llx.%llx dropping cap refs on %s = %d\n",
@@ -2256,7 +2249,6 @@ static ssize_t ceph_splice_read(struct file *in, loff_t *ppos,
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);
@@ -2291,10 +2283,7 @@ static ssize_t ceph_splice_read(struct file *in, loff_t *ppos,
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);
@@ -3177,7 +3166,7 @@ static int ceph_fadvise(struct file *file, loff_t offset, loff_t len, int advice
goto out;
}

- if ((got & want) == want) {
+ if (got & want) {
doutc(cl, "fadvise(WILLNEED) %p %llx.%llx %llu~%llu got cap refs on %s\n",
inode, ceph_vinop(inode), offset, len,
ceph_cap_string(got));
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index b072572e2cf4..14784ad86670 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -833,10 +833,6 @@ extern void change_auth_cap_ses(struct ceph_inode_info *ci,
struct ceph_file_info {
short fmode; /* initialized on open */
short flags; /* CEPH_F_* */
-
- spinlock_t rw_contexts_lock;
- struct list_head rw_contexts;
-
u32 filp_gen;
};

@@ -859,49 +855,6 @@ struct ceph_dir_file_info {
int dir_info_len;
};

-struct ceph_rw_context {
- struct list_head list;
- struct task_struct *thread;
- int caps;
-};
-
-#define CEPH_DEFINE_RW_CONTEXT(_name, _caps) \
- struct ceph_rw_context _name = { \
- .thread = current, \
- .caps = _caps, \
- }
-
-static inline void ceph_add_rw_context(struct ceph_file_info *cf,
- struct ceph_rw_context *ctx)
-{
- spin_lock(&cf->rw_contexts_lock);
- list_add(&ctx->list, &cf->rw_contexts);
- spin_unlock(&cf->rw_contexts_lock);
-}
-
-static inline void ceph_del_rw_context(struct ceph_file_info *cf,
- struct ceph_rw_context *ctx)
-{
- spin_lock(&cf->rw_contexts_lock);
- list_del(&ctx->list);
- spin_unlock(&cf->rw_contexts_lock);
-}
-
-static inline struct ceph_rw_context*
-ceph_find_rw_context(struct ceph_file_info *cf)
-{
- struct ceph_rw_context *ctx, *found = NULL;
- spin_lock(&cf->rw_contexts_lock);
- list_for_each_entry(ctx, &cf->rw_contexts, list) {
- if (ctx->thread == current) {
- found = ctx;
- break;
- }
- }
- spin_unlock(&cf->rw_contexts_lock);
- return found;
-}
-
struct ceph_readdir_cache_control {
struct folio *folio;
struct dentry **dentries;