]> git-server-git.apps.pok.os.sepia.ceph.com Git - ceph-client.git/commitdiff
ceph: file operations
authorSage Weil <sage@newdream.net>
Tue, 19 May 2009 21:45:29 +0000 (14:45 -0700)
committerSage Weil <sage@newdream.net>
Tue, 19 May 2009 21:45:29 +0000 (14:45 -0700)
File open and close operations, and read and write methods that ensure
we have obtained the proper capabilities from the MDS cluster before
performing IO on a file.  We take references on held capabilities for
the duration of the read/write to avoid prematurely releasing them
back to the MDS.

fs/ceph/file.c [new file with mode: 0644]

diff --git a/fs/ceph/file.c b/fs/ceph/file.c
new file mode 100644 (file)
index 0000000..98a92c2
--- /dev/null
@@ -0,0 +1,815 @@
+
+#include <linux/sched.h>
+#include <linux/file.h>
+#include <linux/writeback.h>
+
+#include "ceph_debug.h"
+
+int ceph_debug_file __read_mostly = -1;
+#define DOUT_MASK DOUT_MASK_FILE
+#define DOUT_VAR ceph_debug_file
+#include "super.h"
+
+#include "mds_client.h"
+
+#include <linux/namei.h>
+
+
+/*
+ * Prepare an open request.  Preallocate ceph_cap to avoid an
+ * inopportune ENOMEM later.
+ */
+static struct ceph_mds_request *
+prepare_open_request(struct super_block *sb, int flags, int create_mode)
+{
+       struct ceph_client *client = ceph_sb_to_client(sb);
+       struct ceph_mds_client *mdsc = &client->mdsc;
+       struct ceph_mds_request *req;
+       int want_auth = USE_ANY_MDS;
+       int op = (flags & O_CREAT) ? CEPH_MDS_OP_CREATE : CEPH_MDS_OP_OPEN;
+
+       if (flags & (O_WRONLY|O_RDWR|O_CREAT|O_TRUNC))
+               want_auth = USE_AUTH_MDS;
+
+       req = ceph_mdsc_create_request(mdsc, op, want_auth);
+       if (IS_ERR(req))
+               goto out;
+       req->r_fmode = ceph_flags_to_mode(flags);
+       req->r_args.open.flags = cpu_to_le32(flags);
+       req->r_args.open.mode = cpu_to_le32(create_mode);
+out:
+       return req;
+}
+
+/*
+ * initialize private struct file data.
+ * if we fail, clean up by dropping fmode reference on the ceph_inode
+ */
+static int ceph_init_file(struct inode *inode, struct file *file, int fmode)
+{
+       struct ceph_file_info *cf;
+       int ret = 0;
+
+       switch (inode->i_mode & S_IFMT) {
+       case S_IFREG:
+       case S_IFDIR:
+               dout(20, "init_file %p %p 0%o (regular)\n", inode, file,
+                    inode->i_mode);
+               cf = kzalloc(sizeof(*cf), GFP_NOFS);
+               if (cf == NULL) {
+                       ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
+                       return -ENOMEM;
+               }
+               cf->fmode = fmode;
+               file->private_data = cf;
+               BUG_ON(inode->i_fop->release != ceph_release);
+               break;
+
+       case S_IFLNK:
+               dout(20, "init_file %p %p 0%o (symlink)\n", inode, file,
+                    inode->i_mode);
+               ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
+               break;
+
+       default:
+               dout(20, "init_file %p %p 0%o (special)\n", inode, file,
+                    inode->i_mode);
+               /*
+                * we need to drop the open ref now, since we don't
+                * have .release set to ceph_release.
+                */
+               ceph_put_fmode(ceph_inode(inode), fmode); /* clean up */
+               BUG_ON(inode->i_fop->release == ceph_release);
+
+               /* call the proper open fop */
+               ret = inode->i_fop->open(inode, file);
+       }
+       return ret;
+}
+
+/*
+ * If the filp already has private_data, that means the file was
+ * already opened by intent during lookup, and we do nothing.
+ *
+ * If we already have the requisite capabilities, we can satisfy
+ * the open request locally (no need to request new caps from the
+ * MDS).
+ */
+int ceph_open(struct inode *inode, struct file *file)
+{
+       struct ceph_inode_info *ci = ceph_inode(inode);
+       struct ceph_client *client = ceph_sb_to_client(inode->i_sb);
+       struct ceph_mds_client *mdsc = &client->mdsc;
+       struct ceph_mds_request *req;
+       struct ceph_file_info *cf = file->private_data;
+       struct inode *parent_inode = file->f_dentry->d_parent->d_inode;
+       int err;
+       int flags, fmode, wanted;
+
+       if (cf) {
+               dout(5, "open file %p is already opened\n", file);
+               return 0;
+       }
+
+       /* filter out O_CREAT|O_EXCL; vfs did that already.  yuck. */
+       flags = file->f_flags & ~(O_CREAT|O_EXCL);
+       if (S_ISDIR(inode->i_mode))
+               flags = O_DIRECTORY;  /* mds likes to know */
+
+       dout(5, "open inode %p ino %llx.%llx file %p flags %d (%d)\n", inode,
+            ceph_vinop(inode), file, flags, file->f_flags);
+       fmode = ceph_flags_to_mode(flags);
+       wanted = ceph_caps_for_mode(fmode);
+
+       /* snapped files are read-only */
+       if (ceph_snap(inode) != CEPH_NOSNAP && (file->f_mode & FMODE_WRITE))
+               return -EROFS;
+
+       /* trivially open snapdir */
+       if (ceph_snap(inode) == CEPH_SNAPDIR) {
+               spin_lock(&inode->i_lock);
+               __ceph_get_fmode(ci, fmode);
+               spin_unlock(&inode->i_lock);
+               return ceph_init_file(inode, file, fmode);
+       }
+
+       /*
+        * We re-use existing caps only if already have an open file
+        * that also wants them.  That is, our want for the caps is
+        * registered with the MDS.
+        */
+       spin_lock(&inode->i_lock);
+       if (__ceph_is_any_real_caps(ci)) {
+               int mds_wanted = __ceph_caps_mds_wanted(ci);
+               int issued = __ceph_caps_issued(ci, NULL);
+
+               dout(10, "open %p fmode %d want %s issued %s using existing\n",
+                    inode, fmode, ceph_cap_string(wanted),
+                    ceph_cap_string(issued));
+               __ceph_get_fmode(ci, fmode);
+               spin_unlock(&inode->i_lock);
+
+               /* adjust wanted? */
+               if ((issued & wanted) != wanted &&
+                   (mds_wanted & wanted) != wanted &&
+                   ceph_snap(inode) != CEPH_SNAPDIR)
+                       ceph_check_caps(ci, 0, NULL);
+
+               return ceph_init_file(inode, file, fmode);
+       } else if (ceph_snap(inode) != CEPH_NOSNAP &&
+                  (ci->i_snap_caps & wanted) == wanted) {
+               __ceph_get_fmode(ci, fmode);
+               spin_unlock(&inode->i_lock);
+               return ceph_init_file(inode, file, fmode);
+       }
+       spin_unlock(&inode->i_lock);
+
+       dout(10, "open fmode %d wants %s\n", fmode, ceph_cap_string(wanted));
+       req = prepare_open_request(inode->i_sb, flags, 0);
+       if (IS_ERR(req)) {
+               err = PTR_ERR(req);
+               goto out;
+       }
+       req->r_inode = igrab(inode);
+       req->r_num_caps = 1;
+       err = ceph_mdsc_do_request(mdsc, parent_inode, req);
+       if (!err)
+               err = ceph_init_file(inode, file, req->r_fmode);
+       ceph_mdsc_put_request(req);
+       dout(5, "open result=%d on %llx.%llx\n", err, ceph_vinop(inode));
+out:
+       return err;
+}
+
+
+/*
+ * Do a lookup + open with a single request.
+ *
+ * If this succeeds, but some subsequent check in the vfs
+ * may_open() fails, the struct *file gets cleaned up (i.e.
+ * ceph_release gets called).  So fear not!
+ */
+/*
+ * flags
+ *  path_lookup_open   -> LOOKUP_OPEN
+ *  path_lookup_create -> LOOKUP_OPEN|LOOKUP_CREATE
+ */
+struct dentry *ceph_lookup_open(struct inode *dir, struct dentry *dentry,
+                               struct nameidata *nd, int mode,
+                               int locked_dir)
+{
+       struct ceph_client *client = ceph_sb_to_client(dir->i_sb);
+       struct ceph_mds_client *mdsc = &client->mdsc;
+       struct file *file = nd->intent.open.file;
+       struct inode *parent_inode = get_dentry_parent_inode(file->f_dentry);
+       struct ceph_mds_request *req;
+       int err;
+       int flags = nd->intent.open.flags - 1;  /* silly vfs! */
+
+       dout(5, "ceph_lookup_open dentry %p '%.*s' flags %d mode 0%o\n",
+            dentry, dentry->d_name.len, dentry->d_name.name, flags, mode);
+
+       /* do the open */
+       req = prepare_open_request(dir->i_sb, flags, mode);
+       if (IS_ERR(req))
+               return ERR_PTR(PTR_ERR(req));
+       req->r_dentry = dget(dentry);
+       req->r_num_caps = 2;
+       if (flags & O_CREAT) {
+               req->r_dentry_drop = CEPH_CAP_FILE_SHARED;
+               req->r_dentry_unless = CEPH_CAP_FILE_EXCL;
+       }
+       req->r_locked_dir = dir;           /* caller holds dir->i_mutex */
+       err = ceph_mdsc_do_request(mdsc, parent_inode, req);
+       dentry = ceph_finish_lookup(req, dentry, err);
+       if (!err && (flags & O_CREAT) && !req->r_reply_info.head->is_dentry)
+               err = ceph_handle_notrace_create(dir, dentry);
+       if (!err)
+               err = ceph_init_file(req->r_dentry->d_inode, file,
+                                    req->r_fmode);
+       ceph_mdsc_put_request(req);
+       dout(5, "ceph_lookup_open result=%p\n", dentry);
+       return dentry;
+}
+
+int ceph_release(struct inode *inode, struct file *file)
+{
+       struct ceph_inode_info *ci = ceph_inode(inode);
+       struct ceph_file_info *cf = file->private_data;
+
+       dout(5, "release inode %p file %p\n", inode, file);
+       ceph_put_fmode(ci, cf->fmode);
+       if (cf->last_readdir)
+               ceph_mdsc_put_request(cf->last_readdir);
+       kfree(cf->last_name);
+       kfree(cf->dir_info);
+       dput(cf->dentry);
+       kfree(cf);
+       return 0;
+}
+
+/*
+ * build a vector of user pages
+ */
+static struct page **get_direct_page_vector(const char __user *data,
+                                           int num_pages,
+                                           loff_t off, size_t len)
+{
+       struct page **pages;
+       int rc;
+
+       pages = kmalloc(sizeof(*pages) * num_pages, GFP_NOFS);
+       if (!pages)
+               return ERR_PTR(-ENOMEM);
+
+       down_read(&current->mm->mmap_sem);
+       rc = get_user_pages(current, current->mm, (unsigned long)data,
+                           num_pages, 0, 0, pages, NULL);
+       up_read(&current->mm->mmap_sem);
+       if (rc < 0)
+               goto fail;
+       return pages;
+
+fail:
+       kfree(pages);
+       return ERR_PTR(rc);
+}
+
+static void put_page_vector(struct page **pages, int num_pages)
+{
+       int i;
+
+       for (i = 0; i < num_pages; i++)
+               put_page(pages[i]);
+       kfree(pages);
+}
+
+void ceph_release_page_vector(struct page **pages, int num_pages)
+{
+       int i;
+
+       for (i = 0; i < num_pages; i++)
+               __free_pages(pages[i], 0);
+       kfree(pages);
+}
+
+static struct page **alloc_page_vector(int num_pages)
+{
+       struct page **pages;
+       int i;
+
+       pages = kmalloc(sizeof(*pages) * num_pages, GFP_NOFS);
+       if (!pages)
+               return ERR_PTR(-ENOMEM);
+       for (i = 0; i < num_pages; i++) {
+               pages[i] = alloc_page(GFP_NOFS);
+               if (pages[i] == NULL) {
+                       ceph_release_page_vector(pages, i);
+                       return ERR_PTR(-ENOMEM);
+               }
+       }
+       return pages;
+}
+
+/*
+ * copy user data into a page vector
+ */
+static int copy_user_to_page_vector(struct page **pages,
+                                   const char __user *data,
+                                   loff_t off, size_t len)
+{
+       int i = 0;
+       int po = off & ~PAGE_CACHE_MASK;
+       int left = len;
+       int l, bad;
+
+       while (left > 0) {
+               l = min_t(int, PAGE_SIZE-po, left);
+               bad = copy_from_user(page_address(pages[i]) + po, data, l);
+               if (bad == l)
+                       return -EFAULT;
+               data += l - bad;
+               left -= l - bad;
+               if (po) {
+                       po += l - bad;
+                       if (po == PAGE_CACHE_SIZE)
+                               po = 0;
+               }
+       }
+       return len;
+}
+
+/*
+ * copy user data from a page vector into a user pointer
+ */
+static int copy_page_vector_to_user(struct page **pages, char __user *data,
+                                   loff_t off, size_t len)
+{
+       int i = 0;
+       int po = off & ~PAGE_CACHE_MASK;
+       int left = len;
+       int l, bad;
+
+       while (left > 0) {
+               l = min_t(int, left, PAGE_CACHE_SIZE-po);
+               bad = copy_to_user(data, page_address(pages[i]) + po, l);
+               if (bad == l)
+                       return -EFAULT;
+               data += l - bad;
+               left -= l - bad;
+               if (po) {
+                       po += l - bad;
+                       if (po == PAGE_CACHE_SIZE)
+                               po = 0;
+               }
+               i++;
+       }
+       return len;
+}
+
+/*
+ * Completely synchronous read and write methods.  Direct from __user
+ * buffer to osd.
+ *
+ * If read spans object boundary, just do multiple reads.
+ *
+ * FIXME: for a correct atomic read, we should take read locks on all
+ * objects.
+ */
+static ssize_t ceph_sync_read(struct file *file, char __user *data,
+                             unsigned left, loff_t *offset)
+{
+       struct inode *inode = file->f_dentry->d_inode;
+       struct ceph_inode_info *ci = ceph_inode(inode);
+       struct ceph_client *client = ceph_inode_to_client(inode);
+       long long unsigned start_off = *offset;
+       long long unsigned pos = start_off;
+       struct page **pages, **page_pos;
+       int num_pages = calc_pages_for(start_off, left);
+       int pages_left;
+       int read = 0;
+       int ret;
+
+       dout(10, "sync_read on file %p %llu~%u %s\n", file, start_off, left,
+            (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");
+
+       if (file->f_flags & O_DIRECT) {
+               pages = get_direct_page_vector(data, num_pages, pos, left);
+
+               /*
+                * flush any page cache pages in this range.  this
+                * will make concurrent normal and O_DIRECT io slow,
+                * but it will at least behave sensibly when they are
+                * in sequence.
+                */
+               filemap_write_and_wait(inode->i_mapping);
+       } else {
+               pages = alloc_page_vector(num_pages);
+       }
+       if (IS_ERR(pages))
+               return PTR_ERR(pages);
+
+       /*
+        * we may need to do multiple reads.  not atomic, unfortunately.
+        */
+       page_pos = pages;
+       pages_left = num_pages;
+
+more:
+       ret = ceph_osdc_readpages(&client->osdc, ceph_vino(inode),
+                                 &ci->i_layout,
+                                 pos, left, ci->i_truncate_seq,
+                                 ci->i_truncate_size,
+                                 page_pos, pages_left);
+       if (ret > 0) {
+               int didpages =
+                       ((pos & ~PAGE_CACHE_MASK) + ret) >> PAGE_CACHE_SHIFT;
+
+               pos += ret;
+               read += ret;
+               left -= ret;
+               if (left) {
+                       page_pos += didpages;
+                       pages_left -= didpages;
+                       goto more;
+               }
+
+               ret = copy_page_vector_to_user(pages, data, start_off, read);
+               if (ret == 0)
+                       *offset = start_off + read;
+       }
+
+       if (file->f_flags & O_DIRECT)
+               put_page_vector(pages, num_pages);
+       else
+               ceph_release_page_vector(pages, num_pages);
+       return ret;
+}
+
+/*
+ * Write commit callback, called if we requested both an ACK and
+ * ONDISK commit reply from the OSD.
+ */
+static void sync_write_commit(struct ceph_osd_request *req)
+{
+       struct ceph_inode_info *ci = ceph_inode(req->r_inode);
+
+       dout(10, "sync_write_commit %p tid %llu\n", req, req->r_tid);
+       spin_lock(&ci->i_unsafe_lock);
+       list_del_init(&req->r_unsafe_item);
+       spin_unlock(&ci->i_unsafe_lock);
+       ceph_put_cap_refs(ci, CEPH_CAP_FILE_WR);
+}
+
+/*
+ * Wait on any unsafe replies for the given inode.  First wait on the
+ * newest request, and make that the upper bound.  Then, if there are
+ * more requests, keep waiting on the oldest as long as it is still older
+ * than the original request.
+ */
+static void sync_write_wait(struct inode *inode)
+{
+       struct ceph_inode_info *ci = ceph_inode(inode);
+       struct list_head *head = &ci->i_unsafe_writes;
+       struct ceph_osd_request *req;
+       u64 last_tid;
+
+       spin_lock(&ci->i_unsafe_lock);
+       if (list_empty(head))
+               goto out;
+
+       /* set upper bound as _last_ entry in chain */
+       req = list_entry(head->prev, struct ceph_osd_request,
+                        r_unsafe_item);
+       last_tid = req->r_tid;
+
+       do {
+               ceph_osdc_get_request(req);
+               spin_unlock(&ci->i_unsafe_lock);
+               dout(10, "sync_write_wait on tid %llu (until %llu)\n",
+                    req->r_tid, last_tid);
+               wait_for_completion(&req->r_safe_completion);
+               spin_lock(&ci->i_unsafe_lock);
+               ceph_osdc_put_request(req);
+
+               /*
+                * from here on look at first entry in chain, since we
+                * only want to wait for anything older than last_tid
+                */
+               if (list_empty(head))
+                       break;
+               req = list_entry(head->next, struct ceph_osd_request,
+                                r_unsafe_item);
+       } while (req->r_tid < last_tid);
+out:
+       spin_unlock(&ci->i_unsafe_lock);
+}
+
+/*
+ * synchronous write.  from userspace.
+ *
+ * FIXME: if write spans object boundary, just do two separate write.
+ * for a correct atomic write, we should take write locks on all
+ * objects, rollback on failure, etc.
+ */
+static ssize_t ceph_sync_write(struct file *file, const char __user *data,
+                              size_t left, loff_t *offset)
+{
+       struct inode *inode = file->f_dentry->d_inode;
+       struct ceph_inode_info *ci = ceph_inode(inode);
+       struct ceph_client *client = ceph_inode_to_client(inode);
+       struct ceph_osd_request *req;
+       struct page **pages;
+       int num_pages;
+       long long unsigned pos;
+       u64 len;
+       int written = 0;
+       int flags;
+       int do_sync = 0;
+       int ret;
+       struct timespec mtime = CURRENT_TIME;
+
+       if (ceph_snap(file->f_dentry->d_inode) != CEPH_NOSNAP)
+               return -EROFS;
+
+       dout(10, "sync_write on file %p %lld~%u %s\n", file, *offset,
+            (unsigned)left, (file->f_flags & O_DIRECT) ? "O_DIRECT" : "");
+
+       if (file->f_flags & O_APPEND)
+               pos = i_size_read(inode);
+       else
+               pos = *offset;
+
+       flags = CEPH_OSD_FLAG_ORDERSNAP |
+               CEPH_OSD_FLAG_ONDISK |
+               CEPH_OSD_FLAG_MODIFY;
+       if ((file->f_flags & (O_SYNC|O_DIRECT)) == 0)
+               flags |= CEPH_OSD_FLAG_ACK;
+       else
+               do_sync = 1;
+
+       /*
+        * we may need to do multiple writes here if we span an object
+        * boundary.  this isn't atomic, unfortunately.  :(
+        */
+more:
+       len = left;
+       req = ceph_osdc_new_request(&client->osdc, &ci->i_layout,
+                                   ceph_vino(inode), pos, &len,
+                                   CEPH_OSD_OP_WRITE, flags,
+                                   ci->i_snap_realm->cached_context,
+                                   do_sync,
+                                   ci->i_truncate_seq, ci->i_truncate_size,
+                                   &mtime);
+       if (IS_ERR(req))
+               return PTR_ERR(req);
+
+       num_pages = calc_pages_for(pos, len);
+
+       if (file->f_flags & O_DIRECT) {
+               pages = get_direct_page_vector(data, num_pages, pos, len);
+               if (IS_ERR(pages)) {
+                       ret = PTR_ERR(pages);
+                       goto out;
+               }
+
+               /*
+                * throw out any page cache pages in this range. this
+                * may block.
+                */
+               truncate_inode_pages_range(inode->i_mapping, pos, pos+len);
+       } else {
+               pages = alloc_page_vector(num_pages);
+               if (IS_ERR(pages)) {
+                       ret = PTR_ERR(pages);
+                       goto out;
+               }
+               ret = copy_user_to_page_vector(pages, data, pos, len);
+               if (ret < 0) {
+                       ceph_release_page_vector(pages, num_pages);
+                       goto out;
+               }
+
+               if ((file->f_flags & O_SYNC) == 0) {
+                       /* get a second commit callback */
+                       req->r_safe_callback = sync_write_commit;
+                       req->r_own_pages = 1;
+               }
+       }
+       req->r_pages = pages;
+       req->r_num_pages = num_pages;
+       req->r_inode = inode;
+
+       ret = ceph_osdc_start_request(&client->osdc, req);
+       if (!ret) {
+               if (req->r_safe_callback) {
+                       /*
+                        * Add to inode unsafe list only after we
+                        * start_request so that a tid has been assigned.
+                        */
+                       spin_lock(&ci->i_unsafe_lock);
+                       list_add(&ci->i_unsafe_writes, &req->r_unsafe_item);
+                       spin_unlock(&ci->i_unsafe_lock);
+                       ceph_get_cap_refs(ci, CEPH_CAP_FILE_WR);
+               }
+               ret = ceph_osdc_wait_request(&client->osdc, req);
+       }
+
+       if (file->f_flags & O_DIRECT)
+               put_page_vector(pages, num_pages);
+       else if (file->f_flags & O_SYNC)
+               ceph_release_page_vector(pages, num_pages);
+
+out:
+       ceph_osdc_put_request(req);
+       if (ret == 0) {
+               pos += len;
+               written += len;
+               left -= len;
+               if (left)
+                       goto more;
+
+               ret = written;
+               *offset = pos;
+               if (pos > i_size_read(inode))
+                       ceph_inode_set_size(inode, pos);
+       }
+       return ret;
+}
+
+/*
+ * 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?
+ */
+static ssize_t ceph_aio_read(struct kiocb *iocb, const struct iovec *iov,
+                            unsigned long nr_segs, loff_t pos)
+{
+       struct file *filp = iocb->ki_filp;
+       loff_t *ppos = &iocb->ki_pos;
+       size_t len = iov->iov_len;
+       struct inode *inode = filp->f_dentry->d_inode;
+       struct ceph_inode_info *ci = ceph_inode(inode);
+       ssize_t ret;
+       int got = 0;
+
+       dout(10, "aio_read %llx.%llx %llu~%u trying to get caps on %p\n",
+            ceph_vinop(inode), pos, (unsigned)len, inode);
+       __ceph_do_pending_vmtruncate(inode);
+       ret = ceph_get_caps(ci, CEPH_CAP_FILE_RD, CEPH_CAP_FILE_CACHE,
+                           &got, -1);
+       if (ret < 0)
+               goto out;
+       dout(10, "aio_read %llx.%llx %llu~%u got cap refs on %s\n",
+            ceph_vinop(inode), pos, (unsigned)len, ceph_cap_string(got));
+
+       if ((got & CEPH_CAP_FILE_CACHE) == 0 ||
+           (iocb->ki_filp->f_flags & O_DIRECT) ||
+           (inode->i_sb->s_flags & MS_SYNCHRONOUS))
+               /* hmm, this isn't really async... */
+               ret = ceph_sync_read(filp, iov->iov_base, len, ppos);
+       else
+               ret = generic_file_aio_read(iocb, iov, nr_segs, pos);
+
+out:
+       dout(10, "aio_read %llx.%llx dropping cap refs on %s\n",
+            ceph_vinop(inode), ceph_cap_string(got));
+       ceph_put_cap_refs(ci, got);
+       return ret;
+}
+
+/*
+ * Check the offset we are writing up to against our current
+ * max_size.  If necessary, tell the MDS we want to write to
+ * a larger offset.
+ */
+static void check_max_size(struct inode *inode, loff_t endoff)
+{
+       struct ceph_inode_info *ci = ceph_inode(inode);
+       int check = 0;
+
+       /* do we need to explicitly request a larger max_size? */
+       spin_lock(&inode->i_lock);
+       if ((endoff >= ci->i_max_size ||
+            endoff > (inode->i_size << 1)) &&
+           endoff > ci->i_wanted_max_size) {
+               dout(10, "write %p at large endoff %llu, req max_size\n",
+                    inode, endoff);
+               ci->i_wanted_max_size = endoff;
+               check = 1;
+       }
+       spin_unlock(&inode->i_lock);
+       if (check)
+               ceph_check_caps(ci, CHECK_CAPS_AUTHONLY, NULL);
+}
+
+/*
+ * 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.
+ */
+static ssize_t ceph_aio_write(struct kiocb *iocb, const struct iovec *iov,
+                      unsigned long nr_segs, loff_t pos)
+{
+       struct file *file = iocb->ki_filp;
+       struct address_space *mapping = file->f_mapping;
+       struct inode *inode = file->f_dentry->d_inode;
+       struct ceph_inode_info *ci = ceph_inode(inode);
+       struct ceph_osd_client *osdc = &ceph_client(inode->i_sb)->osdc;
+       loff_t endoff = pos + iov->iov_len;
+       int got = 0;
+       int ret;
+
+       if (ceph_snap(inode) != CEPH_NOSNAP)
+               return -EROFS;
+
+retry_snap:
+       if (ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_FULL))
+               return -ENOSPC;
+       __ceph_do_pending_vmtruncate(inode);
+       check_max_size(inode, endoff);
+       dout(10, "aio_write %p %llu~%u getting caps. i_size %llu\n",
+            inode, pos, (unsigned)iov->iov_len, inode->i_size);
+       ret = ceph_get_caps(ci, CEPH_CAP_FILE_WR, CEPH_CAP_FILE_BUFFER,
+                           &got, endoff);
+       if (ret < 0)
+               goto out;
+
+       dout(10, "aio_write %p %llu~%u  got cap refs on %s\n",
+            inode, pos, (unsigned)iov->iov_len, ceph_cap_string(got));
+
+       if ((got & CEPH_CAP_FILE_BUFFER) == 0 ||
+           (iocb->ki_filp->f_flags & O_DIRECT) ||
+           (inode->i_sb->s_flags & MS_SYNCHRONOUS)) {
+               ret = ceph_sync_write(file, iov->iov_base, iov->iov_len,
+                       &iocb->ki_pos);
+       } else {
+               ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
+
+               if (ret >= 0 &&
+                   ceph_osdmap_flag(osdc->osdmap, CEPH_OSDMAP_NEARFULL))
+                       ret = sync_page_range(inode, mapping, pos, ret);
+       }
+       if (ret >= 0) {
+               spin_lock(&inode->i_lock);
+               __ceph_mark_dirty_caps(ci, CEPH_CAP_FILE_WR);
+               spin_unlock(&inode->i_lock);
+       }
+
+out:
+       dout(10, "aio_write %p %llu~%u  dropping cap refs on %s\n",
+            inode, pos, (unsigned)iov->iov_len, ceph_cap_string(got));
+       ceph_put_cap_refs(ci, got);
+
+       if (ret == -EOLDSNAPC) {
+               dout(10, "aio_write %p %llu~%u got EOLDSNAPC, retrying\n",
+                    inode, pos, (unsigned)iov->iov_len);
+               goto retry_snap;
+       }
+
+       return ret;
+}
+
+static int ceph_fsync(struct file *file, struct dentry *dentry, int datasync)
+{
+       struct inode *inode = dentry->d_inode;
+       int ret;
+
+       dout(10, "fsync %p\n", inode);
+       sync_write_wait(inode);
+
+       ret = filemap_write_and_wait(inode->i_mapping);
+       if (ret < 0)
+               return ret;
+
+       /*
+        * Queue up the cap flush, but don't wait on it: the MDS can
+        * recover from the object size/mtimes.
+        */
+       ceph_write_inode(inode, 0);
+
+       return ret;
+}
+
+const struct file_operations ceph_file_fops = {
+       .open = ceph_open,
+       .release = ceph_release,
+       .llseek = generic_file_llseek,
+       .read = do_sync_read,
+       .write = do_sync_write,
+       .aio_read = ceph_aio_read,
+       .aio_write = ceph_aio_write,
+       .mmap = ceph_mmap,
+       .fsync = ceph_fsync,
+       .splice_read = generic_file_splice_read,
+       .splice_write = generic_file_splice_write,
+       .unlocked_ioctl = ceph_ioctl,
+};
+