diff options
| -rw-r--r-- | fs/nfs/write.c | 201 |
1 files changed, 103 insertions, 98 deletions
diff --git a/fs/nfs/write.c b/fs/nfs/write.c index 21d8a48..04f51e5 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -34,9 +34,6 @@ /* * Local function declarations */ -static struct nfs_page * nfs_update_request(struct nfs_open_context*, - struct page *, - unsigned int, unsigned int); static void nfs_pageio_init_write(struct nfs_pageio_descriptor *desc, struct inode *inode, int ioflags); static void nfs_redirty_request(struct nfs_page *req); @@ -169,30 +166,6 @@ static void nfs_mark_uptodate(struct page *page, unsigned int base, unsigned int SetPageUptodate(page); } -static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page, - unsigned int offset, unsigned int count) -{ - struct nfs_page *req; - int ret; - - for (;;) { - req = nfs_update_request(ctx, page, offset, count); - if (!IS_ERR(req)) - break; - ret = PTR_ERR(req); - if (ret != -EBUSY) - return ret; - ret = nfs_wb_page(page->mapping->host, page); - if (ret != 0) - return ret; - } - /* Update file length */ - nfs_grow_file(page, offset, count); - nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes); - nfs_clear_page_tag_locked(req); - return 0; -} - static int wb_priority(struct writeback_control *wbc) { if (wbc->for_reclaim) @@ -356,11 +329,19 @@ int nfs_writepages(struct address_space *mapping, struct writeback_control *wbc) /* * Insert a write request into an inode */ -static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req) +static int nfs_inode_add_request(struct inode *inode, struct nfs_page *req) { struct nfs_inode *nfsi = NFS_I(inode); int error; + error = radix_tree_preload(GFP_NOFS); + if (error != 0) + goto out; + + /* Lock the request! */ + nfs_lock_request_dontget(req); + + spin_lock(&inode->i_lock); error = radix_tree_insert(&nfsi->nfs_page_tree, req->wb_index, req); BUG_ON(error); if (!nfsi->npages) { @@ -374,6 +355,10 @@ static void nfs_inode_add_request(struct inode *inode, struct nfs_page *req) kref_get(&req->wb_kref); radix_tree_tag_set(&nfsi->nfs_page_tree, req->wb_index, NFS_PAGE_TAG_LOCKED); + spin_unlock(&inode->i_lock); + radix_tree_preload_end(); +out: + return error; } /* @@ -565,101 +550,121 @@ static inline int nfs_scan_commit(struct inode *inode, struct list_head *dst, pg #endif /* - * Try to update any existing write request, or create one if there is none. - * In order to match, the request's credentials must match those of - * the calling process. + * Search for an existing write request, and attempt to update + * it to reflect a new dirty region on a given page. * - * Note: Should always be called with the Page Lock held! + * If the attempt fails, then the existing request is flushed out + * to disk. */ -static struct nfs_page * nfs_update_request(struct nfs_open_context* ctx, - struct page *page, unsigned int offset, unsigned int bytes) +static struct nfs_page *nfs_try_to_update_request(struct inode *inode, + struct page *page, + unsigned int offset, + unsigned int bytes) { - struct address_space *mapping = page->mapping; - struct inode *inode = mapping->host; - struct nfs_page *req, *new = NULL; - pgoff_t rqend, end; + struct nfs_page *req; + unsigned int rqend; + unsigned int end; + int error; + + if (!PagePrivate(page)) + return NULL; end = offset + bytes; + spin_lock(&inode->i_lock); for (;;) { - /* Loop over all inode entries and see if we find - * A request for the page we wish to update - */ - spin_lock(&inode->i_lock); req = nfs_page_find_request_locked(page); - if (req) { - if (!nfs_set_page_tag_locked(req)) { - int error; - - spin_unlock(&inode->i_lock); - error = nfs_wait_on_request(req); - nfs_release_request(req); - if (error < 0) { - if (new) { - radix_tree_preload_end(); - nfs_release_request(new); - } - return ERR_PTR(error); - } - continue; - } - spin_unlock(&inode->i_lock); - if (new) { - radix_tree_preload_end(); - nfs_release_request(new); - } + if (req == NULL) + goto out_unlock; + + rqend = req->wb_offset + req->wb_bytes; + /* + * Tell the caller to flush out the request if + * the offsets are non-contiguous. + * Note: nfs_flush_incompatible() will already + * have flushed out requests having wrong owners. + */ + if (!nfs_dirty_request(req) + || offset > rqend + || end < req->wb_offset) + goto out_flushme; + + if (nfs_set_page_tag_locked(req)) break; - } - if (new) { - nfs_lock_request_dontget(new); - nfs_inode_add_request(inode, new); - spin_unlock(&inode->i_lock); - radix_tree_preload_end(); - req = new; - goto out; - } + /* The request is locked, so wait and then retry */ spin_unlock(&inode->i_lock); - - new = nfs_create_request(ctx, inode, page, offset, bytes); - if (IS_ERR(new)) - return new; - if (radix_tree_preload(GFP_NOFS)) { - nfs_release_request(new); - return ERR_PTR(-ENOMEM); - } - } - - /* We have a request for our page. - * If the creds don't match, or the - * page addresses don't match, - * tell the caller to wait on the conflicting - * request. - */ - rqend = req->wb_offset + req->wb_bytes; - if (req->wb_context != ctx - || req->wb_page != page - || !nfs_dirty_request(req) - || offset > rqend || end < req->wb_offset) { - nfs_clear_page_tag_locked(req); - return ERR_PTR(-EBUSY); + error = nfs_wait_on_request(req); + nfs_release_request(req); + if (error != 0) + goto out_err; + spin_lock(&inode->i_lock); } /* Okay, the request matches. Update the region */ if (offset < req->wb_offset) { req->wb_offset = offset; req->wb_pgbase = offset; - req->wb_bytes = max(end, rqend) - req->wb_offset; - goto out; } - if (end > rqend) req->wb_bytes = end - req->wb_offset; + else + req->wb_bytes = rqend - req->wb_offset; +out_unlock: + spin_unlock(&inode->i_lock); + return req; +out_flushme: + spin_unlock(&inode->i_lock); + nfs_release_request(req); + error = nfs_wb_page(inode, page); +out_err: + return ERR_PTR(error); +} +/* + * Try to update an existing write request, or create one if there is none. + * + * Note: Should always be called with the Page Lock held to prevent races + * if we have to add a new request. Also assumes that the caller has + * already called nfs_flush_incompatible() if necessary. + */ +static struct nfs_page * nfs_setup_write_request(struct nfs_open_context* ctx, + struct page *page, unsigned int offset, unsigned int bytes) +{ + struct inode *inode = page->mapping->host; + struct nfs_page *req; + int error; + + req = nfs_try_to_update_request(inode, page, offset, bytes); + if (req != NULL) + goto out; + req = nfs_create_request(ctx, inode, page, offset, bytes); + if (IS_ERR(req)) + goto out; + error = nfs_inode_add_request(inode, req); + if (error != 0) { + nfs_release_request(req); + req = ERR_PTR(error); + } out: return req; } +static int nfs_writepage_setup(struct nfs_open_context *ctx, struct page *page, + unsigned int offset, unsigned int count) +{ + struct nfs_page *req; + + req = nfs_setup_write_request(ctx, page, offset, count); + if (IS_ERR(req)) + return PTR_ERR(req); + /* Update file length */ + nfs_grow_file(page, offset, count); + nfs_mark_uptodate(page, req->wb_pgbase, req->wb_bytes); + nfs_clear_page_tag_locked(req); + return 0; +} + int nfs_flush_incompatible(struct file *file, struct page *page) { struct nfs_open_context *ctx = nfs_file_open_context(file); |
