From 9ac3d3e8460e3fa6f3a9a39c2049904005016db6 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 28 Apr 2016 19:52:56 -0400 Subject: [PATCH] nfs: switch to ->iterate_shared() aside of the usual care about seeding dcache from readdir, we need to be careful about the pagecache evictions here. Signed-off-by: Al Viro --- fs/nfs/dir.c | 71 +++++++++++++++++++++++++++++++--------------------- 1 file changed, 43 insertions(+), 28 deletions(-) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index 33eb81738d03..cd3c754e3f89 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -57,7 +57,7 @@ static void nfs_readdir_clear_array(struct page*); const struct file_operations nfs_dir_operations = { .llseek = nfs_llseek_dir, .read = generic_read_dir, - .iterate = nfs_readdir, + .iterate_shared = nfs_readdir, .open = nfs_opendir, .release = nfs_closedir, .fsync = nfs_fsync_dir, @@ -145,6 +145,7 @@ struct nfs_cache_array_entry { }; struct nfs_cache_array { + atomic_t refcount; int size; int eof_index; u64 last_cookie; @@ -200,11 +201,20 @@ void nfs_readdir_clear_array(struct page *page) int i; array = kmap_atomic(page); - for (i = 0; i < array->size; i++) - kfree(array->array[i].string.name); + if (atomic_dec_and_test(&array->refcount)) + for (i = 0; i < array->size; i++) + kfree(array->array[i].string.name); kunmap_atomic(array); } +static bool grab_page(struct page *page) +{ + struct nfs_cache_array *array = kmap_atomic(page); + bool res = atomic_inc_not_zero(&array->refcount); + kunmap_atomic(array); + return res; +} + /* * the caller is responsible for freeing qstr.name * when called by nfs_readdir_add_to_array, the strings will be freed in @@ -470,6 +480,7 @@ static void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry) { struct qstr filename = QSTR_INIT(entry->name, entry->len); + DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq); struct dentry *dentry; struct dentry *alias; struct inode *dir = d_inode(parent); @@ -489,7 +500,13 @@ void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry) filename.hash = full_name_hash(filename.name, filename.len); dentry = d_lookup(parent, &filename); - if (dentry != NULL) { +again: + if (!dentry) { + dentry = d_alloc_parallel(parent, &filename, &wq); + if (IS_ERR(dentry)) + return; + } + if (!d_in_lookup(dentry)) { /* Is there a mountpoint here? If so, just exit */ if (!nfs_fsid_equal(&NFS_SB(dentry->d_sb)->fsid, &entry->fattr->fsid)) @@ -503,26 +520,21 @@ void nfs_prime_dcache(struct dentry *parent, struct nfs_entry *entry) } else { d_invalidate(dentry); dput(dentry); + dentry = NULL; + goto again; } } - dentry = d_alloc(parent, &filename); - if (dentry == NULL) - return; - inode = nfs_fhget(dentry->d_sb, entry->fh, entry->fattr, entry->label); - if (IS_ERR(inode)) - goto out; - alias = d_splice_alias(inode, dentry); - if (IS_ERR(alias)) - goto out; - else if (alias) { - nfs_set_verifier(alias, nfs_save_change_attribute(dir)); - dput(alias); - } else - nfs_set_verifier(dentry, nfs_save_change_attribute(dir)); - + d_lookup_done(dentry); + if (alias) { + if (IS_ERR(alias)) + goto out; + dput(dentry); + dentry = alias; + } + nfs_set_verifier(dentry, nfs_save_change_attribute(dir)); out: dput(dentry); } @@ -643,6 +655,7 @@ int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page, goto out_label_free; } memset(array, 0, sizeof(struct nfs_cache_array)); + atomic_set(&array->refcount, 1); array->eof_index = -1; status = nfs_readdir_alloc_pages(pages, array_size); @@ -705,8 +718,7 @@ int nfs_readdir_filler(nfs_readdir_descriptor_t *desc, struct page* page) static void cache_page_release(nfs_readdir_descriptor_t *desc) { - if (!desc->page->mapping) - nfs_readdir_clear_array(desc->page); + nfs_readdir_clear_array(desc->page); put_page(desc->page); desc->page = NULL; } @@ -714,8 +726,16 @@ void cache_page_release(nfs_readdir_descriptor_t *desc) static struct page *get_cache_page(nfs_readdir_descriptor_t *desc) { - return read_cache_page(file_inode(desc->file)->i_mapping, + struct page *page; + + for (;;) { + page = read_cache_page(file_inode(desc->file)->i_mapping, desc->page_index, (filler_t *)nfs_readdir_filler, desc); + if (IS_ERR(page) || grab_page(page)) + break; + put_page(page); + } + return page; } /* @@ -934,13 +954,11 @@ static int nfs_readdir(struct file *file, struct dir_context *ctx) static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int whence) { - struct inode *inode = file_inode(filp); struct nfs_open_dir_context *dir_ctx = filp->private_data; dfprintk(FILE, "NFS: llseek dir(%pD2, %lld, %d)\n", filp, offset, whence); - inode_lock(inode); switch (whence) { case 1: offset += filp->f_pos; @@ -948,16 +966,13 @@ static loff_t nfs_llseek_dir(struct file *filp, loff_t offset, int whence) if (offset >= 0) break; default: - offset = -EINVAL; - goto out; + return -EINVAL; } if (offset != filp->f_pos) { filp->f_pos = offset; dir_ctx->dir_cookie = 0; dir_ctx->duped = 0; } -out: - inode_unlock(inode); return offset; }