Btrfs: verify csums on read

Signed-off-by: Chris Mason <chris.mason@oracle.com>

6 files changed, 279 insertions, 60 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 48c611948d11..1eb333e2e18b 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -109,14 +109,14 @@ static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
                 return 1;
         if (k1.objectid < k2->objectid)
                 return -1;
-        if (k1.flags > k2->flags)
-                return 1;
-        if (k1.flags < k2->flags)
-                return -1;
         if (k1.offset > k2->offset)
                 return 1;
         if (k1.offset < k2->offset)
                 return -1;
+        if (k1.flags > k2->flags)
+                return 1;
+        if (k1.flags < k2->flags)
+                return -1;
         return 0;
 }
 
@@ -1165,7 +1165,6 @@ int btrfs_insert_empty_item(struct btrfs_trans_handle *trans, struct btrfs_root
                 BUG();
         ret = btrfs_search_slot(trans, root, cpu_key, path, data_size, 1);
         if (ret == 0) {
-                btrfs_release_path(root, path);
                 return -EEXIST;
         }
         if (ret < 0)
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 6ff87f44c5d8..df1a025a771c 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -21,6 +21,9 @@ struct btrfs_transaction;
  */
 #define BTRFS_NAME_LEN 255
 
+/* 32 bytes in various csum fields */
+#define BTRFS_CSUM_SIZE 32
+
 /*
  * the key defines the order in the tree, and so it also defines (optimal)
  * block layout.  objectid corresonds to the inode number.  The flags
@@ -37,21 +40,21 @@ struct btrfs_transaction;
  */
 struct btrfs_disk_key {
         __le64 objectid;
-        __le32 flags;
         __le64 offset;
+        __le32 flags;
 } __attribute__ ((__packed__));
 
 struct btrfs_key {
         u64 objectid;
-        u32 flags;
         u64 offset;
+        u32 flags;
 } __attribute__ ((__packed__));
 
 /*
  * every tree block (leaf or node) starts with this header.
  */
 struct btrfs_header {
-        __le32 csum[8];
+        u8 csum[BTRFS_CSUM_SIZE];
         u8 fsid[16]; /* FS specific uuid */
         __le64 blocknr; /* which block this node is supposed to live in */
         __le64 generation;
@@ -75,7 +78,7 @@ struct buffer_head;
  * it currently lacks any block count etc etc
  */
 struct btrfs_super_block {
-        __le32 csum[8];
+        u8 csum[BTRFS_CSUM_SIZE];
         /* the first 3 fields must match struct btrfs_header */
         u8 fsid[16];    /* FS specific uuid */
         __le64 blocknr; /* this block number */
@@ -147,7 +150,7 @@ struct btrfs_extent_item {
 } __attribute__ ((__packed__));
 
 struct btrfs_inode_timespec {
-        __le32 sec;
+        __le64 sec;
         __le32 nsec;
 } __attribute__ ((__packed__));
 
@@ -214,6 +217,10 @@ struct btrfs_file_extent_item {
         __le64 num_blocks;
 } __attribute__ ((__packed__));
 
+struct btrfs_csum_item {
+        u8 csum[BTRFS_CSUM_SIZE];
+} __attribute__ ((__packed__));
+
 struct btrfs_inode_map_item {
         struct btrfs_disk_key key;
 } __attribute__ ((__packed__));
@@ -284,26 +291,31 @@ struct btrfs_root {
  */
 #define BTRFS_EXTENT_DATA_KEY   4
 /*
+ * csum items have the checksums for data in the extents
+ */
+#define BTRFS_CSUM_ITEM_KEY     5
+
+/*
  * root items point to tree roots.  There are typically in the root
  * tree used by the super block to find all the other trees
  */
-#define BTRFS_ROOT_ITEM_KEY     5
+#define BTRFS_ROOT_ITEM_KEY     6
 /*
  * extent items are in the extent map tree.  These record which blocks
  * are used, and how many references there are to each block
  */
-#define BTRFS_EXTENT_ITEM_KEY   6
+#define BTRFS_EXTENT_ITEM_KEY   7
 
 /*
  * the inode map records which inode numbers are in use and where
  * they actually live on disk
  */
-#define BTRFS_INODE_MAP_ITEM_KEY 7
+#define BTRFS_INODE_MAP_ITEM_KEY 8
 /*
  * string items are for debugging.  They just store a short string of
  * data in the FS
  */
-#define BTRFS_STRING_ITEM_KEY   8
+#define BTRFS_STRING_ITEM_KEY   9
 
 static inline u64 btrfs_inode_generation(struct btrfs_inode_item *i)
 {
@@ -407,15 +419,15 @@ static inline void btrfs_set_inode_compat_flags(struct btrfs_inode_item *i,
         i->compat_flags = cpu_to_le16(val);
 }
 
-static inline u32 btrfs_timespec_sec(struct btrfs_inode_timespec *ts)
+static inline u64 btrfs_timespec_sec(struct btrfs_inode_timespec *ts)
 {
-        return le32_to_cpu(ts->sec);
+        return le64_to_cpu(ts->sec);
 }
 
 static inline void btrfs_set_timespec_sec(struct btrfs_inode_timespec *ts,
-                                          u32 val)
+                                          u64 val)
 {
-        ts->sec = cpu_to_le32(val);
+        ts->sec = cpu_to_le64(val);
 }
 
 static inline u32 btrfs_timespec_nsec(struct btrfs_inode_timespec *ts)
@@ -429,8 +441,6 @@ static inline void btrfs_set_timespec_nsec(struct btrfs_inode_timespec *ts,
         ts->nsec = cpu_to_le32(val);
 }
 
-
-
 static inline u64 btrfs_extent_owner(struct btrfs_extent_item *ei)
 {
         return le64_to_cpu(ei->owner);
@@ -905,4 +915,11 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
                              struct btrfs_root *root,
                              struct btrfs_path *path, u64 objectid,
                              u64 blocknr, int mod);
+int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
+                          struct btrfs_root *root,
+                          u64 objectid, u64 offset,
+                          char *data, size_t len);
+int btrfs_csum_verify_file_block(struct btrfs_root *root,
+                                 u64 objectid, u64 offset,
+                                 char *data, size_t len);
 #endif
diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
index f2c1dd40c087..f5db2b936502 100644
--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -127,31 +127,46 @@ static int btree_get_block(struct inode *inode, sector_t iblock,
         return 0;
 }
 
-static int csum_tree_block(struct btrfs_root * root, struct buffer_head *bh,
-                            int verify)
+int btrfs_csum_data(struct btrfs_root * root, char *data, size_t len,
+                    char *result)
 {
-        struct btrfs_node *node = btrfs_buffer_node(bh);
         struct scatterlist sg;
         struct crypto_hash *tfm = root->fs_info->hash_tfm;
         struct hash_desc desc;
         int ret;
-        char result[32];
 
         desc.tfm = tfm;
         desc.flags = 0;
-        sg_init_one(&sg, bh->b_data + 32, bh->b_size - 32);
+        sg_init_one(&sg, data, len);
         spin_lock(&root->fs_info->hash_lock);
-        ret = crypto_hash_digest(&desc, &sg, bh->b_size - 32, result);
+        ret = crypto_hash_digest(&desc, &sg, len, result);
         spin_unlock(&root->fs_info->hash_lock);
         if (ret) {
                 printk("sha256 digest failed\n");
         }
+        return ret;
+}
+static int csum_tree_block(struct btrfs_root *root, struct buffer_head *bh,
+                           int verify)
+{
+        char result[BTRFS_CSUM_SIZE];
+        int ret;
+        struct btrfs_node *node;
+
+        ret = btrfs_csum_data(root, bh->b_data + BTRFS_CSUM_SIZE,
+                              bh->b_size - BTRFS_CSUM_SIZE, result);
+        if (ret)
+                return ret;
         if (verify) {
-                if (memcmp(node->header.csum, result, sizeof(result)))
-                        printk("csum verify failed on %Lu\n", bh->b_blocknr);
-                return -EINVAL;
-        } else
-                memcpy(node->header.csum, result, sizeof(node->header.csum));
+                if (memcmp(bh->b_data, result, BTRFS_CSUM_SIZE)) {
+                        printk("checksum verify failed on %lu\n",
+                               bh->b_blocknr);
+                        return 1;
+                }
+        } else {
+                node = btrfs_buffer_node(bh);
+                memcpy(&node->header.csum, result, BTRFS_CSUM_SIZE);
+        }
         return 0;
 }
 
diff --git a/fs/btrfs/disk-io.h b/fs/btrfs/disk-io.h
index c2c38bda704d..f6998e2192ce 100644
--- a/fs/btrfs/disk-io.h
+++ b/fs/btrfs/disk-io.h
@@ -39,4 +39,6 @@ void btrfs_block_release(struct btrfs_root *root, struct buffer_head *buf);
 int write_ctree_super(struct btrfs_trans_handle *trans,
                       struct btrfs_root *root);
 struct buffer_head *btrfs_find_tree_block(struct btrfs_root *root, u64 blocknr);
+int btrfs_csum_data(struct btrfs_root * root, char *data, size_t len,
+                    char *result);
 #endif
diff --git a/fs/btrfs/file-item.c b/fs/btrfs/file-item.c
index 5230a44cb19b..2d2c23ca7cbf 100644
--- a/fs/btrfs/file-item.c
+++ b/fs/btrfs/file-item.c
@@ -57,3 +57,63 @@ int btrfs_lookup_file_extent(struct btrfs_trans_handle *trans,
         ret = btrfs_search_slot(trans, root, &file_key, path, ins_len, cow);
         return ret;
 }
+
+int btrfs_csum_file_block(struct btrfs_trans_handle *trans,
+                          struct btrfs_root *root,
+                          u64 objectid, u64 offset,
+                          char *data, size_t len)
+{
+        int ret;
+        struct btrfs_key file_key;
+        struct btrfs_path path;
+        struct btrfs_csum_item *item;
+
+        btrfs_init_path(&path);
+        file_key.objectid = objectid;
+        file_key.offset = offset;
+        file_key.flags = 0;
+        btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+        ret = btrfs_insert_empty_item(trans, root, &path, &file_key,
+                                      BTRFS_CSUM_SIZE);
+        if (ret != 0 && ret != -EEXIST)
+                goto fail;
+        item = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]), path.slots[0],
+                              struct btrfs_csum_item);
+        ret = 0;
+        ret = btrfs_csum_data(root, data, len, item->csum);
+        mark_buffer_dirty(path.nodes[0]);
+fail:
+        btrfs_release_path(root, &path);
+        return ret;
+}
+
+int btrfs_csum_verify_file_block(struct btrfs_root *root,
+                                 u64 objectid, u64 offset,
+                                 char *data, size_t len)
+{
+        int ret;
+        struct btrfs_key file_key;
+        struct btrfs_path path;
+        struct btrfs_csum_item *item;
+        char result[BTRFS_CSUM_SIZE];
+
+        btrfs_init_path(&path);
+        file_key.objectid = objectid;
+        file_key.offset = offset;
+        file_key.flags = 0;
+        btrfs_set_key_type(&file_key, BTRFS_CSUM_ITEM_KEY);
+        ret = btrfs_search_slot(NULL, root, &file_key, &path, 0, 0);
+        if (ret)
+                goto fail;
+        item = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]), path.slots[0],
+                              struct btrfs_csum_item);
+        ret = 0;
+        ret = btrfs_csum_data(root, data, len, result);
+        WARN_ON(ret);
+        if (memcmp(result, item->csum, BTRFS_CSUM_SIZE))
+                ret = 1;
+fail:
+        btrfs_release_path(root, &path);
+        return ret;
+}
+
diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index 7914b31f5bcd..04428137d75f 100644
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -249,15 +249,16 @@ static int btrfs_truncate_in_trans(struct btrfs_trans_handle *trans,
         struct btrfs_key key;
         struct btrfs_disk_key *found_key;
         struct btrfs_leaf *leaf;
-        struct btrfs_file_extent_item *fi;
-        u64 extent_start;
-        u64 extent_num_blocks;
+        struct btrfs_file_extent_item *fi = NULL;
+        u64 extent_start = 0;
+        u64 extent_num_blocks = 0;
+        int found_extent;
 
         /* FIXME, add redo link to tree so we don't leak on crash */
         key.objectid = inode->i_ino;
         key.offset = (u64)-1;
         key.flags = 0;
-        btrfs_set_key_type(&key, BTRFS_EXTENT_DATA_KEY);
+        btrfs_set_key_type(&key, BTRFS_CSUM_ITEM_KEY);
         while(1) {
                 btrfs_init_path(&path);
                 ret = btrfs_search_slot(trans, root, &key, &path, -1, 1);
@@ -273,25 +274,32 @@ static int btrfs_truncate_in_trans(struct btrfs_trans_handle *trans,
                 found_key = &leaf->items[path.slots[0]].key;
                 if (btrfs_disk_key_objectid(found_key) != inode->i_ino)
                         break;
-                if (btrfs_disk_key_type(found_key) != BTRFS_EXTENT_DATA_KEY)
+                if (btrfs_disk_key_type(found_key) != BTRFS_CSUM_ITEM_KEY &&
+                    btrfs_disk_key_type(found_key) != BTRFS_EXTENT_DATA_KEY)
                         break;
                 if (btrfs_disk_key_offset(found_key) < inode->i_size)
                         break;
-                fi = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]),
-                                    path.slots[0],
-                                    struct btrfs_file_extent_item);
-                extent_start = btrfs_file_extent_disk_blocknr(fi);
-                extent_num_blocks = btrfs_file_extent_disk_num_blocks(fi);
-                key.offset = btrfs_disk_key_offset(found_key) - 1;
+                if (btrfs_disk_key_type(found_key) == BTRFS_EXTENT_DATA_KEY) {
+                        fi = btrfs_item_ptr(btrfs_buffer_leaf(path.nodes[0]),
+                                            path.slots[0],
+                                            struct btrfs_file_extent_item);
+                        extent_start = btrfs_file_extent_disk_blocknr(fi);
+                        extent_num_blocks =
+                                btrfs_file_extent_disk_num_blocks(fi);
+                        inode->i_blocks -=
+                                btrfs_file_extent_num_blocks(fi) >> 9;
+                        found_extent = 1;
+                } else {
+                        found_extent = 0;
+                }
                 ret = btrfs_del_item(trans, root, &path);
                 BUG_ON(ret);
-                inode->i_blocks -= btrfs_file_extent_num_blocks(fi) >> 9;
                 btrfs_release_path(root, &path);
-                ret = btrfs_free_extent(trans, root, extent_start,
-                                        extent_num_blocks, 0);
-                BUG_ON(ret);
-                if (key.offset + 1 == 0)
-                        break;
+                if (found_extent) {
+                        ret = btrfs_free_extent(trans, root, extent_start,
+                                                extent_num_blocks, 0);
+                        BUG_ON(ret);
+                }
         }
         btrfs_release_path(root, &path);
         ret = 0;
@@ -975,10 +983,24 @@ static int dirty_and_release_pages(struct btrfs_trans_handle *trans,
         int err = 0;
         int ret;
         int this_write;
+        struct inode *inode = file->f_path.dentry->d_inode;
 
         for (i = 0; i < num_pages; i++) {
                 offset = pos & (PAGE_CACHE_SIZE -1);
                 this_write = min(PAGE_CACHE_SIZE - offset, write_bytes);
+                /* FIXME, one block at a time */
+
+                mutex_lock(&root->fs_info->fs_mutex);
+                trans = btrfs_start_transaction(root, 1);
+                btrfs_csum_file_block(trans, root, inode->i_ino,
+                                      pages[i]->index << PAGE_CACHE_SHIFT,
+                                      kmap(pages[i]), PAGE_CACHE_SIZE);
+                kunmap(pages[i]);
+                SetPageChecked(pages[i]);
+                ret = btrfs_end_transaction(trans, root);
+                BUG_ON(ret);
+                mutex_unlock(&root->fs_info->fs_mutex);
+
                 ret = nobh_commit_write(file, pages[i], offset,
                                          offset + this_write);
                 pos += this_write;
@@ -1022,7 +1044,7 @@ static int prepare_pages(struct btrfs_trans_handle *trans,
                 this_write = min(PAGE_CACHE_SIZE - offset, write_bytes);
                 ret = nobh_prepare_write(pages[i], offset,
                                          offset + this_write,
-                                         btrfs_get_block_lock);
+                                         btrfs_get_block);
                 pos += this_write;
                 if (ret) {
                         err = ret;
@@ -1051,7 +1073,6 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
         size_t num_written = 0;
         int err = 0;
         int ret = 0;
-        struct btrfs_trans_handle *trans;
         struct inode *inode = file->f_path.dentry->d_inode;
         struct btrfs_root *root = btrfs_sb(inode->i_sb);
         struct page *pages[1];
@@ -1077,25 +1098,18 @@ static ssize_t btrfs_file_write(struct file *file, const char __user *buf,
                 size_t write_bytes = min(count, PAGE_CACHE_SIZE - offset);
                 size_t num_pages = (write_bytes + PAGE_CACHE_SIZE - 1) >>
                                         PAGE_CACHE_SHIFT;
-                mutex_lock(&root->fs_info->fs_mutex);
-                trans = btrfs_start_transaction(root, 1);
-
-                ret = prepare_pages(trans, root, file, pages, num_pages,
+                ret = prepare_pages(NULL, root, file, pages, num_pages,
                                     pos, write_bytes);
                 BUG_ON(ret);
                 ret = btrfs_copy_from_user(pos, num_pages,
                                            write_bytes, pages, buf);
                 BUG_ON(ret);
 
-                mutex_unlock(&root->fs_info->fs_mutex);
-
-                ret = dirty_and_release_pages(trans, root, file, pages,
+                ret = dirty_and_release_pages(NULL, root, file, pages,
                                               num_pages, pos, write_bytes);
                 BUG_ON(ret);
                 btrfs_drop_pages(pages, num_pages);
 
-                ret = btrfs_end_transaction(trans, root);
-
                 buf += write_bytes;
                 count -= write_bytes;
                 pos += write_bytes;
@@ -1111,6 +1125,118 @@ out:
         return num_written ? num_written : err;
 }
 
+static int btrfs_read_actor(read_descriptor_t *desc, struct page *page,
+                        unsigned long offset, unsigned long size)
+{
+        char *kaddr;
+        unsigned long left, count = desc->count;
+
+        if (size > count)
+                size = count;
+
+        if (!PageChecked(page)) {
+                /* FIXME, do it per block */
+                struct btrfs_root *root = btrfs_sb(page->mapping->host->i_sb);
+                int ret = btrfs_csum_verify_file_block(root,
+                                          page->mapping->host->i_ino,
+                                          page->index << PAGE_CACHE_SHIFT,
+                                          kmap(page), PAGE_CACHE_SIZE);
+                if (ret) {
+                        printk("failed to verify ino %lu page %lu\n",
+                               page->mapping->host->i_ino,
+                               page->index);
+                        memset(page_address(page), 0, PAGE_CACHE_SIZE);
+                }
+                SetPageChecked(page);
+                kunmap(page);
+        }
+        /*
+         * Faults on the destination of a read are common, so do it before
+         * taking the kmap.
+         */
+        if (!fault_in_pages_writeable(desc->arg.buf, size)) {
+                kaddr = kmap_atomic(page, KM_USER0);
+                left = __copy_to_user_inatomic(desc->arg.buf,
+                                                kaddr + offset, size);
+                kunmap_atomic(kaddr, KM_USER0);
+                if (left == 0)
+                        goto success;
+        }
+
+        /* Do it the slow way */
+        kaddr = kmap(page);
+        left = __copy_to_user(desc->arg.buf, kaddr + offset, size);
+        kunmap(page);
+
+        if (left) {
+                size -= left;
+                desc->error = -EFAULT;
+        }
+success:
+        desc->count = count - size;
+        desc->written += size;
+        desc->arg.buf += size;
+        return size;
+}
+
+/**
+ * btrfs_file_aio_read - filesystem read routine
+ * @iocb:       kernel I/O control block
+ * @iov:        io vector request
+ * @nr_segs:    number of segments in the iovec
+ * @pos:        current file position
+ */
+static ssize_t btrfs_file_aio_read(struct kiocb *iocb, const struct iovec *iov,
+                                   unsigned long nr_segs, loff_t pos)
+{
+        struct file *filp = iocb->ki_filp;
+        ssize_t retval;
+        unsigned long seg;
+        size_t count;
+        loff_t *ppos = &iocb->ki_pos;
+
+        count = 0;
+        for (seg = 0; seg < nr_segs; seg++) {
+                const struct iovec *iv = &iov[seg];
+
+                /*
+                 * If any segment has a negative length, or the cumulative
+                 * length ever wraps negative then return -EINVAL.
+                 */
+                count += iv->iov_len;
+                if (unlikely((ssize_t)(count|iv->iov_len) < 0))
+                        return -EINVAL;
+                if (access_ok(VERIFY_WRITE, iv->iov_base, iv->iov_len))
+                        continue;
+                if (seg == 0)
+                        return -EFAULT;
+                nr_segs = seg;
+                count -= iv->iov_len;   /* This segment is no good */
+                break;
+        }
+        retval = 0;
+        if (count) {
+                for (seg = 0; seg < nr_segs; seg++) {
+                        read_descriptor_t desc;
+
+                        desc.written = 0;
+                        desc.arg.buf = iov[seg].iov_base;
+                        desc.count = iov[seg].iov_len;
+                        if (desc.count == 0)
+                                continue;
+                        desc.error = 0;
+                        do_generic_file_read(filp, ppos, &desc,
+                                             btrfs_read_actor);
+                        retval += desc.written;
+                        if (desc.error) {
+                                retval = retval ?: desc.error;
+                                break;
+                        }
+                }
+        }
+        return retval;
+}
+
 static int btrfs_get_sb(struct file_system_type *fs_type,
         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 {
@@ -1166,7 +1292,7 @@ static struct inode_operations btrfs_file_inode_operations = {
 static struct file_operations btrfs_file_operations = {
         .llseek         = generic_file_llseek,
         .read           = do_sync_read,
-        .aio_read       = generic_file_aio_read,
+        .aio_read       = btrfs_file_aio_read,
         .write          = btrfs_file_write,
         .mmap           = generic_file_mmap,
         .open           = generic_file_open,