Btrfs: create a helper to create em for IO

We have similar codes to create and insert extent mapping around IO path,
this merges them into a single helper.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 175c28a..b37b062 100644 (file)
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -109,11 +109,11 @@ static noinline int cow_file_range(struct inode *inode,
                                   u64 start, u64 end, u64 delalloc_end,
                                   int *page_started, unsigned long *nr_written,
                                   int unlock, struct btrfs_dedupe_hash *hash);
-static struct extent_map *create_pinned_em(struct inode *inode, u64 start,
-                                          u64 len, u64 orig_start,
-                                          u64 block_start, u64 block_len,
-                                          u64 orig_block_len, u64 ram_bytes,
-                                          int type);
+static struct extent_map *create_io_em(struct inode *inode, u64 start, u64 len,
+                                      u64 orig_start, u64 block_start,
+                                      u64 block_len, u64 orig_block_len,
+                                      u64 ram_bytes, int compress_type,
+                                      int type);
 
 static int btrfs_dirty_inode(struct inode *inode);
 
@@ -697,7 +697,6 @@ static noinline void submit_compressed_extents(struct inode *inode,
        struct btrfs_key ins;
        struct extent_map *em;
        struct btrfs_root *root = BTRFS_I(inode)->root;
-       struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
        struct extent_io_tree *io_tree;
        int ret = 0;
 
@@ -785,46 +784,19 @@ retry:
                 * here we're doing allocation and writeback of the
                 * compressed pages
                 */
-               btrfs_drop_extent_cache(inode, async_extent->start,
-                                       async_extent->start +
-                                       async_extent->ram_size - 1, 0);
-
-               em = alloc_extent_map();
-               if (!em) {
-                       ret = -ENOMEM;
-                       goto out_free_reserve;
-               }
-               em->start = async_extent->start;
-               em->len = async_extent->ram_size;
-               em->orig_start = em->start;
-               em->mod_start = em->start;
-               em->mod_len = em->len;
-
-               em->block_start = ins.objectid;
-               em->block_len = ins.offset;
-               em->orig_block_len = ins.offset;
-               em->ram_bytes = async_extent->ram_size;
-               em->bdev = fs_info->fs_devices->latest_bdev;
-               em->compress_type = async_extent->compress_type;
-               set_bit(EXTENT_FLAG_PINNED, &em->flags);
-               set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
-               em->generation = -1;
-
-               while (1) {
-                       write_lock(&em_tree->lock);
-                       ret = add_extent_mapping(em_tree, em, 1);
-                       write_unlock(&em_tree->lock);
-                       if (ret != -EEXIST) {
-                               free_extent_map(em);
-                               break;
-                       }
-                       btrfs_drop_extent_cache(inode, async_extent->start,
-                                               async_extent->start +
-                                               async_extent->ram_size - 1, 0);
-               }
-
-               if (ret)
+               em = create_io_em(inode, async_extent->start,
+                                 async_extent->ram_size, /* len */
+                                 async_extent->start, /* orig_start */
+                                 ins.objectid, /* block_start */
+                                 ins.offset, /* block_len */
+                                 ins.offset, /* orig_block_len */
+                                 async_extent->ram_size, /* ram_bytes */
+                                 async_extent->compress_type,
+                                 BTRFS_ORDERED_COMPRESSED);
+               if (IS_ERR(em))
+                       /* ret value is not necessary due to void function */
                        goto out_free_reserve;
+               free_extent_map(em);
 
                ret = btrfs_add_ordered_extent_compress(inode,
                                                async_extent->start,
@@ -959,7 +931,6 @@ static noinline int cow_file_range(struct inode *inode,
        u64 blocksize = fs_info->sectorsize;
        struct btrfs_key ins;
        struct extent_map *em;
-       struct extent_map_tree *em_tree = &BTRFS_I(inode)->extent_tree;
        int ret = 0;
 
        if (btrfs_is_free_space_inode(inode)) {
@@ -1012,39 +983,18 @@ static noinline int cow_file_range(struct inode *inode,
                if (ret < 0)
                        goto out_unlock;
 
-               em = alloc_extent_map();
-               if (!em) {
-                       ret = -ENOMEM;
-                       goto out_reserve;
-               }
-               em->start = start;
-               em->orig_start = em->start;
                ram_size = ins.offset;
-               em->len = ins.offset;
-               em->mod_start = em->start;
-               em->mod_len = em->len;
-
-               em->block_start = ins.objectid;
-               em->block_len = ins.offset;
-               em->orig_block_len = ins.offset;
-               em->ram_bytes = ram_size;
-               em->bdev = fs_info->fs_devices->latest_bdev;
-               set_bit(EXTENT_FLAG_PINNED, &em->flags);
-               em->generation = -1;
-
-               while (1) {
-                       write_lock(&em_tree->lock);
-                       ret = add_extent_mapping(em_tree, em, 1);
-                       write_unlock(&em_tree->lock);
-                       if (ret != -EEXIST) {
-                               free_extent_map(em);
-                               break;
-                       }
-                       btrfs_drop_extent_cache(inode, start,
-                                               start + ram_size - 1, 0);
-               }
-               if (ret)
+               em = create_io_em(inode, start, ins.offset, /* len */
+                                 start, /* orig_start */
+                                 ins.objectid, /* block_start */
+                                 ins.offset, /* block_len */
+                                 ins.offset, /* orig_block_len */
+                                 ram_size, /* ram_bytes */
+                                 BTRFS_COMPRESS_NONE, /* compress_type */
+                                 0 /* type */);
+               if (IS_ERR(em))
                        goto out_reserve;
+               free_extent_map(em);
 
                cur_alloc_size = ins.offset;
                ret = btrfs_add_ordered_extent(inode, start, ins.objectid,
@@ -1251,6 +1201,7 @@ static noinline int run_delalloc_nocow(struct inode *inode,
        struct btrfs_path *path;
        struct btrfs_file_extent_item *fi;
        struct btrfs_key found_key;
+       struct extent_map *em;
        u64 cow_start;
        u64 cur_offset;
        u64 extent_end;
@@ -1431,35 +1382,28 @@ out_check:
                }
 
                if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
-                       struct extent_map *em;
-                       struct extent_map_tree *em_tree;
-                       em_tree = &BTRFS_I(inode)->extent_tree;
-                       em = alloc_extent_map();
-                       BUG_ON(!em); /* -ENOMEM */
-                       em->start = cur_offset;
-                       em->orig_start = found_key.offset - extent_offset;
-                       em->len = num_bytes;
-                       em->block_len = num_bytes;
-                       em->block_start = disk_bytenr;
-                       em->orig_block_len = disk_num_bytes;
-                       em->ram_bytes = ram_bytes;
-                       em->bdev = fs_info->fs_devices->latest_bdev;
-                       em->mod_start = em->start;
-                       em->mod_len = em->len;
-                       set_bit(EXTENT_FLAG_PINNED, &em->flags);
-                       set_bit(EXTENT_FLAG_FILLING, &em->flags);
-                       em->generation = -1;
-                       while (1) {
-                               write_lock(&em_tree->lock);
-                               ret = add_extent_mapping(em_tree, em, 1);
-                               write_unlock(&em_tree->lock);
-                               if (ret != -EEXIST) {
-                                       free_extent_map(em);
-                                       break;
-                               }
-                               btrfs_drop_extent_cache(inode, em->start,
-                                               em->start + em->len - 1, 0);
+                       u64 orig_start = found_key.offset - extent_offset;
+
+                       em = create_io_em(inode, cur_offset, num_bytes,
+                                         orig_start,
+                                         disk_bytenr, /* block_start */
+                                         num_bytes, /* block_len */
+                                         disk_num_bytes, /* orig_block_len */
+                                         ram_bytes, BTRFS_COMPRESS_NONE,
+                                         BTRFS_ORDERED_PREALLOC);
+                       if (IS_ERR(em)) {
+                               if (!nolock && nocow)
+                                       btrfs_end_write_no_snapshoting(root);
+                               if (nocow)
+                                       btrfs_dec_nocow_writers(fs_info,
+                                                               disk_bytenr);
+                               ret = PTR_ERR(em);
+                               goto error;
                        }
+                       free_extent_map(em);
+               }
+
+               if (extent_type == BTRFS_FILE_EXTENT_PREALLOC) {
                        type = BTRFS_ORDERED_PREALLOC;
                } else {
                        type = BTRFS_ORDERED_NOCOW;
@@ -7207,9 +7151,11 @@ static struct extent_map *btrfs_create_dio_extent(struct inode *inode,
        int ret;
 
        if (type != BTRFS_ORDERED_NOCOW) {
-               em = create_pinned_em(inode, start, len, orig_start,
-                                     block_start, block_len, orig_block_len,
-                                     ram_bytes, type);
+               em = create_io_em(inode, start, len, orig_start,
+                                 block_start, block_len, orig_block_len,
+                                 ram_bytes,
+                                 BTRFS_COMPRESS_NONE, /* compress_type */
+                                 type);
                if (IS_ERR(em))
                        goto out;
        }
@@ -7545,17 +7491,23 @@ static int lock_extent_direct(struct inode *inode, u64 lockstart, u64 lockend,
        return ret;
 }
 
-static struct extent_map *create_pinned_em(struct inode *inode, u64 start,
-                                          u64 len, u64 orig_start,
-                                          u64 block_start, u64 block_len,
-                                          u64 orig_block_len, u64 ram_bytes,
-                                          int type)
+/* The callers of this must take lock_extent() */
+static struct extent_map *create_io_em(struct inode *inode, u64 start, u64 len,
+                                      u64 orig_start, u64 block_start,
+                                      u64 block_len, u64 orig_block_len,
+                                      u64 ram_bytes, int compress_type,
+                                      int type)
 {
        struct extent_map_tree *em_tree;
        struct extent_map *em;
        struct btrfs_root *root = BTRFS_I(inode)->root;
        int ret;
 
+       ASSERT(type == BTRFS_ORDERED_PREALLOC ||
+              type == BTRFS_ORDERED_COMPRESSED ||
+              type == BTRFS_ORDERED_NOCOW ||
+              type == 0);
+
        em_tree = &BTRFS_I(inode)->extent_tree;
        em = alloc_extent_map();
        if (!em)
@@ -7563,8 +7515,6 @@ static struct extent_map *create_pinned_em(struct inode *inode, u64 start,
 
        em->start = start;
        em->orig_start = orig_start;
-       em->mod_start = start;
-       em->mod_len = len;
        em->len = len;
        em->block_len = block_len;
        em->block_start = block_start;
@@ -7575,6 +7525,10 @@ static struct extent_map *create_pinned_em(struct inode *inode, u64 start,
        set_bit(EXTENT_FLAG_PINNED, &em->flags);
        if (type == BTRFS_ORDERED_PREALLOC)
                set_bit(EXTENT_FLAG_FILLING, &em->flags);
+       else if (type == BTRFS_ORDERED_COMPRESSED) {
+               set_bit(EXTENT_FLAG_COMPRESSED, &em->flags);
+               em->compress_type = compress_type;
+       }
 
        do {
                btrfs_drop_extent_cache(inode, em->start,
@@ -7582,6 +7536,10 @@ static struct extent_map *create_pinned_em(struct inode *inode, u64 start,
                write_lock(&em_tree->lock);
                ret = add_extent_mapping(em_tree, em, 1);
                write_unlock(&em_tree->lock);
+               /*
+                * The caller has taken lock_extent(), who could race with us
+                * to add em?
+                */
        } while (ret == -EEXIST);
 
        if (ret) {
@@ -7589,6 +7547,7 @@ static struct extent_map *create_pinned_em(struct inode *inode, u64 start,
                return ERR_PTR(ret);
        }
 
+       /* em got 2 refs now, callers needs to do free_extent_map once. */
        return em;
 }