nilfs2: fiemap support

This adds fiemap to nilfs.  Two new functions, nilfs_fiemap and
nilfs_find_uncommitted_extent are added.

nilfs_fiemap() implements the fiemap inode operation, and
nilfs_find_uncommitted_extent() helps to get a range of data blocks
whose physical location has not been determined.

nilfs_fiemap() collects extent information by looping through
nilfs_bmap_lookup_contig and nilfs_find_uncommitted_extent routines.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

6 files changed, 222 insertions, 0 deletions

diff --git a/fs/nilfs2/file.c b/fs/nilfs2/file.c
index c9a30d7ff6f..2f560c9fb80 100644
--- a/fs/nilfs2/file.c
+++ b/fs/nilfs2/file.c
@@ -155,6 +155,7 @@ const struct inode_operations nilfs_file_inode_operations = {
         .truncate       = nilfs_truncate,
         .setattr        = nilfs_setattr,
         .permission     = nilfs_permission,
+        .fiemap         = nilfs_fiemap,
 };
 
 /* end of file */
diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
index 1a546a86d7a..b2a815033ee 100644
--- a/fs/nilfs2/inode.c
+++ b/fs/nilfs2/inode.c
@@ -916,3 +916,134 @@ void nilfs_dirty_inode(struct inode *inode)
         nilfs_mark_inode_dirty(inode);
         nilfs_transaction_commit(inode->i_sb); /* never fails */
 }
+
+int nilfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
+                 __u64 start, __u64 len)
+{
+        struct the_nilfs *nilfs = NILFS_I_NILFS(inode);
+        __u64 logical = 0, phys = 0, size = 0;
+        __u32 flags = 0;
+        loff_t isize;
+        sector_t blkoff, end_blkoff;
+        sector_t delalloc_blkoff;
+        unsigned long delalloc_blklen;
+        unsigned int blkbits = inode->i_blkbits;
+        int ret, n;
+
+        ret = fiemap_check_flags(fieinfo, FIEMAP_FLAG_SYNC);
+        if (ret)
+                return ret;
+
+        mutex_lock(&inode->i_mutex);
+
+        isize = i_size_read(inode);
+
+        blkoff = start >> blkbits;
+        end_blkoff = (start + len - 1) >> blkbits;
+
+        delalloc_blklen = nilfs_find_uncommitted_extent(inode, blkoff,
+                                                        &delalloc_blkoff);
+
+        do {
+                __u64 blkphy;
+                unsigned int maxblocks;
+
+                if (delalloc_blklen && blkoff == delalloc_blkoff) {
+                        if (size) {
+                                /* End of the current extent */
+                                ret = fiemap_fill_next_extent(
+                                        fieinfo, logical, phys, size, flags);
+                                if (ret)
+                                        break;
+                        }
+                        if (blkoff > end_blkoff)
+                                break;
+
+                        flags = FIEMAP_EXTENT_MERGED | FIEMAP_EXTENT_DELALLOC;
+                        logical = blkoff << blkbits;
+                        phys = 0;
+                        size = delalloc_blklen << blkbits;
+
+                        blkoff = delalloc_blkoff + delalloc_blklen;
+                        delalloc_blklen = nilfs_find_uncommitted_extent(
+                                inode, blkoff, &delalloc_blkoff);
+                        continue;
+                }
+
+                /*
+                 * Limit the number of blocks that we look up so as
+                 * not to get into the next delayed allocation extent.
+                 */
+                maxblocks = INT_MAX;
+                if (delalloc_blklen)
+                        maxblocks = min_t(sector_t, delalloc_blkoff - blkoff,
+                                          maxblocks);
+                blkphy = 0;
+
+                down_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
+                n = nilfs_bmap_lookup_contig(
+                        NILFS_I(inode)->i_bmap, blkoff, &blkphy, maxblocks);
+                up_read(&NILFS_MDT(nilfs->ns_dat)->mi_sem);
+
+                if (n < 0) {
+                        int past_eof;
+
+                        if (unlikely(n != -ENOENT))
+                                break; /* error */
+
+                        /* HOLE */
+                        blkoff++;
+                        past_eof = ((blkoff << blkbits) >= isize);
+
+                        if (size) {
+                                /* End of the current extent */
+
+                                if (past_eof)
+                                        flags |= FIEMAP_EXTENT_LAST;
+
+                                ret = fiemap_fill_next_extent(
+                                        fieinfo, logical, phys, size, flags);
+                                if (ret)
+                                        break;
+                                size = 0;
+                        }
+                        if (blkoff > end_blkoff || past_eof)
+                                break;
+                } else {
+                        if (size) {
+                                if (phys && blkphy << blkbits == phys + size) {
+                                        /* The current extent goes on */
+                                        size += n << blkbits;
+                                } else {
+                                        /* Terminate the current extent */
+                                        ret = fiemap_fill_next_extent(
+                                                fieinfo, logical, phys, size,
+                                                flags);
+                                        if (ret || blkoff > end_blkoff)
+                                                break;
+
+                                        /* Start another extent */
+                                        flags = FIEMAP_EXTENT_MERGED;
+                                        logical = blkoff << blkbits;
+                                        phys = blkphy << blkbits;
+                                        size = n << blkbits;
+                                }
+                        } else {
+                                /* Start a new extent */
+                                flags = FIEMAP_EXTENT_MERGED;
+                                logical = blkoff << blkbits;
+                                phys = blkphy << blkbits;
+                                size = n << blkbits;
+                        }
+                        blkoff += n;
+                }
+                cond_resched();
+        } while (true);
+
+        /* If ret is 1 then we just hit the end of the extent array */
+        if (ret == 1)
+                ret = 0;
+
+        mutex_unlock(&inode->i_mutex);
+        return ret;
+}
diff --git a/fs/nilfs2/namei.c b/fs/nilfs2/namei.c
index 6e9557ecf16..98034271cd0 100644
--- a/fs/nilfs2/namei.c
+++ b/fs/nilfs2/namei.c
@@ -577,6 +577,7 @@ const struct inode_operations nilfs_dir_inode_operations = {
         .rename         = nilfs_rename,
         .setattr        = nilfs_setattr,
         .permission     = nilfs_permission,
+        .fiemap         = nilfs_fiemap,
 };
 
 const struct inode_operations nilfs_special_inode_operations = {
diff --git a/fs/nilfs2/nilfs.h b/fs/nilfs2/nilfs.h
index 0ca98823db5..a0e21363e86 100644
--- a/fs/nilfs2/nilfs.h
+++ b/fs/nilfs2/nilfs.h
@@ -264,6 +264,8 @@ extern int nilfs_set_file_dirty(struct nilfs_sb_info *, struct inode *,
                                 unsigned);
 extern int nilfs_mark_inode_dirty(struct inode *);
 extern void nilfs_dirty_inode(struct inode *);
+int nilfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
+                 __u64 start, __u64 len);
 
 /* super.c */
 extern struct inode *nilfs_alloc_inode(struct super_block *);
diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c
index a6c3c2e817f..48a775ec1d2 100644
--- a/fs/nilfs2/page.c
+++ b/fs/nilfs2/page.c
@@ -546,3 +546,87 @@ int __nilfs_clear_page_dirty(struct page *page)
         }
         return TestClearPageDirty(page);
 }
+
+/**
+ * nilfs_find_uncommitted_extent - find extent of uncommitted data
+ * @inode: inode
+ * @start_blk: start block offset (in)
+ * @blkoff: start offset of the found extent (out)
+ *
+ * This function searches an extent of buffers marked "delayed" which
+ * starts from a block offset equal to or larger than @start_blk.  If
+ * such an extent was found, this will store the start offset in
+ * @blkoff and return its length in blocks.  Otherwise, zero is
+ * returned.
+ */
+unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
+                                            sector_t start_blk,
+                                            sector_t *blkoff)
+{
+        unsigned int i;
+        pgoff_t index;
+        unsigned int nblocks_in_page;
+        unsigned long length = 0;
+        sector_t b;
+        struct pagevec pvec;
+        struct page *page;
+
+        if (inode->i_mapping->nrpages == 0)
+                return 0;
+
+        index = start_blk >> (PAGE_CACHE_SHIFT - inode->i_blkbits);
+        nblocks_in_page = 1U << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+
+        pagevec_init(&pvec, 0);
+
+repeat:
+        pvec.nr = find_get_pages_contig(inode->i_mapping, index, PAGEVEC_SIZE,
+                                        pvec.pages);
+        if (pvec.nr == 0)
+                return length;
+
+        if (length > 0 && pvec.pages[0]->index > index)
+                goto out;
+
+        b = pvec.pages[0]->index << (PAGE_CACHE_SHIFT - inode->i_blkbits);
+        i = 0;
+        do {
+                page = pvec.pages[i];
+
+                lock_page(page);
+                if (page_has_buffers(page)) {
+                        struct buffer_head *bh, *head;
+
+                        bh = head = page_buffers(page);
+                        do {
+                                if (b < start_blk)
+                                        continue;
+                                if (buffer_delay(bh)) {
+                                        if (length == 0)
+                                                *blkoff = b;
+                                        length++;
+                                } else if (length > 0) {
+                                        goto out_locked;
+                                }
+                        } while (++b, bh = bh->b_this_page, bh != head);
+                } else {
+                        if (length > 0)
+                                goto out_locked;
+
+                        b += nblocks_in_page;
+                }
+                unlock_page(page);
+
+        } while (++i < pagevec_count(&pvec));
+
+        index = page->index + 1;
+        pagevec_release(&pvec);
+        cond_resched();
+        goto repeat;
+
+out_locked:
+        unlock_page(page);
+out:
+        pagevec_release(&pvec);
+        return length;
+}
diff --git a/fs/nilfs2/page.h b/fs/nilfs2/page.h
index fb9e8a8a203..622df27cd89 100644
--- a/fs/nilfs2/page.h
+++ b/fs/nilfs2/page.h
@@ -66,6 +66,9 @@ void nilfs_mapping_init(struct address_space *mapping,
                         struct backing_dev_info *bdi,
                         const struct address_space_operations *aops);
 unsigned nilfs_page_count_clean_buffers(struct page *, unsigned, unsigned);
+unsigned long nilfs_find_uncommitted_extent(struct inode *inode,
+                                            sector_t start_blk,
+                                            sector_t *blkoff);
 
 #define NILFS_PAGE_BUG(page, m, a...) \
         do { nilfs_page_bug(page); BUG(); } while (0)