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>

1 files changed, 131 insertions, 0 deletions

diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
index 1a546a86d7a7..b2a815033ee3 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;
+}