ocfs2: zero tail of sparse files on truncate

Since we don't zero on extend anymore, truncate needs to be fixed up to zero
the part of a file between i_size and and end of it's cluster. Otherwise a
subsequent extend could expose bad data.

This introduced a new helper, which can be used in ocfs2_write().

Signed-off-by: Mark Fasheh <mark.fasheh@oracle.com>

7 files changed, 328 insertions, 25 deletions

diff --git a/fs/ocfs2/alloc.c b/fs/ocfs2/alloc.c
index 9a40603c4d4b..98694a1add43 100644
--- a/fs/ocfs2/alloc.c
+++ b/fs/ocfs2/alloc.c
@@ -27,6 +27,7 @@
 #include <linux/types.h>
 #include <linux/slab.h>
 #include <linux/highmem.h>
+#include <linux/swap.h>
 
 #define MLOG_MASK_PREFIX ML_DISK_ALLOC
 #include <cluster/masklog.h>
@@ -34,6 +35,7 @@
 #include "ocfs2.h"
 
 #include "alloc.h"
+#include "aops.h"
 #include "dlmglue.h"
 #include "extent_map.h"
 #include "inode.h"
@@ -3342,6 +3344,228 @@ bail:
         return status;
 }
 
+static int ocfs2_writeback_zero_func(handle_t *handle, struct buffer_head *bh)
+{
+        set_buffer_uptodate(bh);
+        mark_buffer_dirty(bh);
+        return 0;
+}
+
+static int ocfs2_ordered_zero_func(handle_t *handle, struct buffer_head *bh)
+{
+        set_buffer_uptodate(bh);
+        mark_buffer_dirty(bh);
+        return ocfs2_journal_dirty_data(handle, bh);
+}
+
+static void ocfs2_zero_cluster_pages(struct inode *inode, loff_t isize,
+                                     struct page **pages, int numpages,
+                                     u64 phys, handle_t *handle)
+{
+        int i, ret, partial = 0;
+        void *kaddr;
+        struct page *page;
+        unsigned int from, to = PAGE_CACHE_SIZE;
+        struct super_block *sb = inode->i_sb;
+
+        BUG_ON(!ocfs2_sparse_alloc(OCFS2_SB(sb)));
+
+        if (numpages == 0)
+                goto out;
+
+        from = isize & (PAGE_CACHE_SIZE - 1); /* 1st page offset */
+        if (PAGE_CACHE_SHIFT > OCFS2_SB(sb)->s_clustersize_bits) {
+                /*
+                 * Since 'from' has been capped to a value below page
+                 * size, this calculation won't be able to overflow
+                 * 'to'
+                 */
+                to = ocfs2_align_bytes_to_clusters(sb, from);
+
+                /*
+                 * The truncate tail in this case should never contain
+                 * more than one page at maximum. The loop below also
+                 * assumes this.
+                 */
+                BUG_ON(numpages != 1);
+        }
+
+        for(i = 0; i < numpages; i++) {
+                page = pages[i];
+
+                BUG_ON(from > PAGE_CACHE_SIZE);
+                BUG_ON(to > PAGE_CACHE_SIZE);
+
+                ret = ocfs2_map_page_blocks(page, &phys, inode, from, to, 0);
+                if (ret)
+                        mlog_errno(ret);
+
+                kaddr = kmap_atomic(page, KM_USER0);
+                memset(kaddr + from, 0, to - from);
+                kunmap_atomic(kaddr, KM_USER0);
+
+                /*
+                 * Need to set the buffers we zero'd into uptodate
+                 * here if they aren't - ocfs2_map_page_blocks()
+                 * might've skipped some
+                 */
+                if (ocfs2_should_order_data(inode)) {
+                        ret = walk_page_buffers(handle,
+                                                page_buffers(page),
+                                                from, to, &partial,
+                                                ocfs2_ordered_zero_func);
+                        if (ret < 0)
+                                mlog_errno(ret);
+                } else {
+                        ret = walk_page_buffers(handle, page_buffers(page),
+                                                from, to, &partial,
+                                                ocfs2_writeback_zero_func);
+                        if (ret < 0)
+                                mlog_errno(ret);
+                }
+
+                if (!partial)
+                        SetPageUptodate(page);
+
+                flush_dcache_page(page);
+
+                /*
+                 * Every page after the 1st one should be completely zero'd.
+                 */
+                from = 0;
+        }
+out:
+        if (pages) {
+                for (i = 0; i < numpages; i++) {
+                        page = pages[i];
+                        unlock_page(page);
+                        mark_page_accessed(page);
+                        page_cache_release(page);
+                }
+        }
+}
+
+static int ocfs2_grab_eof_pages(struct inode *inode, loff_t isize, struct page **pages,
+                                int *num, u64 *phys)
+{
+        int i, numpages = 0, ret = 0;
+        unsigned int csize = OCFS2_SB(inode->i_sb)->s_clustersize;
+        struct super_block *sb = inode->i_sb;
+        struct address_space *mapping = inode->i_mapping;
+        unsigned long index;
+        u64 next_cluster_bytes;
+
+        BUG_ON(!ocfs2_sparse_alloc(OCFS2_SB(sb)));
+
+        /* Cluster boundary, so we don't need to grab any pages. */
+        if ((isize & (csize - 1)) == 0)
+                goto out;
+
+        ret = ocfs2_extent_map_get_blocks(inode, isize >> sb->s_blocksize_bits,
+                                          phys, NULL);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        /* Tail is a hole. */
+        if (*phys == 0)
+                goto out;
+
+        next_cluster_bytes = ocfs2_align_bytes_to_clusters(inode->i_sb, isize);
+        index = isize >> PAGE_CACHE_SHIFT;
+        do {
+                pages[numpages] = grab_cache_page(mapping, index);
+                if (!pages[numpages]) {
+                        ret = -ENOMEM;
+                        mlog_errno(ret);
+                        goto out;
+                }
+
+                numpages++;
+                index++;
+        } while (index < (next_cluster_bytes >> PAGE_CACHE_SHIFT));
+
+out:
+        if (ret != 0) {
+                if (pages) {
+                        for (i = 0; i < numpages; i++) {
+                                if (pages[i]) {
+                                        unlock_page(pages[i]);
+                                        page_cache_release(pages[i]);
+                                }
+                        }
+                }
+                numpages = 0;
+        }
+
+        *num = numpages;
+
+        return ret;
+}
+
+/*
+ * Zero the area past i_size but still within an allocated
+ * cluster. This avoids exposing nonzero data on subsequent file
+ * extends.
+ *
+ * We need to call this before i_size is updated on the inode because
+ * otherwise block_write_full_page() will skip writeout of pages past
+ * i_size. The new_i_size parameter is passed for this reason.
+ */
+int ocfs2_zero_tail_for_truncate(struct inode *inode, handle_t *handle,
+                                 u64 new_i_size)
+{
+        int ret, numpages;
+        struct page **pages = NULL;
+        u64 phys;
+
+        /*
+         * File systems which don't support sparse files zero on every
+         * extend.
+         */
+        if (!ocfs2_sparse_alloc(OCFS2_SB(inode->i_sb)))
+                return 0;
+
+        pages = kcalloc(ocfs2_pages_per_cluster(inode->i_sb),
+                        sizeof(struct page *), GFP_NOFS);
+        if (pages == NULL) {
+                ret = -ENOMEM;
+                mlog_errno(ret);
+                goto out;
+        }
+
+        ret = ocfs2_grab_eof_pages(inode, new_i_size, pages, &numpages, &phys);
+        if (ret) {
+                mlog_errno(ret);
+                goto out;
+        }
+
+        /*
+         * Truncate on an i_size boundary - nothing more to do.
+         */
+        if (numpages == 0)
+                goto out;
+
+        ocfs2_zero_cluster_pages(inode, new_i_size, pages, numpages, phys,
+                                 handle);
+
+        /*
+         * Initiate writeout of the pages we zero'd here. We don't
+         * wait on them - the truncate_inode_pages() call later will
+         * do that for us.
+         */
+        ret = filemap_fdatawrite(inode->i_mapping);
+        if (ret)
+                mlog_errno(ret);
+
+out:
+        if (pages)
+                kfree(pages);
+
+        return ret;
+}
+
 /*
  * It is expected, that by the time you call this function,
  * inode->i_size and fe->i_size have been adjusted.
diff --git a/fs/ocfs2/alloc.h b/fs/ocfs2/alloc.h
index bff2a162b030..3cb39cd5e478 100644
--- a/fs/ocfs2/alloc.h
+++ b/fs/ocfs2/alloc.h
@@ -71,6 +71,8 @@ struct ocfs2_truncate_context {
         struct buffer_head *tc_last_eb_bh;
 };
 
+int ocfs2_zero_tail_for_truncate(struct inode *inode, handle_t *handle,
+                                 u64 new_i_size);
 int ocfs2_prepare_truncate(struct ocfs2_super *osb,
                            struct inode *inode,
                            struct buffer_head *fe_bh,
diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index acf8f0006725..605c82a93f01 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -308,13 +308,13 @@ int ocfs2_prepare_write_nolock(struct inode *inode, struct page *page,
  * functionality yet, but IMHO it's better to cut and paste the whole
  * thing so we can avoid introducing our own bugs (and easily pick up
  * their fixes when they happen) --Mark */
-static int walk_page_buffers(   handle_t *handle,
-                                struct buffer_head *head,
-                                unsigned from,
-                                unsigned to,
-                                int *partial,
-                                int (*fn)(      handle_t *handle,
-                                                struct buffer_head *bh))
+int walk_page_buffers(  handle_t *handle,
+                        struct buffer_head *head,
+                        unsigned from,
+                        unsigned to,
+                        int *partial,
+                        int (*fn)(      handle_t *handle,
+                                        struct buffer_head *bh))
 {
         struct buffer_head *bh;
         unsigned block_start, block_end;
@@ -654,9 +654,9 @@ static void ocfs2_clear_page_regions(struct page *page,
  *
  * This will also skip zeroing, which is handled externally.
  */
-static int ocfs2_map_page_blocks(struct page *page, u64 *p_blkno,
-                                 struct inode *inode, unsigned int from,
-                                 unsigned int to, int new)
+int ocfs2_map_page_blocks(struct page *page, u64 *p_blkno,
+                          struct inode *inode, unsigned int from,
+                          unsigned int to, int new)
 {
         int ret = 0;
         struct buffer_head *head, *bh, *wait[2], **wait_bh = wait;
@@ -675,8 +675,7 @@ static int ocfs2_map_page_blocks(struct page *page, u64 *p_blkno,
                  * Ignore blocks outside of our i/o range -
                  * they may belong to unallocated clusters.
                  */
-                if (block_start >= to ||
-                    (block_start + bsize) <= from) {
+                if (block_start >= to || block_end <= from) {
                         if (PageUptodate(page))
                                 set_buffer_uptodate(bh);
                         continue;
@@ -971,7 +970,6 @@ static ssize_t ocfs2_write(struct file *file, u32 phys, handle_t *handle,
         u64 v_blkno, p_blkno;
         struct address_space *mapping = file->f_mapping;
         struct inode *inode = mapping->host;
-        unsigned int cbits = OCFS2_SB(inode->i_sb)->s_clustersize_bits;
         unsigned long index, start;
         struct page **cpages;
 
@@ -979,13 +977,11 @@ static ssize_t ocfs2_write(struct file *file, u32 phys, handle_t *handle,
 
         /*
          * Figure out how many pages we'll be manipulating here. For
-         * non-allocating write, or any writes where cluster size is
-         * less than page size, we only need one page. Otherwise,
-         * allocating writes of cluster size larger than page size
-         * need cluster size pages.
+         * non allocating write, we just change the one
+         * page. Otherwise, we'll need a whole clusters worth.
          */
-        if (new && !wc->w_large_pages)
-                numpages = (1 << cbits) / PAGE_SIZE;
+        if (new)
+                numpages = ocfs2_pages_per_cluster(inode->i_sb);
 
         cpages = kzalloc(sizeof(*cpages) * numpages, GFP_NOFS);
         if (!cpages) {
diff --git a/fs/ocfs2/aops.h b/fs/ocfs2/aops.h
index eeb2c42483e8..7d94071f0ab7 100644
--- a/fs/ocfs2/aops.h
+++ b/fs/ocfs2/aops.h
@@ -30,6 +30,18 @@ handle_t *ocfs2_start_walk_page_trans(struct inode *inode,
                                                          unsigned from,
                                                          unsigned to);
 
+int ocfs2_map_page_blocks(struct page *page, u64 *p_blkno,
+                          struct inode *inode, unsigned int from,
+                          unsigned int to, int new);
+
+int walk_page_buffers(  handle_t *handle,
+                        struct buffer_head *head,
+                        unsigned from,
+                        unsigned to,
+                        int *partial,
+                        int (*fn)(      handle_t *handle,
+                                        struct buffer_head *bh));
+
 struct ocfs2_write_ctxt;
 typedef int (ocfs2_page_writer)(struct inode *, struct ocfs2_write_ctxt *,
                                 u64 *, unsigned int *, unsigned int *);
diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 667e5a869bf5..5fd49ec169dc 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -262,6 +262,7 @@ static int ocfs2_orphan_for_truncate(struct ocfs2_super *osb,
 {
         int status;
         handle_t *handle;
+        struct ocfs2_dinode *di;
 
         mlog_entry_void();
 
@@ -275,12 +276,39 @@ static int ocfs2_orphan_for_truncate(struct ocfs2_super *osb,
                 goto out;
         }
 
-        status = ocfs2_set_inode_size(handle, inode, fe_bh, new_i_size);
+        status = ocfs2_journal_access(handle, inode, fe_bh,
+                                      OCFS2_JOURNAL_ACCESS_WRITE);
+        if (status < 0) {
+                mlog_errno(status);
+                goto out_commit;
+        }
+
+        /*
+         * Do this before setting i_size.
+         */
+        status = ocfs2_zero_tail_for_truncate(inode, handle, new_i_size);
+        if (status) {
+                mlog_errno(status);
+                goto out_commit;
+        }
+
+        i_size_write(inode, new_i_size);
+        inode->i_blocks = ocfs2_align_bytes_to_sectors(new_i_size);
+        inode->i_ctime = inode->i_mtime = CURRENT_TIME;
+
+        di = (struct ocfs2_dinode *) fe_bh->b_data;
+        di->i_size = cpu_to_le64(new_i_size);
+        di->i_ctime = di->i_mtime = cpu_to_le64(inode->i_ctime.tv_sec);
+        di->i_ctime_nsec = di->i_mtime_nsec = cpu_to_le32(inode->i_ctime.tv_nsec);
+
+        status = ocfs2_journal_dirty(handle, fe_bh);
         if (status < 0)
                 mlog_errno(status);
 
+out_commit:
         ocfs2_commit_trans(osb, handle);
 out:
+
         mlog_exit(status);
         return status;
 }
@@ -343,7 +371,6 @@ static int ocfs2_truncate_file(struct inode *inode,
                 mlog_errno(status);
                 goto bail;
         }
-        ocfs2_data_unlock(inode, 1);
 
         /* alright, we're going to need to do a full blown alloc size
          * change. Orphan the inode so that recovery can complete the
@@ -352,22 +379,25 @@ static int ocfs2_truncate_file(struct inode *inode,
         status = ocfs2_orphan_for_truncate(osb, inode, di_bh, new_i_size);
         if (status < 0) {
                 mlog_errno(status);
-                goto bail;
+                goto bail_unlock_data;
         }
 
         status = ocfs2_prepare_truncate(osb, inode, di_bh, &tc);
         if (status < 0) {
                 mlog_errno(status);
-                goto bail;
+                goto bail_unlock_data;
         }
 
         status = ocfs2_commit_truncate(osb, inode, di_bh, tc);
         if (status < 0) {
                 mlog_errno(status);
-                goto bail;
+                goto bail_unlock_data;
         }
 
         /* TODO: orphan dir cleanup here. */
+bail_unlock_data:
+        ocfs2_data_unlock(inode, 1);
+
 bail:
 
         mlog_exit(status);
diff --git a/fs/ocfs2/inode.c b/fs/ocfs2/inode.c
index 0bd86a137591..78c99b5050df 100644
--- a/fs/ocfs2/inode.c
+++ b/fs/ocfs2/inode.c
@@ -489,12 +489,38 @@ static int ocfs2_truncate_for_delete(struct ocfs2_super *osb,
         int status = 0;
         struct ocfs2_truncate_context *tc = NULL;
         struct ocfs2_dinode *fe;
+        handle_t *handle = NULL;
 
         mlog_entry_void();
 
         fe = (struct ocfs2_dinode *) fe_bh->b_data;
 
         if (fe->i_clusters) {
+                handle = ocfs2_start_trans(osb, OCFS2_INODE_UPDATE_CREDITS);
+                if (IS_ERR(handle)) {
+                        status = PTR_ERR(handle);
+                        mlog_errno(status);
+                        goto out;
+                }
+
+                status = ocfs2_journal_access(handle, inode, fe_bh,
+                                              OCFS2_JOURNAL_ACCESS_WRITE);
+                if (status < 0) {
+                        mlog_errno(status);
+                        goto out;
+                }
+
+                i_size_write(inode, 0);
+
+                status = ocfs2_mark_inode_dirty(handle, inode, fe_bh);
+                if (status < 0) {
+                        mlog_errno(status);
+                        goto out;
+                }
+
+                ocfs2_commit_trans(osb, handle);
+                handle = NULL;
+
                 status = ocfs2_prepare_truncate(osb, inode, fe_bh, &tc);
                 if (status < 0) {
                         mlog_errno(status);
@@ -507,8 +533,10 @@ static int ocfs2_truncate_for_delete(struct ocfs2_super *osb,
                         goto out;
                 }
         }
-out:
 
+out:
+        if (handle)
+                ocfs2_commit_trans(osb, handle);
         mlog_exit(status);
         return status;
 }
diff --git a/fs/ocfs2/ocfs2.h b/fs/ocfs2/ocfs2.h
index 2699f7cac21a..82cc92dcf8a6 100644
--- a/fs/ocfs2/ocfs2.h
+++ b/fs/ocfs2/ocfs2.h
@@ -495,6 +495,17 @@ static inline unsigned long ocfs2_align_clusters_to_page_index(struct super_bloc
         return index;
 }
 
+static inline unsigned int ocfs2_pages_per_cluster(struct super_block *sb)
+{
+        unsigned int cbits = OCFS2_SB(sb)->s_clustersize_bits;
+        unsigned int pages_per_cluster = 1;
+
+        if (PAGE_CACHE_SHIFT < cbits)
+                pages_per_cluster = 1 << (cbits - PAGE_CACHE_SHIFT);
+
+        return pages_per_cluster;
+}
+
 #define ocfs2_set_bit ext2_set_bit
 #define ocfs2_clear_bit ext2_clear_bit
 #define ocfs2_test_bit ext2_test_bit