NTFS: Fix fs/ntfs/aops.c::ntfs_{read,write}_block() to handle the case

      where a concurrent truncate has truncated the runlist under our feet.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>

2 files changed, 42 insertions, 11 deletions

diff --git a/fs/ntfs/ChangeLog b/fs/ntfs/ChangeLog
index 10fc2385efa7..7f24cb19c69e 100644
--- a/fs/ntfs/ChangeLog
+++ b/fs/ntfs/ChangeLog
@@ -84,6 +84,8 @@ ToDo/Notes:
         - Optimize fs/ntfs/aops.c::ntfs_write_block() by extending the page
           lock protection over the buffer submission for i/o which allows the
           removal of the get_bh()/put_bh() pairs for each buffer.
+        - Fix fs/ntfs/aops.c::ntfs_{read,write}_block() to handle the case
+          where a concurrent truncate has truncated the runlist under our feet.
 
 2.1.23 - Implement extension of resident files and make writing safe as well as
          many bug fixes, cleanups, and enhancements...
diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
index 821dad7d14c8..59389a8801bc 100644
--- a/fs/ntfs/aops.c
+++ b/fs/ntfs/aops.c
@@ -204,6 +204,7 @@ static int ntfs_read_block(struct page *page)
         nr = i = 0;
         do {
                 u8 *kaddr;
+                int err;
 
                 if (unlikely(buffer_uptodate(bh)))
                         continue;
@@ -211,6 +212,7 @@ static int ntfs_read_block(struct page *page)
                         arr[nr++] = bh;
                         continue;
                 }
+                err = 0;
                 bh->b_bdev = vol->sb->s_bdev;
                 /* Is the block within the allowed limits? */
                 if (iblock < lblock) {
@@ -252,7 +254,6 @@ lock_retry_remap:
                                 goto handle_hole;
                         /* If first try and runlist unmapped, map and retry. */
                         if (!is_retry && lcn == LCN_RL_NOT_MAPPED) {
-                                int err;
                                 is_retry = TRUE;
                                 /*
                                  * Attempt to map runlist, dropping lock for
@@ -263,20 +264,30 @@ lock_retry_remap:
                                 if (likely(!err))
                                         goto lock_retry_remap;
                                 rl = NULL;
-                                lcn = err;
                         } else if (!rl)
                                 up_read(&ni->runlist.lock);
+                        /*
+                         * If buffer is outside the runlist, treat it as a
+                         * hole.  This can happen due to concurrent truncate
+                         * for example.
+                         */
+                        if (err == -ENOENT || lcn == LCN_ENOENT) {
+                                err = 0;
+                                goto handle_hole;
+                        }
                         /* Hard error, zero out region. */
+                        if (!err)
+                                err = -EIO;
                         bh->b_blocknr = -1;
                         SetPageError(page);
                         ntfs_error(vol->sb, "Failed to read from inode 0x%lx, "
                                         "attribute type 0x%x, vcn 0x%llx, "
                                         "offset 0x%x because its location on "
                                         "disk could not be determined%s "
-                                        "(error code %lli).", ni->mft_no,
+                                        "(error code %i).", ni->mft_no,
                                         ni->type, (unsigned long long)vcn,
                                         vcn_ofs, is_retry ? " even after "
-                                        "retrying" : "", (long long)lcn);
+                                        "retrying" : "", err);
                 }
                 /*
                  * Either iblock was outside lblock limits or
@@ -289,9 +300,10 @@ handle_hole:
 handle_zblock:
                 kaddr = kmap_atomic(page, KM_USER0);
                 memset(kaddr + i * blocksize, 0, blocksize);
-                flush_dcache_page(page);
                 kunmap_atomic(kaddr, KM_USER0);
-                set_buffer_uptodate(bh);
+                flush_dcache_page(page);
+                if (likely(!err))
+                        set_buffer_uptodate(bh);
         } while (i++, iblock++, (bh = bh->b_this_page) != head);
 
         /* Release the lock if we took it. */
@@ -711,20 +723,37 @@ lock_retry_remap:
                         if (likely(!err))
                                 goto lock_retry_remap;
                         rl = NULL;
-                        lcn = err;
                 } else if (!rl)
                         up_read(&ni->runlist.lock);
+                /*
+                 * If buffer is outside the runlist, truncate has cut it out
+                 * of the runlist.  Just clean and clear the buffer and set it
+                 * uptodate so it can get discarded by the VM.
+                 */
+                if (err == -ENOENT || lcn == LCN_ENOENT) {
+                        u8 *kaddr;
+
+                        bh->b_blocknr = -1;
+                        clear_buffer_dirty(bh);
+                        kaddr = kmap_atomic(page, KM_USER0);
+                        memset(kaddr + bh_offset(bh), 0, blocksize);
+                        kunmap_atomic(kaddr, KM_USER0);
+                        flush_dcache_page(page);
+                        set_buffer_uptodate(bh);
+                        err = 0;
+                        continue;
+                }
                 /* Failed to map the buffer, even after retrying. */
+                if (!err)
+                        err = -EIO;
                 bh->b_blocknr = -1;
                 ntfs_error(vol->sb, "Failed to write to inode 0x%lx, "
                                 "attribute type 0x%x, vcn 0x%llx, offset 0x%x "
                                 "because its location on disk could not be "
-                                "determined%s (error code %lli).", ni->mft_no,
+                                "determined%s (error code %i).", ni->mft_no,
                                 ni->type, (unsigned long long)vcn,
                                 vcn_ofs, is_retry ? " even after "
-                                "retrying" : "", (long long)lcn);
-                if (!err)
-                        err = -EIO;
+                                "retrying" : "", err);
                 break;
         } while (block++, (bh = bh->b_this_page) != head);