NTFS: Fix a mount time deadlock.

Big thanks go to Mathias Kolehmainen for reporting the bug, providing
debug output and testing the patches I sent him to get it working.

The fix was to stop calling ntfs_attr_set() at mount time as that causes
balance_dirty_pages_ratelimited() to be called which on systems with
little memory actually tries to go and balance the dirty pages which tries
to take the s_umount semaphore but because we are still in fill_super()
across which the VFS holds s_umount for writing this results in a
deadlock.

We now do the dirty work by hand by submitting individual buffers.  This
has the annoying "feature" that mounting can take a few seconds if the
journal is large as we have clear it all.  One day someone should improve
on this by deferring the journal clearing to a helper kernel thread so it
can be done in the background but I don't have time for this at the moment
and the current solution works fine so I am leaving it like this for now.

Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

8 files changed, 178 insertions, 52 deletions

diff --git a/fs/ntfs/ChangeLog b/fs/ntfs/ChangeLog
index af4ef808fa94..345798ebd366 100644
--- a/fs/ntfs/ChangeLog
+++ b/fs/ntfs/ChangeLog
@@ -17,6 +17,18 @@ ToDo/Notes:
           happen is unclear however so it is worth waiting until someone hits
           the problem.
 
+2.1.29 - Fix a deadlock at mount time.
+
+        - During mount the VFS holds s_umount lock on the superblock.  So when
+          we try to empty the journal $LogFile contents by calling
+          ntfs_attr_set() when the machine does not have much memory and the
+          journal is large ntfs_attr_set() results in the VM trying to balance
+          dirty pages which in turn tries to that the s_umount lock and thus we
+          get a deadlock.  The solution is to not use ntfs_attr_set() and
+          instead do the zeroing by hand at the block level rather than page
+          cache level.
+        - Fix sparse warnings.
+
 2.1.28 - Fix a deadlock.
 
         - Fix deadlock in fs/ntfs/inode.c::ntfs_put_inode().  Thanks to Sergey
diff --git a/fs/ntfs/Makefile b/fs/ntfs/Makefile
index 825508385565..58b6be992544 100644
--- a/fs/ntfs/Makefile
+++ b/fs/ntfs/Makefile
@@ -6,7 +6,7 @@ ntfs-objs := aops.o attrib.o collate.o compress.o debug.o dir.o file.o \
              index.o inode.o mft.o mst.o namei.o runlist.o super.o sysctl.o \
              unistr.o upcase.o
 
-EXTRA_CFLAGS = -DNTFS_VERSION=\"2.1.28\"
+EXTRA_CFLAGS = -DNTFS_VERSION=\"2.1.29\"
 
 ifeq ($(CONFIG_NTFS_DEBUG),y)
 EXTRA_CFLAGS += -DDEBUG
diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
index 6e5c2534f4bc..cfdc7900d271 100644
--- a/fs/ntfs/aops.c
+++ b/fs/ntfs/aops.c
@@ -2,7 +2,7 @@
  * aops.c - NTFS kernel address space operations and page cache handling.
  *          Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001-2006 Anton Altaparmakov
+ * Copyright (c) 2001-2007 Anton Altaparmakov
  * Copyright (c) 2002 Richard Russon
  *
  * This program/include file is free software; you can redistribute it and/or
@@ -396,7 +396,7 @@ static int ntfs_readpage(struct file *file, struct page *page)
         loff_t i_size;
         struct inode *vi;
         ntfs_inode *ni, *base_ni;
-        u8 *kaddr;
+        u8 *addr;
         ntfs_attr_search_ctx *ctx;
         MFT_RECORD *mrec;
         unsigned long flags;
@@ -491,15 +491,15 @@ retry_readpage:
                 /* Race with shrinking truncate. */
                 attr_len = i_size;
         }
-        kaddr = kmap_atomic(page, KM_USER0);
+        addr = kmap_atomic(page, KM_USER0);
         /* Copy the data to the page. */
-        memcpy(kaddr, (u8*)ctx->attr +
+        memcpy(addr, (u8*)ctx->attr +
                         le16_to_cpu(ctx->attr->data.resident.value_offset),
                         attr_len);
         /* Zero the remainder of the page. */
-        memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
+        memset(addr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
         flush_dcache_page(page);
-        kunmap_atomic(kaddr, KM_USER0);
+        kunmap_atomic(addr, KM_USER0);
 put_unm_err_out:
         ntfs_attr_put_search_ctx(ctx);
 unm_err_out:
@@ -1344,7 +1344,7 @@ static int ntfs_writepage(struct page *page, struct writeback_control *wbc)
         loff_t i_size;
         struct inode *vi = page->mapping->host;
         ntfs_inode *base_ni = NULL, *ni = NTFS_I(vi);
-        char *kaddr;
+        char *addr;
         ntfs_attr_search_ctx *ctx = NULL;
         MFT_RECORD *m = NULL;
         u32 attr_len;
@@ -1484,14 +1484,14 @@ retry_writepage:
                 /* Shrinking cannot fail. */
                 BUG_ON(err);
         }
-        kaddr = kmap_atomic(page, KM_USER0);
+        addr = kmap_atomic(page, KM_USER0);
         /* Copy the data from the page to the mft record. */
         memcpy((u8*)ctx->attr +
                         le16_to_cpu(ctx->attr->data.resident.value_offset),
-                        kaddr, attr_len);
+                        addr, attr_len);
         /* Zero out of bounds area in the page cache page. */
-        memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
-        kunmap_atomic(kaddr, KM_USER0);
+        memset(addr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
+        kunmap_atomic(addr, KM_USER0);
         flush_dcache_page(page);
         flush_dcache_mft_record_page(ctx->ntfs_ino);
         /* We are done with the page. */
diff --git a/fs/ntfs/attrib.c b/fs/ntfs/attrib.c
index 1c08fefe487a..92dabdcf2b80 100644
--- a/fs/ntfs/attrib.c
+++ b/fs/ntfs/attrib.c
@@ -1,7 +1,7 @@
 /**
  * attrib.c - NTFS attribute operations.  Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001-2006 Anton Altaparmakov
+ * Copyright (c) 2001-2007 Anton Altaparmakov
  * Copyright (c) 2002 Richard Russon
  *
  * This program/include file is free software; you can redistribute it and/or
@@ -2500,7 +2500,7 @@ int ntfs_attr_set(ntfs_inode *ni, const s64 ofs, const s64 cnt, const u8 val)
         struct page *page;
         u8 *kaddr;
         pgoff_t idx, end;
-        unsigned int start_ofs, end_ofs, size;
+        unsigned start_ofs, end_ofs, size;
 
         ntfs_debug("Entering for ofs 0x%llx, cnt 0x%llx, val 0x%hx.",
                         (long long)ofs, (long long)cnt, val);
@@ -2548,6 +2548,8 @@ int ntfs_attr_set(ntfs_inode *ni, const s64 ofs, const s64 cnt, const u8 val)
                 kunmap_atomic(kaddr, KM_USER0);
                 set_page_dirty(page);
                 page_cache_release(page);
+                balance_dirty_pages_ratelimited(mapping);
+                cond_resched();
                 if (idx == end)
                         goto done;
                 idx++;
@@ -2604,6 +2606,8 @@ int ntfs_attr_set(ntfs_inode *ni, const s64 ofs, const s64 cnt, const u8 val)
                 kunmap_atomic(kaddr, KM_USER0);
                 set_page_dirty(page);
                 page_cache_release(page);
+                balance_dirty_pages_ratelimited(mapping);
+                cond_resched();
         }
 done:
         ntfs_debug("Done.");
diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index ffcc504a1667..c814204d4ea0 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -1,7 +1,7 @@
 /*
  * file.c - NTFS kernel file operations.  Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001-2006 Anton Altaparmakov
+ * Copyright (c) 2001-2007 Anton Altaparmakov
  *
  * This program/include file is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as published
@@ -26,7 +26,6 @@
 #include <linux/swap.h>
 #include <linux/uio.h>
 #include <linux/writeback.h>
-#include <linux/sched.h>
 
 #include <asm/page.h>
 #include <asm/uaccess.h>
@@ -362,7 +361,7 @@ static inline void ntfs_fault_in_pages_readable(const char __user *uaddr,
         volatile char c;
 
         /* Set @end to the first byte outside the last page we care about. */
-        end = (const char __user*)PAGE_ALIGN((ptrdiff_t __user)uaddr + bytes);
+        end = (const char __user*)PAGE_ALIGN((unsigned long)uaddr + bytes);
 
         while (!__get_user(c, uaddr) && (uaddr += PAGE_SIZE, uaddr < end))
                 ;
@@ -532,7 +531,8 @@ static int ntfs_prepare_pages_for_non_resident_write(struct page **pages,
         blocksize_bits = vol->sb->s_blocksize_bits;
         u = 0;
         do {
-                struct page *page = pages[u];
+                page = pages[u];
+                BUG_ON(!page);
                 /*
                  * create_empty_buffers() will create uptodate/dirty buffers if
                  * the page is uptodate/dirty.
@@ -1291,7 +1291,7 @@ static inline size_t ntfs_copy_from_user(struct page **pages,
                 size_t bytes)
 {
         struct page **last_page = pages + nr_pages;
-        char *kaddr;
+        char *addr;
         size_t total = 0;
         unsigned len;
         int left;
@@ -1300,13 +1300,13 @@ static inline size_t ntfs_copy_from_user(struct page **pages,
                 len = PAGE_CACHE_SIZE - ofs;
                 if (len > bytes)
                         len = bytes;
-                kaddr = kmap_atomic(*pages, KM_USER0);
-                left = __copy_from_user_inatomic(kaddr + ofs, buf, len);
-                kunmap_atomic(kaddr, KM_USER0);
+                addr = kmap_atomic(*pages, KM_USER0);
+                left = __copy_from_user_inatomic(addr + ofs, buf, len);
+                kunmap_atomic(addr, KM_USER0);
                 if (unlikely(left)) {
                         /* Do it the slow way. */
-                        kaddr = kmap(*pages);
-                        left = __copy_from_user(kaddr + ofs, buf, len);
+                        addr = kmap(*pages);
+                        left = __copy_from_user(addr + ofs, buf, len);
                         kunmap(*pages);
                         if (unlikely(left))
                                 goto err_out;
@@ -1408,26 +1408,26 @@ static inline size_t ntfs_copy_from_user_iovec(struct page **pages,
                 size_t *iov_ofs, size_t bytes)
 {
         struct page **last_page = pages + nr_pages;
-        char *kaddr;
+        char *addr;
         size_t copied, len, total = 0;
 
         do {
                 len = PAGE_CACHE_SIZE - ofs;
                 if (len > bytes)
                         len = bytes;
-                kaddr = kmap_atomic(*pages, KM_USER0);
-                copied = __ntfs_copy_from_user_iovec_inatomic(kaddr + ofs,
+                addr = kmap_atomic(*pages, KM_USER0);
+                copied = __ntfs_copy_from_user_iovec_inatomic(addr + ofs,
                                 *iov, *iov_ofs, len);
-                kunmap_atomic(kaddr, KM_USER0);
+                kunmap_atomic(addr, KM_USER0);
                 if (unlikely(copied != len)) {
                         /* Do it the slow way. */
-                        kaddr = kmap(*pages);
-                        copied = __ntfs_copy_from_user_iovec_inatomic(kaddr + ofs,
+                        addr = kmap(*pages);
+                        copied = __ntfs_copy_from_user_iovec_inatomic(addr + ofs,
                                         *iov, *iov_ofs, len);
                         /*
                          * Zero the rest of the target like __copy_from_user().
                          */
-                        memset(kaddr + ofs + copied, 0, len - copied);
+                        memset(addr + ofs + copied, 0, len - copied);
                         kunmap(*pages);
                         if (unlikely(copied != len))
                                 goto err_out;
@@ -1735,8 +1735,6 @@ static int ntfs_commit_pages_after_write(struct page **pages,
         read_unlock_irqrestore(&ni->size_lock, flags);
         BUG_ON(initialized_size != i_size);
         if (end > initialized_size) {
-                unsigned long flags;
-
                 write_lock_irqsave(&ni->size_lock, flags);
                 ni->initialized_size = end;
                 i_size_write(vi, end);
diff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c
index b532a730cec2..e9da092e2772 100644
--- a/fs/ntfs/inode.c
+++ b/fs/ntfs/inode.c
@@ -34,7 +34,6 @@
 #include "dir.h"
 #include "debug.h"
 #include "inode.h"
-#include "attrib.h"
 #include "lcnalloc.h"
 #include "malloc.h"
 #include "mft.h"
@@ -2500,8 +2499,6 @@ retry_truncate:
         /* Resize the attribute record to best fit the new attribute size. */
         if (new_size < vol->mft_record_size &&
                         !ntfs_resident_attr_value_resize(m, a, new_size)) {
-                unsigned long flags;
-
                 /* The resize succeeded! */
                 flush_dcache_mft_record_page(ctx->ntfs_ino);
                 mark_mft_record_dirty(ctx->ntfs_ino);
diff --git a/fs/ntfs/logfile.c b/fs/ntfs/logfile.c
index acfed325f4ec..d7932e95b1fd 100644
--- a/fs/ntfs/logfile.c
+++ b/fs/ntfs/logfile.c
@@ -1,7 +1,7 @@
 /*
  * logfile.c - NTFS kernel journal handling. Part of the Linux-NTFS project.
  *
- * Copyright (c) 2002-2005 Anton Altaparmakov
+ * Copyright (c) 2002-2007 Anton Altaparmakov
  *
  * This program/include file is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as published
@@ -724,24 +724,139 @@ bool ntfs_is_logfile_clean(struct inode *log_vi, const RESTART_PAGE_HEADER *rp)
  */
 bool ntfs_empty_logfile(struct inode *log_vi)
 {
-        ntfs_volume *vol = NTFS_SB(log_vi->i_sb);
+        VCN vcn, end_vcn;
+        ntfs_inode *log_ni = NTFS_I(log_vi);
+        ntfs_volume *vol = log_ni->vol;
+        struct super_block *sb = vol->sb;
+        runlist_element *rl;
+        unsigned long flags;
+        unsigned block_size, block_size_bits;
+        int err;
+        bool should_wait = true;
 
         ntfs_debug("Entering.");
-        if (!NVolLogFileEmpty(vol)) {
-                int err;
-                
-                err = ntfs_attr_set(NTFS_I(log_vi), 0, i_size_read(log_vi),
-                                0xff);
-                if (unlikely(err)) {
-                        ntfs_error(vol->sb, "Failed to fill $LogFile with "
-                                        "0xff bytes (error code %i).", err);
-                        return false;
-                }
-                /* Set the flag so we do not have to do it again on remount. */
-                NVolSetLogFileEmpty(vol);
+        if (NVolLogFileEmpty(vol)) {
+                ntfs_debug("Done.");
+                return true;
         }
+        /*
+         * We cannot use ntfs_attr_set() because we may be still in the middle
+         * of a mount operation.  Thus we do the emptying by hand by first
+         * zapping the page cache pages for the $LogFile/$DATA attribute and
+         * then emptying each of the buffers in each of the clusters specified
+         * by the runlist by hand.
+         */
+        block_size = sb->s_blocksize;
+        block_size_bits = sb->s_blocksize_bits;
+        vcn = 0;
+        read_lock_irqsave(&log_ni->size_lock, flags);
+        end_vcn = (log_ni->initialized_size + vol->cluster_size_mask) >>
+                        vol->cluster_size_bits;
+        read_unlock_irqrestore(&log_ni->size_lock, flags);
+        truncate_inode_pages(log_vi->i_mapping, 0);
+        down_write(&log_ni->runlist.lock);
+        rl = log_ni->runlist.rl;
+        if (unlikely(!rl || vcn < rl->vcn || !rl->length)) {
+map_vcn:
+                err = ntfs_map_runlist_nolock(log_ni, vcn, NULL);
+                if (err) {
+                        ntfs_error(sb, "Failed to map runlist fragment (error "
+                                        "%d).", -err);
+                        goto err;
+                }
+                rl = log_ni->runlist.rl;
+                BUG_ON(!rl || vcn < rl->vcn || !rl->length);
+        }
+        /* Seek to the runlist element containing @vcn. */
+        while (rl->length && vcn >= rl[1].vcn)
+                rl++;
+        do {
+                LCN lcn;
+                sector_t block, end_block;
+                s64 len;
+
+                /*
+                 * If this run is not mapped map it now and start again as the
+                 * runlist will have been updated.
+                 */
+                lcn = rl->lcn;
+                if (unlikely(lcn == LCN_RL_NOT_MAPPED)) {
+                        vcn = rl->vcn;
+                        goto map_vcn;
+                }
+                /* If this run is not valid abort with an error. */
+                if (unlikely(!rl->length || lcn < LCN_HOLE))
+                        goto rl_err;
+                /* Skip holes. */
+                if (lcn == LCN_HOLE)
+                        continue;
+                block = lcn << vol->cluster_size_bits >> block_size_bits;
+                len = rl->length;
+                if (rl[1].vcn > end_vcn)
+                        len = end_vcn - rl->vcn;
+                end_block = (lcn + len) << vol->cluster_size_bits >>
+                                block_size_bits;
+                /* Iterate over the blocks in the run and empty them. */
+                do {
+                        struct buffer_head *bh;
+
+                        /* Obtain the buffer, possibly not uptodate. */
+                        bh = sb_getblk(sb, block);
+                        BUG_ON(!bh);
+                        /* Setup buffer i/o submission. */
+                        lock_buffer(bh);
+                        bh->b_end_io = end_buffer_write_sync;
+                        get_bh(bh);
+                        /* Set the entire contents of the buffer to 0xff. */
+                        memset(bh->b_data, -1, block_size);
+                        if (!buffer_uptodate(bh))
+                                set_buffer_uptodate(bh);
+                        if (buffer_dirty(bh))
+                                clear_buffer_dirty(bh);
+                        /*
+                         * Submit the buffer and wait for i/o to complete but
+                         * only for the first buffer so we do not miss really
+                         * serious i/o errors.  Once the first buffer has
+                         * completed ignore errors afterwards as we can assume
+                         * that if one buffer worked all of them will work.
+                         */
+                        submit_bh(WRITE, bh);
+                        if (should_wait) {
+                                should_wait = false;
+                                wait_on_buffer(bh);
+                                if (unlikely(!buffer_uptodate(bh)))
+                                        goto io_err;
+                        }
+                        brelse(bh);
+                } while (++block < end_block);
+        } while ((++rl)->vcn < end_vcn);
+        up_write(&log_ni->runlist.lock);
+        /*
+         * Zap the pages again just in case any got instantiated whilst we were
+         * emptying the blocks by hand.  FIXME: We may not have completed
+         * writing to all the buffer heads yet so this may happen too early.
+         * We really should use a kernel thread to do the emptying
+         * asynchronously and then we can also set the volume dirty and output
+         * an error message if emptying should fail.
+         */
+        truncate_inode_pages(log_vi->i_mapping, 0);
+        /* Set the flag so we do not have to do it again on remount. */
+        NVolSetLogFileEmpty(vol);
         ntfs_debug("Done.");
         return true;
+io_err:
+        ntfs_error(sb, "Failed to write buffer.  Unmount and run chkdsk.");
+        goto dirty_err;
+rl_err:
+        ntfs_error(sb, "Runlist is corrupt.  Unmount and run chkdsk.");
+dirty_err:
+        NVolSetErrors(vol);
+        err = -EIO;
+err:
+        up_write(&log_ni->runlist.lock);
+        ntfs_error(sb, "Failed to fill $LogFile with 0xff bytes (error %d).",
+                        -err);
+        return false;
 }
 
 #endif /* NTFS_RW */
diff --git a/fs/ntfs/runlist.c b/fs/ntfs/runlist.c
index 9afd72c7ad0d..56a9a6d25a2a 100644
--- a/fs/ntfs/runlist.c
+++ b/fs/ntfs/runlist.c
@@ -1,7 +1,7 @@
 /**
  * runlist.c - NTFS runlist handling code.  Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001-2005 Anton Altaparmakov
+ * Copyright (c) 2001-2007 Anton Altaparmakov
  * Copyright (c) 2002-2005 Richard Russon
  *
  * This program/include file is free software; you can redistribute it and/or
@@ -1714,7 +1714,7 @@ extend_hole:
                                         sizeof(*rl));
                 /* Adjust the beginning of the tail if necessary. */
                 if (end > rl->vcn) {
-                        s64 delta = end - rl->vcn;
+                        delta = end - rl->vcn;
                         rl->vcn = end;
                         rl->length -= delta;
                         /* Only adjust the lcn if it is real. */