NTFS: Fix ntfs_{read,write}page() to cope with concurrent truncates better.

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

3 files changed, 80 insertions, 41 deletions

diff --git a/fs/ntfs/aops.c b/fs/ntfs/aops.c
index 5fd516f42eec..5e80c07c6a4d 100644
--- a/fs/ntfs/aops.c
+++ b/fs/ntfs/aops.c
@@ -59,39 +59,49 @@ static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
         unsigned long flags;
         struct buffer_head *first, *tmp;
         struct page *page;
+        struct inode *vi;
         ntfs_inode *ni;
         int page_uptodate = 1;
 
         page = bh->b_page;
-        ni = NTFS_I(page->mapping->host);
+        vi = page->mapping->host;
+        ni = NTFS_I(vi);
 
         if (likely(uptodate)) {
-                s64 file_ofs, initialized_size;
+                loff_t i_size;
+                s64 file_ofs, init_size;
 
                 set_buffer_uptodate(bh);
 
                 file_ofs = ((s64)page->index << PAGE_CACHE_SHIFT) +
                                 bh_offset(bh);
                 read_lock_irqsave(&ni->size_lock, flags);
-                initialized_size = ni->initialized_size;
+                init_size = ni->initialized_size;
+                i_size = i_size_read(vi);
                 read_unlock_irqrestore(&ni->size_lock, flags);
+                if (unlikely(init_size > i_size)) {
+                        /* Race with shrinking truncate. */
+                        init_size = i_size;
+                }
                 /* Check for the current buffer head overflowing. */
-                if (file_ofs + bh->b_size > initialized_size) {
-                        char *addr;
-                        int ofs = 0;
-
-                        if (file_ofs < initialized_size)
-                                ofs = initialized_size - file_ofs;
-                        addr = kmap_atomic(page, KM_BIO_SRC_IRQ);
-                        memset(addr + bh_offset(bh) + ofs, 0, bh->b_size - ofs);
+                if (unlikely(file_ofs + bh->b_size > init_size)) {
+                        u8 *kaddr;
+                        int ofs;
+
+                        ofs = 0;
+                        if (file_ofs < init_size)
+                                ofs = init_size - file_ofs;
+                        kaddr = kmap_atomic(page, KM_BIO_SRC_IRQ);
+                        memset(kaddr + bh_offset(bh) + ofs, 0,
+                                        bh->b_size - ofs);
+                        kunmap_atomic(kaddr, KM_BIO_SRC_IRQ);
                         flush_dcache_page(page);
-                        kunmap_atomic(addr, KM_BIO_SRC_IRQ);
                 }
         } else {
                 clear_buffer_uptodate(bh);
                 SetPageError(page);
-                ntfs_error(ni->vol->sb, "Buffer I/O error, logical block %llu.",
-                                (unsigned long long)bh->b_blocknr);
+                ntfs_error(ni->vol->sb, "Buffer I/O error, logical block "
+                                "0x%llx.", (unsigned long long)bh->b_blocknr);
         }
         first = page_buffers(page);
         local_irq_save(flags);
@@ -124,7 +134,7 @@ static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
                 if (likely(page_uptodate && !PageError(page)))
                         SetPageUptodate(page);
         } else {
-                char *addr;
+                u8 *kaddr;
                 unsigned int i, recs;
                 u32 rec_size;
 
@@ -132,12 +142,12 @@ static void ntfs_end_buffer_async_read(struct buffer_head *bh, int uptodate)
                 recs = PAGE_CACHE_SIZE / rec_size;
                 /* Should have been verified before we got here... */
                 BUG_ON(!recs);
-                addr = kmap_atomic(page, KM_BIO_SRC_IRQ);
+                kaddr = kmap_atomic(page, KM_BIO_SRC_IRQ);
                 for (i = 0; i < recs; i++)
-                        post_read_mst_fixup((NTFS_RECORD*)(addr +
+                        post_read_mst_fixup((NTFS_RECORD*)(kaddr +
                                         i * rec_size), rec_size);
+                kunmap_atomic(kaddr, KM_BIO_SRC_IRQ);
                 flush_dcache_page(page);
-                kunmap_atomic(addr, KM_BIO_SRC_IRQ);
                 if (likely(page_uptodate && !PageError(page)))
                         SetPageUptodate(page);
         }
@@ -168,8 +178,11 @@ still_busy:
  */
 static int ntfs_read_block(struct page *page)
 {
+        loff_t i_size;
         VCN vcn;
         LCN lcn;
+        s64 init_size;
+        struct inode *vi;
         ntfs_inode *ni;
         ntfs_volume *vol;
         runlist_element *rl;
@@ -180,7 +193,8 @@ static int ntfs_read_block(struct page *page)
         int i, nr;
         unsigned char blocksize_bits;
 
-        ni = NTFS_I(page->mapping->host);
+        vi = page->mapping->host;
+        ni = NTFS_I(vi);
         vol = ni->vol;
 
         /* $MFT/$DATA must have its complete runlist in memory at all times. */
@@ -199,11 +213,28 @@ static int ntfs_read_block(struct page *page)
         bh = head = page_buffers(page);
         BUG_ON(!bh);
 
+        /*
+         * We may be racing with truncate.  To avoid some of the problems we
+         * now take a snapshot of the various sizes and use those for the whole
+         * of the function.  In case of an extending truncate it just means we
+         * may leave some buffers unmapped which are now allocated.  This is
+         * not a problem since these buffers will just get mapped when a write
+         * occurs.  In case of a shrinking truncate, we will detect this later
+         * on due to the runlist being incomplete and if the page is being
+         * fully truncated, truncate will throw it away as soon as we unlock
+         * it so no need to worry what we do with it.
+         */
         iblock = (s64)page->index << (PAGE_CACHE_SHIFT - blocksize_bits);
         read_lock_irqsave(&ni->size_lock, flags);
         lblock = (ni->allocated_size + blocksize - 1) >> blocksize_bits;
-        zblock = (ni->initialized_size + blocksize - 1) >> blocksize_bits;
+        init_size = ni->initialized_size;
+        i_size = i_size_read(vi);
         read_unlock_irqrestore(&ni->size_lock, flags);
+        if (unlikely(init_size > i_size)) {
+                /* Race with shrinking truncate. */
+                init_size = i_size;
+        }
+        zblock = (init_size + blocksize - 1) >> blocksize_bits;
 
         /* Loop through all the buffers in the page. */
         rl = NULL;
@@ -366,6 +397,8 @@ handle_zblock:
  */
 static int ntfs_readpage(struct file *file, struct page *page)
 {
+        loff_t i_size;
+        struct inode *vi;
         ntfs_inode *ni, *base_ni;
         u8 *kaddr;
         ntfs_attr_search_ctx *ctx;
@@ -384,7 +417,8 @@ retry_readpage:
                 unlock_page(page);
                 return 0;
         }
-        ni = NTFS_I(page->mapping->host);
+        vi = page->mapping->host;
+        ni = NTFS_I(vi);
         /*
          * Only $DATA attributes can be encrypted and only unnamed $DATA
          * attributes can be compressed.  Index root can have the flags set but
@@ -458,7 +492,12 @@ retry_readpage:
         read_lock_irqsave(&ni->size_lock, flags);
         if (unlikely(attr_len > ni->initialized_size))
                 attr_len = ni->initialized_size;
+        i_size = i_size_read(vi);
         read_unlock_irqrestore(&ni->size_lock, flags);
+        if (unlikely(attr_len > i_size)) {
+                /* Race with shrinking truncate. */
+                attr_len = i_size;
+        }
         kaddr = kmap_atomic(page, KM_USER0);
         /* Copy the data to the page. */
         memcpy(kaddr, (u8*)ctx->attr +
@@ -1383,8 +1422,8 @@ retry_writepage:
                         unsigned int ofs = i_size & ~PAGE_CACHE_MASK;
                         kaddr = kmap_atomic(page, KM_USER0);
                         memset(kaddr + ofs, 0, PAGE_CACHE_SIZE - ofs);
-                        flush_dcache_page(page);
                         kunmap_atomic(kaddr, KM_USER0);
+                        flush_dcache_page(page);
                 }
                 /* Handle mst protected attributes. */
                 if (NInoMstProtected(ni))
@@ -1447,34 +1486,33 @@ retry_writepage:
         BUG_ON(PageWriteback(page));
         set_page_writeback(page);
         unlock_page(page);
-        /*
-         * Here, we do not need to zero the out of bounds area everytime
-         * because the below memcpy() already takes care of the
-         * mmap-at-end-of-file requirements.  If the file is converted to a
-         * non-resident one, then the code path use is switched to the
-         * non-resident one where the zeroing happens on each ntfs_writepage()
-         * invocation.
-         */
         attr_len = le32_to_cpu(ctx->attr->data.resident.value_length);
         i_size = i_size_read(vi);
         if (unlikely(attr_len > i_size)) {
+                /* Race with shrinking truncate or a failed truncate. */
                 attr_len = i_size;
-                ctx->attr->data.resident.value_length = cpu_to_le32(attr_len);
+                /*
+                 * If the truncate failed, fix it up now.  If a concurrent
+                 * truncate, we do its job, so it does not have to do anything.
+                 */
+                err = ntfs_resident_attr_value_resize(ctx->mrec, ctx->attr,
+                                attr_len);
+                /* Shrinking cannot fail. */
+                BUG_ON(err);
         }
         kaddr = 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);
-        flush_dcache_mft_record_page(ctx->ntfs_ino);
         /* Zero out of bounds area in the page cache page. */
         memset(kaddr + attr_len, 0, PAGE_CACHE_SIZE - attr_len);
-        flush_dcache_page(page);
         kunmap_atomic(kaddr, KM_USER0);
-
+        flush_dcache_mft_record_page(ctx->ntfs_ino);
+        flush_dcache_page(page);
+        /* We are done with the page. */
         end_page_writeback(page);
-
-        /* Mark the mft record dirty, so it gets written back. */
+        /* Finally, mark the mft record dirty, so it gets written back. */
         mark_mft_record_dirty(ctx->ntfs_ino);
         ntfs_attr_put_search_ctx(ctx);
         unmap_mft_record(base_ni);
diff --git a/fs/ntfs/inode.c b/fs/ntfs/inode.c
index dc4bbe3acf5c..7ec045131808 100644
--- a/fs/ntfs/inode.c
+++ b/fs/ntfs/inode.c
@@ -1166,6 +1166,8 @@ err_out:
  *
  * Return 0 on success and -errno on error.  In the error case, the inode will
  * have had make_bad_inode() executed on it.
+ *
+ * Note this cannot be called for AT_INDEX_ALLOCATION.
  */
 static int ntfs_read_locked_attr_inode(struct inode *base_vi, struct inode *vi)
 {
@@ -1242,8 +1244,8 @@ static int ntfs_read_locked_attr_inode(struct inode *base_vi, struct inode *vi)
                         }
                 }
                 /*
-                 * The encryption flag set in an index root just means to
-                 * compress all files.
+                 * The compressed/sparse flag set in an index root just means
+                 * to compress all files.
                  */
                 if (NInoMstProtected(ni) && ni->type != AT_INDEX_ROOT) {
                         ntfs_error(vi->i_sb, "Found mst protected attribute "
@@ -1319,8 +1321,7 @@ static int ntfs_read_locked_attr_inode(struct inode *base_vi, struct inode *vi)
                                         "the mapping pairs array.");
                         goto unm_err_out;
                 }
-                if ((NInoCompressed(ni) || NInoSparse(ni)) &&
-                                ni->type != AT_INDEX_ROOT) {
+                if (NInoCompressed(ni) || NInoSparse(ni)) {
                         if (a->data.non_resident.compression_unit != 4) {
                                 ntfs_error(vi->i_sb, "Found nonstandard "
                                                 "compression unit (%u instead "
diff --git a/fs/ntfs/malloc.h b/fs/ntfs/malloc.h
index 3288bcc2c4aa..006946efca8c 100644
--- a/fs/ntfs/malloc.h
+++ b/fs/ntfs/malloc.h
@@ -1,7 +1,7 @@
 /*
  * malloc.h - NTFS kernel memory handling. Part of the Linux-NTFS project.
  *
- * Copyright (c) 2001-2004 Anton Altaparmakov
+ * Copyright (c) 2001-2005 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