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author | Anton Altaparmakov <aia21@cantab.net> | 2005-09-19 09:41:39 +0100 |
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committer | Anton Altaparmakov <aia21@cantab.net> | 2005-09-19 09:41:39 +0100 |
commit | f6098cf449b81c14a51e48dd22ae47d03126a1de (patch) | |
tree | 89532dea05312fc70248842cd416aeb38fefb8b5 /fs/ntfs/aops.c | |
parent | 4e64c88693fde1b1cbaa4cfecad43a0c3fad354e (diff) | |
download | linux-f6098cf449b81c14a51e48dd22ae47d03126a1de.tar.bz2 |
NTFS: Fix ntfs_{read,write}page() to cope with concurrent truncates better.
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
Diffstat (limited to 'fs/ntfs/aops.c')
-rw-r--r-- | fs/ntfs/aops.c | 110 |
1 files changed, 74 insertions, 36 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); |