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Added-By: Gordon Malm <gengor@gentoo.org>
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---
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From: Theodore Ts'o <tytso@mit.edu>
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Date: Thu, 26 Feb 2009 06:04:07 +0000 (-0500)
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Subject: ext4: add EXT4_IOC_ALLOC_DA_BLKS ioctl
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X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftytso%2Fext4.git;a=commitdiff_plain;h=3bf3342f394d72ed2ec7e77b5b39e1b50fad8284
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ext4: add EXT4_IOC_ALLOC_DA_BLKS ioctl
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Add an ioctl which forces all of the delay allocated blocks to be
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allocated. This also provides a function ext4_alloc_da_blocks() which
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will be used by the following commits to force files to be fully
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allocated to preserve application-expected ext3 behaviour.
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Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
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---
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diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
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index 684a063..ea51c89 100644
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--- a/fs/ext4/ext4.h
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+++ b/fs/ext4/ext4.h
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@@ -316,7 +316,9 @@ struct ext4_new_group_data {
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#define EXT4_IOC_GROUP_EXTEND _IOW('f', 7, unsigned long)
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#define EXT4_IOC_GROUP_ADD _IOW('f', 8, struct ext4_new_group_input)
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#define EXT4_IOC_MIGRATE _IO('f', 9)
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+ /* note ioctl 10 reserved for an early version of the FIEMAP ioctl */
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/* note ioctl 11 reserved for filesystem-independent FIEMAP ioctl */
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+#define EXT4_IOC_ALLOC_DA_BLKS _IO('f', 12)
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/*
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* ioctl commands in 32 bit emulation
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@@ -1093,6 +1095,7 @@ extern int ext4_can_truncate(struct inode *inode);
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extern void ext4_truncate(struct inode *);
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extern void ext4_set_inode_flags(struct inode *);
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extern void ext4_get_inode_flags(struct ext4_inode_info *);
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+extern int ext4_alloc_da_blocks(struct inode *inode);
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extern void ext4_set_aops(struct inode *inode);
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extern int ext4_writepage_trans_blocks(struct inode *);
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extern int ext4_meta_trans_blocks(struct inode *, int nrblocks, int idxblocks);
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diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
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index c67f46e..ead57ab 100644
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--- a/fs/ext4/inode.c
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+++ b/fs/ext4/inode.c
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@@ -2807,6 +2807,48 @@ out:
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return;
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}
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+/*
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+ * Force all delayed allocation blocks to be allocated for a given inode.
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+ */
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+int ext4_alloc_da_blocks(struct inode *inode)
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+{
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+ if (!EXT4_I(inode)->i_reserved_data_blocks &&
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+ !EXT4_I(inode)->i_reserved_meta_blocks)
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+ return 0;
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+
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+ /*
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+ * We do something simple for now. The filemap_flush() will
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+ * also start triggering a write of the data blocks, which is
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+ * not strictly speaking necessary (and for users of
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+ * laptop_mode, not even desirable). However, to do otherwise
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+ * would require replicating code paths in:
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+ *
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+ * ext4_da_writepages() ->
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+ * write_cache_pages() ---> (via passed in callback function)
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+ * __mpage_da_writepage() -->
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+ * mpage_add_bh_to_extent()
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+ * mpage_da_map_blocks()
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+ *
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+ * The problem is that write_cache_pages(), located in
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+ * mm/page-writeback.c, marks pages clean in preparation for
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+ * doing I/O, which is not desirable if we're not planning on
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+ * doing I/O at all.
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+ *
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+ * We could call write_cache_pages(), and then redirty all of
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+ * the pages by calling redirty_page_for_writeback() but that
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+ * would be ugly in the extreme. So instead we would need to
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+ * replicate parts of the code in the above functions,
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+ * simplifying them becuase we wouldn't actually intend to
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+ * write out the pages, but rather only collect contiguous
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+ * logical block extents, call the multi-block allocator, and
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+ * then update the buffer heads with the block allocations.
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+ *
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+ * For now, though, we'll cheat by calling filemap_flush(),
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+ * which will map the blocks, and start the I/O, but not
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+ * actually wait for the I/O to complete.
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+ */
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+ return filemap_flush(inode->i_mapping);
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+}
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/*
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* bmap() is special. It gets used by applications such as lilo and by
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diff --git a/fs/ext4/ioctl.c b/fs/ext4/ioctl.c
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index 22dd29f..91e75f7 100644
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--- a/fs/ext4/ioctl.c
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+++ b/fs/ext4/ioctl.c
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@@ -262,6 +262,20 @@ setversion_out:
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return err;
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}
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+ case EXT4_IOC_ALLOC_DA_BLKS:
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+ {
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+ int err;
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+ if (!is_owner_or_cap(inode))
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+ return -EACCES;
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+
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+ err = mnt_want_write(filp->f_path.mnt);
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+ if (err)
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+ return err;
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+ err = ext4_alloc_da_blocks(inode);
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+ mnt_drop_write(filp->f_path.mnt);
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+ return err;
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+ }
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+
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default:
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return -ENOTTY;
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}
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