On 21/09/20 11:11AM, Darrick J. Wong wrote: > On Sat, Sep 18, 2021 at 10:37:57PM +0530, riteshh wrote: > > +cc linux-ext4 > > > > [Thread]: https://lore.kernel.org/linux-xfs/163192864476.417973.143014658064006895.stgit@magnolia/T/#t > > > > On 21/09/17 06:31PM, Darrick J. Wong wrote: > > > From: Darrick J. Wong <djwong@xxxxxxxxxx> > > > > > > Implement this new fallocate mode so that persistent memory users can, > > > upon receipt of a pmem poison notification, cause the pmem to be > > > reinitialized to a known value (zero) and clear any hardware poison > > > state that might be lurking. > > > > > > Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx> > > > --- > > > fs/ext4/extents.c | 93 +++++++++++++++++++++++++++++++++++++++++++ > > > include/trace/events/ext4.h | 7 +++ > > > 2 files changed, 99 insertions(+), 1 deletion(-) > > > > > > > > > diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c > > > index c0de30f25185..c345002e2da6 100644 > > > --- a/fs/ext4/extents.c > > > +++ b/fs/ext4/extents.c > > > @@ -29,6 +29,7 @@ > > > #include <linux/fiemap.h> > > > #include <linux/backing-dev.h> > > > #include <linux/iomap.h> > > > +#include <linux/dax.h> > > > #include "ext4_jbd2.h" > > > #include "ext4_extents.h" > > > #include "xattr.h" > > > @@ -4475,6 +4476,90 @@ static int ext4_collapse_range(struct inode *inode, loff_t offset, loff_t len); > > > > > > static int ext4_insert_range(struct inode *inode, loff_t offset, loff_t len); > > > > > > +static long ext4_zeroinit_range(struct file *file, loff_t offset, loff_t len) > > > +{ > > > + struct inode *inode = file_inode(file); > > > + struct address_space *mapping = inode->i_mapping; > > > + handle_t *handle = NULL; > > > + loff_t end = offset + len; > > > + long ret; > > > + > > > + trace_ext4_zeroinit_range(inode, offset, len, > > > + FALLOC_FL_ZEROINIT_RANGE | FALLOC_FL_KEEP_SIZE); > > > + > > > + /* We don't support data=journal mode */ > > > + if (ext4_should_journal_data(inode)) > > > + return -EOPNOTSUPP; > > > + > > > + inode_lock(inode); > > > + > > > + /* > > > + * Indirect files do not support unwritten extents > > > + */ > > > + if (!(ext4_test_inode_flag(inode, EXT4_INODE_EXTENTS))) { > > > + ret = -EOPNOTSUPP; > > > + goto out_mutex; > > > + } > > > + > > > + /* Wait all existing dio workers, newcomers will block on i_mutex */ > > > + inode_dio_wait(inode); > > > + > > > + /* > > > + * Prevent page faults from reinstantiating pages we have released from > > > + * page cache. > > > + */ > > > + filemap_invalidate_lock(mapping); > > > + > > > + ret = ext4_break_layouts(inode); > > > + if (ret) > > > + goto out_mmap; > > > + > > > + /* Now release the pages and zero block aligned part of pages */ > > > + truncate_pagecache_range(inode, offset, end - 1); > > > + inode->i_mtime = inode->i_ctime = current_time(inode); > > > + > > > + if (IS_DAX(inode)) > > > + ret = dax_zeroinit_range(inode, offset, len, > > > + &ext4_iomap_report_ops); > > > + else > > > + ret = iomap_zeroout_range(inode, offset, len, > > > + &ext4_iomap_report_ops); > > > + if (ret == -ECANCELED) > > > + ret = -EOPNOTSUPP; > > > + if (ret) > > > + goto out_mmap; > > > + > > > + /* > > > + * In worst case we have to writeout two nonadjacent unwritten > > > + * blocks and update the inode > > > + */ > > > > Is this comment true? We are actually not touching IOMAP_UNWRITTEN blocks no? > > So is there any need for journal transaction for this? > > We are essentially only writing to blocks which are already allocated on disk > > and zeroing it out in both dax_zeroinit_range() and iomap_zeroinit_range(). > > Oops. Yeah, the comment is wrong. Deleted. > > > > + handle = ext4_journal_start(inode, EXT4_HT_MISC, 1); > > > > I guess credits is 1 here since only inode is getting modified. > > Yep. > > > > > > + if (IS_ERR(handle)) { > > > + ret = PTR_ERR(handle); > > > + ext4_std_error(inode->i_sb, ret); > > > + goto out_mmap; > > > + } > > > + > > > + inode->i_mtime = inode->i_ctime = current_time(inode); > > > + ret = ext4_mark_inode_dirty(handle, inode); > > > + if (unlikely(ret)) > > > + goto out_handle; > > > + ext4_fc_track_range(handle, inode, offset >> inode->i_sb->s_blocksize_bits, > > > + (offset + len - 1) >> inode->i_sb->s_blocksize_bits); > > > > I am not sure whether we need ext4_fc_track_range() here? > > We are not doing any metadata operation except maybe updating inode timestamp > > right? > > I wasn't sure what fastcommit needs to track about the range. Is it > /only/ tracking changes to the file mapping? cc'ing Harshad as well (to correct if any of below is incorrect/incomplete). I guess so yes, from reading this [1]. ext4_fc_track_range() - Track _changed_ logical block offsets inodes For only inode update, I guess fastcommit uses ext4_fc_track_inode(), which is implicit when we call ext4_mark_inode_dirty(). [1]: https://lore.kernel.org/all/20201015203802.3597742-6-harshadshirwadkar@xxxxxxxxx/ > > /me is sadly falling further and further behind on where ext4 is these > days... :/ > > > > > > + ext4_update_inode_fsync_trans(handle, inode, 1); Then do we even need above? -ritesh > > > + > > > + if (file->f_flags & O_SYNC) > > > + ext4_handle_sync(handle); > > > + > > > +out_handle: > > > + ext4_journal_stop(handle); > > > +out_mmap: > > > + filemap_invalidate_unlock(mapping); > > > +out_mutex: > > > + inode_unlock(inode); > > > + return ret; > > > +} > > > + > > > static long ext4_zero_range(struct file *file, loff_t offset, > > > loff_t len, int mode) > > > { > > > @@ -4659,7 +4744,7 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len) > > > /* Return error if mode is not supported */ > > > if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE | > > > FALLOC_FL_COLLAPSE_RANGE | FALLOC_FL_ZERO_RANGE | > > > - FALLOC_FL_INSERT_RANGE)) > > > + FALLOC_FL_INSERT_RANGE | FALLOC_FL_ZEROINIT_RANGE)) > > > return -EOPNOTSUPP; > > > > > > ext4_fc_start_update(inode); > > > @@ -4687,6 +4772,12 @@ long ext4_fallocate(struct file *file, int mode, loff_t offset, loff_t len) > > > ret = ext4_zero_range(file, offset, len, mode); > > > goto exit; > > > } > > > + > > > + if (mode & FALLOC_FL_ZEROINIT_RANGE) { > > > + ret = ext4_zeroinit_range(file, offset, len); > > > + goto exit; > > > + } > > > + > > > trace_ext4_fallocate_enter(inode, offset, len, mode); > > > lblk = offset >> blkbits; > > > > > > diff --git a/include/trace/events/ext4.h b/include/trace/events/ext4.h > > > index 0ea36b2b0662..282f1208067f 100644 > > > --- a/include/trace/events/ext4.h > > > +++ b/include/trace/events/ext4.h > > > @@ -1407,6 +1407,13 @@ DEFINE_EVENT(ext4__fallocate_mode, ext4_zero_range, > > > TP_ARGS(inode, offset, len, mode) > > > ); > > > > > > +DEFINE_EVENT(ext4__fallocate_mode, ext4_zeroinit_range, > > > + > > > + TP_PROTO(struct inode *inode, loff_t offset, loff_t len, int mode), > > > + > > > + TP_ARGS(inode, offset, len, mode) > > > +); > > > + > > > TRACE_EVENT(ext4_fallocate_exit, > > > TP_PROTO(struct inode *inode, loff_t offset, > > > unsigned int max_blocks, int ret), > > >
