> > In f2fs_precache_extents(), For large files, It requires reading many
> > node blocks. Instead of reading each node block with synchronous I/O,
> > this patch applies readahead so that node blocks can be fetched in
> > advance.
> >
> > It reduces the overhead of repeated sync reads and improves efficiency
> > when precaching extents of large files.
> >
> > I created a file with the same largest extent and executed the test.
> > For this experiment, I set the file's largest extent with an offset of
> > 0 and a size of 1GB. I configured the remaining area with 100MB extents.
> >
> > 5GB test file:
> > dd if=/dev/urandom of=test1 bs=1m count=5120 cp test1 test2 fsync
> > test1 dd if=test1 of=test2 bs=1m skip=1024 seek=1024 count=100
> > conv=notrunc dd if=test1 of=test2 bs=1m skip=1224 seek=1224 count=100
> > conv=notrunc ...
> > dd if=test1 of=test2 bs=1m skip=5024 seek=5024 count=100 conv=notrunc
> > reboot
> >
> > I also created 10GB and 20GB files with large extents using the same
> > method.
> >
> > ioctl(F2FS_IOC_PRECACHE_EXTENTS) test results are as follows:
> > +-----------+---------+---------+-----------+
> > | File size | Before | After | Reduction |
> > +-----------+---------+---------+-----------+
> > | 5GB | 101.8ms | 72.1ms | 29.2% |
> > | 10GB | 222.9ms | 149.5ms | 32.9% |
> > | 20GB | 446.2ms | 276.3ms | 38.1% |
> > +-----------+---------+---------+-----------+
> > Tested on a 256GB mobile device with an SM8750 chipset.
> >
> > Reviewed-by: Sungjong Seo <sj1557....@samsung.com>
> > Reviewed-by: Sunmin Jeong <s_min.je...@samsung.com>
> > Signed-off-by: Yunji Kang <yunji0.k...@samsung.com>
> > ---
> > fs/f2fs/data.c | 3 +++
> > fs/f2fs/f2fs.h | 1 +
> > fs/f2fs/node.c | 4 +++-
> > 3 files changed, 7 insertions(+), 1 deletion(-)
> >
> > diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index
> > 7961e0ddfca3..ab3117e3b24a 100644
> > --- a/fs/f2fs/data.c
> > +++ b/fs/f2fs/data.c
> > @@ -1572,6 +1572,9 @@ int f2fs_map_blocks(struct inode *inode, struct
> f2fs_map_blocks *map, int flag)
> > pgofs = (pgoff_t)map->m_lblk;
> > end = pgofs + maxblocks;
> >
> > + if (flag == F2FS_GET_BLOCK_PRECACHE)
> > + mode = LOOKUP_NODE_PRECACHE;
> > +
> > next_dnode:
> > if (map->m_may_create) {
> > if (f2fs_lfs_mode(sbi))
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h index
> > 9d3bc9633c1d..3ce41528d48e 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -651,6 +651,7 @@ enum {
> > * look up a node with readahead called
> > * by get_data_block.
> > */
> > + LOOKUP_NODE_PRECACHE, /* look up a node for
> F2FS_GET_BLOCK_PRECACHE */
> > };
> >
> > #define DEFAULT_RETRY_IO_COUNT 8 /* maximum retry read IO or
> > flush
> count */
> > diff --git a/fs/f2fs/node.c b/fs/f2fs/node.c index
> > 4254db453b2d..50be167e5c59 100644
> > --- a/fs/f2fs/node.c
> > +++ b/fs/f2fs/node.c
> > @@ -860,7 +860,9 @@ int f2fs_get_dnode_of_data(struct dnode_of_data *dn,
> pgoff_t index, int mode)
> > set_nid(parent, offset[i - 1], nids[i], i == 1);
> > f2fs_alloc_nid_done(sbi, nids[i]);
> > done = true;
> > - } else if (mode == LOOKUP_NODE_RA && i == level && level > 1)
> {
> > + } else if ((mode == LOOKUP_NODE_RA ||
>
> Does this change the logic for mode = LOOKUP_NODE_RA?
>
> Not sure, do you mean this?
>
> if ((i == level && level > 1) &&
> (mode == LOOKUP_NODE_RA ||
> (mode == LOOKUP_NODE_PRECACHE &&
> offset[i - 1] % MAX_RA_NODE == 0)))
>
> Thanks,
>
> > + (mode == LOOKUP_NODE_PRECACHE && offset[i - 1] %
> MAX_RA_NODE == 0))
> > + && i == level && level > 1) {
> > nfolio[i] = f2fs_get_node_folio_ra(parent, offset[i -
> 1]);
> > if (IS_ERR(nfolio[i])) {
> > err = PTR_ERR(nfolio[i]);
I think the code has the same meaning.
The version you wrote looks more readable, so would it be okay if I change the
patch with your code?
Also, I did not change the logic for mode = LOOKUP_NODE_RA; I only added a
condition for when readahead is performed.
Thanks.
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