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fs/ntfs3: improve readahead for bitmap initialization and large directory scans

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Previously sequential reads operations relied solely on single-page reads,
causing the block layer to perform many synchronous I/O requests,
especially for large volumes or large directories. This patch introduces
explicit readahead via page_cache_sync_readahead() and file_ra_state to
reduce I/O latency and improve sequential throughput.

Signed-off-by: Konstantin Komarov <almaz.alexandrovich@paragon-software.com>
This commit is contained in:
Konstantin Komarov
2025-12-08 23:27:20 +03:00
parent 4248f563f0
commit 989e29450e
6 changed files with 79 additions and 25 deletions
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17
fs/ntfs3/bitmap.c
View File

@@ -508,6 +508,8 @@ static int wnd_rescan(struct wnd_bitmap *wnd)
size_t wpos, wbit, iw, vbo;
struct buffer_head *bh = NULL;
CLST lcn, clen;
struct file_ra_state *ra;
struct address_space *mapping = sb->s_bdev->bd_mapping;
wnd->uptodated = 0;
wnd->extent_max = 0;
@@ -516,6 +518,13 @@ static int wnd_rescan(struct wnd_bitmap *wnd)
vbo = 0;
/* Allocate in memory instead of stack. Not critical if failed. */
ra = kzalloc(sizeof(*ra), GFP_NOFS);
if (ra) {
file_ra_state_init(ra, mapping);
ra->ra_pages = (wnd->nbits / 8 + PAGE_SIZE - 1) >> PAGE_SHIFT;
}
for (iw = 0; iw < wnd->nwnd; iw++) {
if (iw + 1 == wnd->nwnd)
wbits = wnd->bits_last;
@@ -552,6 +561,13 @@ static int wnd_rescan(struct wnd_bitmap *wnd)
len = ((u64)clen << cluster_bits) - off;
}
if (ra) {
pgoff_t idx = lbo >> PAGE_SHIFT;
if (!ra_has_index(ra, idx))
page_cache_sync_readahead(mapping, ra, NULL,
idx, 1);
}
bh = ntfs_bread(sb, lbo >> sb->s_blocksize_bits);
if (!bh) {
err = -EIO;
@@ -638,6 +654,7 @@ static int wnd_rescan(struct wnd_bitmap *wnd)
}
out:
kfree(ra);
return err;
}

4
fs/ntfs3/dir.c
View File

@@ -487,8 +487,8 @@ static int ntfs_readdir(struct file *file, struct dir_context *ctx)
goto out;
}
err = indx_read(&ni->dir, ni, bit << ni->dir.idx2vbn_bits,
&node);
err = indx_read_ra(&ni->dir, ni, bit << ni->dir.idx2vbn_bits,
&node, &file->f_ra);
if (err)
goto out;

6
fs/ntfs3/fslog.c
View File

@@ -1074,6 +1074,8 @@ struct ntfs_log {
u32 client_undo_commit;
struct restart_info rst_info, rst_info2;
struct file_ra_state read_ahead;
};
static inline u32 lsn_to_vbo(struct ntfs_log *log, const u64 lsn)
@@ -1164,8 +1166,8 @@ static int read_log_page(struct ntfs_log *log, u32 vbo,
page_buf = page_off ? log->one_page_buf : *buffer;
err = ntfs_read_run_nb(ni->mi.sbi, &ni->file.run, page_vbo, page_buf,
log->page_size, NULL);
err = ntfs_read_run_nb_ra(ni->mi.sbi, &ni->file.run, page_vbo, page_buf,
log->page_size, NULL, &log->read_ahead);
if (err)
goto out;

29
fs/ntfs3/fsntfs.c
View File

@@ -1164,11 +1164,13 @@ struct buffer_head *ntfs_bread_run(struct ntfs_sb_info *sbi,
return ntfs_bread(sb, lbo >> sb->s_blocksize_bits);
}
int ntfs_read_run_nb(struct ntfs_sb_info *sbi, const struct runs_tree *run,
u64 vbo, void *buf, u32 bytes, struct ntfs_buffers *nb)
int ntfs_read_run_nb_ra(struct ntfs_sb_info *sbi, const struct runs_tree *run,
u64 vbo, void *buf, u32 bytes, struct ntfs_buffers *nb,
struct file_ra_state *ra)
{
int err;
struct super_block *sb = sbi->sb;
struct address_space *mapping = sb->s_bdev->bd_mapping;
u32 blocksize = sb->s_blocksize;
u8 cluster_bits = sbi->cluster_bits;
u32 off = vbo & sbi->cluster_mask;
@@ -1208,10 +1210,22 @@ int ntfs_read_run_nb(struct ntfs_sb_info *sbi, const struct runs_tree *run,
nb->bytes = bytes;
}
if (ra && !ra->ra_pages)
file_ra_state_init(ra, mapping);
for (;;) {
u32 len32 = len >= bytes ? bytes : len;
sector_t block = lbo >> sb->s_blocksize_bits;
if (ra) {
pgoff_t index = lbo >> PAGE_SHIFT;
if (!ra_has_index(ra, index)) {
page_cache_sync_readahead(mapping, ra, NULL,
index, 1);
ra->prev_pos = (loff_t)index << PAGE_SHIFT;
}
}
do {
u32 op = blocksize - off;
@@ -1282,11 +1296,11 @@ int ntfs_read_run_nb(struct ntfs_sb_info *sbi, const struct runs_tree *run,
*
* Return: < 0 if error, 0 if ok, -E_NTFS_FIXUP if need to update fixups.
*/
int ntfs_read_bh(struct ntfs_sb_info *sbi, const struct runs_tree *run, u64 vbo,
struct NTFS_RECORD_HEADER *rhdr, u32 bytes,
struct ntfs_buffers *nb)
int ntfs_read_bh_ra(struct ntfs_sb_info *sbi, const struct runs_tree *run,
u64 vbo, struct NTFS_RECORD_HEADER *rhdr, u32 bytes,
struct ntfs_buffers *nb, struct file_ra_state *ra)
{
int err = ntfs_read_run_nb(sbi, run, vbo, rhdr, bytes, nb);
int err = ntfs_read_run_nb_ra(sbi, run, vbo, rhdr, bytes, nb, ra);
if (err)
return err;
@@ -1347,8 +1361,7 @@ int ntfs_get_bh(struct ntfs_sb_info *sbi, const struct runs_tree *run, u64 vbo,
wait_on_buffer(bh);
lock_buffer(bh);
if (!buffer_uptodate(bh))
{
if (!buffer_uptodate(bh)) {
memset(bh->b_data, 0, blocksize);
set_buffer_uptodate(bh);
}

13
fs/ntfs3/index.c
View File

@@ -1026,17 +1026,18 @@ static int indx_write(struct ntfs_index *indx, struct ntfs_inode *ni,
}
/*
* indx_read
* indx_read_ra
*
* If ntfs_readdir calls this function
* inode is shared locked and no ni_lock.
* Use rw_semaphore for read/write access to alloc_run.
*/
int indx_read(struct ntfs_index *indx, struct ntfs_inode *ni, CLST vbn,
struct indx_node **node)
int indx_read_ra(struct ntfs_index *indx, struct ntfs_inode *ni, CLST vbn,
struct indx_node **node, struct file_ra_state *ra)
{
int err;
struct INDEX_BUFFER *ib;
struct ntfs_sb_info *sbi = ni->mi.sbi;
struct runs_tree *run = &indx->alloc_run;
struct rw_semaphore *lock = &indx->run_lock;
u64 vbo = (u64)vbn << indx->vbn2vbo_bits;
@@ -1062,7 +1063,7 @@ int indx_read(struct ntfs_index *indx, struct ntfs_inode *ni, CLST vbn,
}
down_read(lock);
err = ntfs_read_bh(ni->mi.sbi, run, vbo, &ib->rhdr, bytes, &in->nb);
err = ntfs_read_bh_ra(sbi, run, vbo, &ib->rhdr, bytes, &in->nb, ra);
up_read(lock);
if (!err)
goto ok;
@@ -1082,7 +1083,7 @@ int indx_read(struct ntfs_index *indx, struct ntfs_inode *ni, CLST vbn,
goto out;
down_read(lock);
err = ntfs_read_bh(ni->mi.sbi, run, vbo, &ib->rhdr, bytes, &in->nb);
err = ntfs_read_bh_ra(sbi, run, vbo, &ib->rhdr, bytes, &in->nb, ra);
up_read(lock);
if (err == -E_NTFS_FIXUP)
goto ok;
@@ -1098,7 +1099,7 @@ int indx_read(struct ntfs_index *indx, struct ntfs_inode *ni, CLST vbn,
}
if (err == -E_NTFS_FIXUP) {
ntfs_write_bh(ni->mi.sbi, &ib->rhdr, &in->nb, 0);
ntfs_write_bh(sbi, &ib->rhdr, &in->nb, 0);
err = 0;
}

35
fs/ntfs3/ntfs_fs.h
View File

@@ -625,11 +625,27 @@ int ntfs_sb_write_run(struct ntfs_sb_info *sbi, const struct runs_tree *run,
u64 vbo, const void *buf, size_t bytes, int sync);
struct buffer_head *ntfs_bread_run(struct ntfs_sb_info *sbi,
const struct runs_tree *run, u64 vbo);
int ntfs_read_run_nb(struct ntfs_sb_info *sbi, const struct runs_tree *run,
u64 vbo, void *buf, u32 bytes, struct ntfs_buffers *nb);
int ntfs_read_bh(struct ntfs_sb_info *sbi, const struct runs_tree *run, u64 vbo,
struct NTFS_RECORD_HEADER *rhdr, u32 bytes,
struct ntfs_buffers *nb);
int ntfs_read_run_nb_ra(struct ntfs_sb_info *sbi, const struct runs_tree *run,
u64 vbo, void *buf, u32 bytes, struct ntfs_buffers *nb,
struct file_ra_state *ra);
static inline int ntfs_read_run_nb(struct ntfs_sb_info *sbi,
const struct runs_tree *run, u64 vbo,
void *buf, u32 bytes,
struct ntfs_buffers *nb)
{
return ntfs_read_run_nb_ra(sbi, run, vbo, buf, bytes, nb, NULL);
}
int ntfs_read_bh_ra(struct ntfs_sb_info *sbi, const struct runs_tree *run,
u64 vbo, struct NTFS_RECORD_HEADER *rhdr, u32 bytes,
struct ntfs_buffers *nb, struct file_ra_state *ra);
static inline int ntfs_read_bh(struct ntfs_sb_info *sbi,
const struct runs_tree *run, u64 vbo,
struct NTFS_RECORD_HEADER *rhdr, u32 bytes,
struct ntfs_buffers *nb)
{
return ntfs_read_bh_ra(sbi, run, vbo, rhdr, bytes, nb, NULL);
}
int ntfs_get_bh(struct ntfs_sb_info *sbi, const struct runs_tree *run, u64 vbo,
u32 bytes, struct ntfs_buffers *nb);
int ntfs_write_bh(struct ntfs_sb_info *sbi, struct NTFS_RECORD_HEADER *rhdr,
@@ -695,8 +711,13 @@ int indx_init(struct ntfs_index *indx, struct ntfs_sb_info *sbi,
const struct ATTRIB *attr, enum index_mutex_classed type);
struct INDEX_ROOT *indx_get_root(struct ntfs_index *indx, struct ntfs_inode *ni,
struct ATTRIB **attr, struct mft_inode **mi);
int indx_read(struct ntfs_index *idx, struct ntfs_inode *ni, CLST vbn,
struct indx_node **node);
int indx_read_ra(struct ntfs_index *idx, struct ntfs_inode *ni, CLST vbn,
struct indx_node **node, struct file_ra_state *ra);
static inline int indx_read(struct ntfs_index *idx, struct ntfs_inode *ni,
CLST vbn, struct indx_node **node)
{
return indx_read_ra(idx, ni, vbn, node, NULL);
}
int indx_find(struct ntfs_index *indx, struct ntfs_inode *dir,
const struct INDEX_ROOT *root, const void *Key, size_t KeyLen,
const void *param, int *diff, struct NTFS_DE **entry,