diff --git a/fs/erofs/Kconfig b/fs/erofs/Kconfig
index 2dfc313588d2..37495e95a78d 100644
--- a/fs/erofs/Kconfig
+++ b/fs/erofs/Kconfig
@@ -132,11 +132,13 @@ config EROFS_FS_ZIP_LZMA
 	  Say N if you want to disable LZMA compression support.
 
 config EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS
-	int "EROFS LZMA default maximum decompression streams"
+	int "EROFS LZMA default maximum decompression streams" if SMP
 	depends on EROFS_FS_ZIP_LZMA
 	range 1 NR_CPUS if SMP
 	range 1 1 if !SMP
-	default 16
+	default 16 if SMP && NR_CPUS >= 16
+	default NR_CPUS if SMP
+	default 1
 	help
 	  By default EROFS allocates one LZMA decompression stream per CPU.
 	  Each stream can hold a dictionary of up to 8 MiB taken from the
@@ -144,7 +146,7 @@ config EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS
 	  of memory.  This caps the default; the lzma_streams module parameter
 	  still overrides it.
 
-	  If unsure, keep the default of 16.
+	  If unsure, keep the suggested default (16 or lower).
 
 config EROFS_FS_ZIP_DEFLATE
 	bool "EROFS DEFLATE compressed data support"
diff --git a/fs/erofs/data.c b/fs/erofs/data.c
index 20962f8b60a8..0885b1f2fc92 100644
--- a/fs/erofs/data.c
+++ b/fs/erofs/data.c
@@ -497,7 +497,7 @@ static int erofs_file_mmap_prepare(struct vm_area_desc *desc)
 #define erofs_file_mmap_prepare	generic_file_readonly_mmap_prepare
 #endif
 
-static loff_t erofs_file_llseek(struct file *file, loff_t offset, int whence)
+loff_t erofs_file_llseek(struct file *file, loff_t offset, int whence)
 {
 	struct inode *inode = file->f_mapping->host;
 	const struct iomap_ops *ops = &erofs_iomap_ops;
diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
index 9b7370f0f3df..65974e57aebf 100644
--- a/fs/erofs/internal.h
+++ b/fs/erofs/internal.h
@@ -415,6 +415,7 @@ void *erofs_read_metabuf(struct erofs_buf *buf, struct super_block *sb,
 int erofs_map_dev(struct super_block *sb, struct erofs_map_dev *dev);
 int erofs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 		 u64 start, u64 len);
+loff_t erofs_file_llseek(struct file *file, loff_t offset, int whence);
 int erofs_map_blocks(struct inode *inode, struct erofs_map_blocks *map);
 void erofs_onlinefolio_init(struct folio *folio);
 void erofs_onlinefolio_split(struct folio *folio);
diff --git a/fs/erofs/ishare.c b/fs/erofs/ishare.c
index fa7d4112dec5..a1cf2aff8d32 100644
--- a/fs/erofs/ishare.c
+++ b/fs/erofs/ishare.c
@@ -54,6 +54,7 @@ bool erofs_ishare_fill_inode(struct inode *inode)
 		si->i_mapping->a_ops = aops;
 		si->i_mode = 0444 | S_IFREG;
 		si->i_size = inode->i_size;
+		mapping_set_large_folios(si->i_mapping);
 		unlock_new_inode(si);
 	} else {
 		kfree(fp.opaque);
@@ -148,6 +149,13 @@ static int erofs_ishare_mmap(struct file *file, struct vm_area_struct *vma)
 	return generic_file_readonly_mmap(file, vma);
 }
 
+static ssize_t erofs_ishare_splice_read(struct file *in, loff_t *ppos,
+					struct pipe_inode_info *pipe,
+					size_t len, unsigned int flags)
+{
+	return filemap_splice_read(in->private_data, ppos, pipe, len, flags);
+}
+
 static int erofs_ishare_fadvise(struct file *file, loff_t offset,
 				loff_t len, int advice)
 {
@@ -156,12 +164,12 @@ static int erofs_ishare_fadvise(struct file *file, loff_t offset,
 
 const struct file_operations erofs_ishare_fops = {
 	.open		= erofs_ishare_file_open,
-	.llseek		= generic_file_llseek,
+	.llseek		= erofs_file_llseek,
 	.read_iter	= erofs_ishare_file_read_iter,
 	.mmap		= erofs_ishare_mmap,
 	.release	= erofs_ishare_file_release,
 	.get_unmapped_area = thp_get_unmapped_area,
-	.splice_read	= filemap_splice_read,
+	.splice_read	= erofs_ishare_splice_read,
 	.fadvise	= erofs_ishare_fadvise,
 };
 
diff --git a/fs/erofs/zutil.c b/fs/erofs/zutil.c
index a0ce9226bc02..960cfe86eeb6 100644
--- a/fs/erofs/zutil.c
+++ b/fs/erofs/zutil.c
@@ -70,15 +70,15 @@ int z_erofs_gbuf_growsize(unsigned int nrpages)
 	void *ptr, *old_ptr;
 	int last, i, j;
 
-	mutex_lock(&gbuf_resize_mutex);
+	guard(mutex)(&gbuf_resize_mutex);
 	/* avoid shrinking gbufs, since no idea how many fses rely on */
-	if (nrpages <= z_erofs_gbuf_nrpages) {
-		mutex_unlock(&gbuf_resize_mutex);
+	if (nrpages <= z_erofs_gbuf_nrpages)
 		return 0;
-	}
 
 	for (i = 0; i < z_erofs_gbuf_count; ++i) {
 		gbuf = &z_erofs_gbufpool[i];
+		if (gbuf->nrpages >= nrpages)
+			continue;
 		tmp_pages = kzalloc_objs(*tmp_pages, nrpages);
 		if (!tmp_pages)
 			goto out;
@@ -87,8 +87,7 @@ int z_erofs_gbuf_growsize(unsigned int nrpages)
 			tmp_pages[j] = gbuf->pages[j];
 		do {
 			last = j;
-			j = alloc_pages_bulk(GFP_KERNEL, nrpages,
-					     tmp_pages);
+			j = alloc_pages_bulk(GFP_KERNEL, nrpages, tmp_pages);
 			if (last == j)
 				goto out;
 		} while (j != nrpages);
@@ -99,24 +98,23 @@ int z_erofs_gbuf_growsize(unsigned int nrpages)
 
 		spin_lock(&gbuf->lock);
 		kfree(gbuf->pages);
-		gbuf->pages = tmp_pages;
 		old_ptr = gbuf->ptr;
+		gbuf->pages = tmp_pages;
 		gbuf->ptr = ptr;
 		gbuf->nrpages = nrpages;
 		spin_unlock(&gbuf->lock);
-		if (old_ptr)
-			vunmap(old_ptr);
+		vunmap(old_ptr);
+		tmp_pages = NULL;
 	}
 	z_erofs_gbuf_nrpages = nrpages;
 out:
-	if (i < z_erofs_gbuf_count && tmp_pages) {
+	if (unlikely(tmp_pages)) {
 		for (j = 0; j < nrpages; ++j)
 			if (tmp_pages[j] && (j >= gbuf->nrpages ||
 					     tmp_pages[j] != gbuf->pages[j]))
 				__free_page(tmp_pages[j]);
 		kfree(tmp_pages);
 	}
-	mutex_unlock(&gbuf_resize_mutex);
 	return i < z_erofs_gbuf_count ? -ENOMEM : 0;
 }