btrfs: drop from __GFP_HIGHMEM all allocations

The highmem flag is used for allocating pages for compression and for
raid56 pages. The high memory makes sense on 32bit systems but is not
without problems. On 64bit system's it's just another layer of wrappers.

The time the pages are allocated for compression or raid56 is relatively
short (about a transaction commit), so the pages are not blocked
indefinitely. As the number of pages depends on the amount of data being
written/read, there's a theoretical problem. A fast device on a 32bit
system could use most of the low memory pool, while with the highmem
allocation that would not happen. This was possibly the original idea
long time ago, but nowadays we optimize for 64bit systems.

This patch removes all usage of the __GFP_HIGHMEM flag for page
allocation, the kmap/kunmap are still in place and will be removed in
followup patches. Remaining is masking out the bit in
alloc_extent_state and __lookup_free_space_inode, that can safely stay.

Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 30d82cdf128cf4037cc3d779df80939e84b92929..49fdec423092296f52165b3c091796213d0a19fc 100644 (file)
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -721,8 +721,7 @@ blk_status_t btrfs_submit_compressed_read(struct inode *inode, struct bio *bio,
                goto fail1;
 
        for (pg_index = 0; pg_index < nr_pages; pg_index++) {
-               cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS |
-                                                             __GFP_HIGHMEM);
+               cb->compressed_pages[pg_index] = alloc_page(GFP_NOFS);
                if (!cb->compressed_pages[pg_index]) {
                        faili = pg_index - 1;
                        ret = BLK_STS_RESOURCE;

diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c
index cd042c7567a4752f2103cb2d1d5a23fc578ff5b2..2bebb60c5830ada7943a8638c6986d6a04176827 100644 (file)
--- a/fs/btrfs/lzo.c
+++ b/fs/btrfs/lzo.c
@@ -146,7 +146,7 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,
         * store the size of all chunks of compressed data in
         * the first 4 bytes
         */
-       out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+       out_page = alloc_page(GFP_NOFS);
        if (out_page == NULL) {
                ret = -ENOMEM;
                goto out;
@@ -216,7 +216,7 @@ int lzo_compress_pages(struct list_head *ws, struct address_space *mapping,
                                        goto out;
                                }
 
-                               out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+                               out_page = alloc_page(GFP_NOFS);
                                if (out_page == NULL) {
                                        ret = -ENOMEM;
                                        goto out;

diff --git a/fs/btrfs/raid56.c b/fs/btrfs/raid56.c
index 244d499ebc72ca112ced4571e5ae5dc6a032169b..a40a45a007d456a4944a3498fbefa154870570a0 100644 (file)
--- a/fs/btrfs/raid56.c
+++ b/fs/btrfs/raid56.c
@@ -1035,7 +1035,7 @@ static int alloc_rbio_pages(struct btrfs_raid_bio *rbio)
        for (i = 0; i < rbio->nr_pages; i++) {
                if (rbio->stripe_pages[i])
                        continue;
-               page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+               page = alloc_page(GFP_NOFS);
                if (!page)
                        return -ENOMEM;
                rbio->stripe_pages[i] = page;
@@ -1054,7 +1054,7 @@ static int alloc_rbio_parity_pages(struct btrfs_raid_bio *rbio)
        for (; i < rbio->nr_pages; i++) {
                if (rbio->stripe_pages[i])
                        continue;
-               page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+               page = alloc_page(GFP_NOFS);
                if (!page)
                        return -ENOMEM;
                rbio->stripe_pages[i] = page;
@@ -2300,7 +2300,7 @@ static int alloc_rbio_essential_pages(struct btrfs_raid_bio *rbio)
                        if (rbio->stripe_pages[index])
                                continue;
 
-                       page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+                       page = alloc_page(GFP_NOFS);
                        if (!page)
                                return -ENOMEM;
                        rbio->stripe_pages[index] = page;
@@ -2350,14 +2350,14 @@ static noinline void finish_parity_scrub(struct btrfs_raid_bio *rbio,
        if (!need_check)
                goto writeback;
 
-       p_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+       p_page = alloc_page(GFP_NOFS);
        if (!p_page)
                goto cleanup;
        SetPageUptodate(p_page);
 
        if (has_qstripe) {
                /* RAID6, allocate and map temp space for the Q stripe */
-               q_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+               q_page = alloc_page(GFP_NOFS);
                if (!q_page) {
                        __free_page(p_page);
                        goto cleanup;

diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index c3fa7d3fa77076493d44f0a60bbce8c74f877efb..2c792bc5a9874bbf8f4b5aabcb8d885af2f78e11 100644 (file)
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -121,7 +121,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
        workspace->strm.total_in = 0;
        workspace->strm.total_out = 0;
 
-       out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+       out_page = alloc_page(GFP_NOFS);
        if (out_page == NULL) {
                ret = -ENOMEM;
                goto out;
@@ -202,7 +202,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
                                ret = -E2BIG;
                                goto out;
                        }
-                       out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+                       out_page = alloc_page(GFP_NOFS);
                        if (out_page == NULL) {
                                ret = -ENOMEM;
                                goto out;
@@ -240,7 +240,7 @@ int zlib_compress_pages(struct list_head *ws, struct address_space *mapping,
                                ret = -E2BIG;
                                goto out;
                        }
-                       out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+                       out_page = alloc_page(GFP_NOFS);
                        if (out_page == NULL) {
                                ret = -ENOMEM;
                                goto out;

diff --git a/fs/btrfs/zstd.c b/fs/btrfs/zstd.c
index 3e26b466476ab002620ac77ff185264024f41e1b..9451d2bb984ecf61ea13a2c19145da68a14a5ed3 100644 (file)
--- a/fs/btrfs/zstd.c
+++ b/fs/btrfs/zstd.c
@@ -405,7 +405,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
 
 
        /* Allocate and map in the output buffer */
-       out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+       out_page = alloc_page(GFP_NOFS);
        if (out_page == NULL) {
                ret = -ENOMEM;
                goto out;
@@ -452,7 +452,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
                                ret = -E2BIG;
                                goto out;
                        }
-                       out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+                       out_page = alloc_page(GFP_NOFS);
                        if (out_page == NULL) {
                                ret = -ENOMEM;
                                goto out;
@@ -512,7 +512,7 @@ int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
                        ret = -E2BIG;
                        goto out;
                }
-               out_page = alloc_page(GFP_NOFS | __GFP_HIGHMEM);
+               out_page = alloc_page(GFP_NOFS);
                if (out_page == NULL) {
                        ret = -ENOMEM;
                        goto out;