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-rw-r--r--include/sys/zfs_znode.h1
-rw-r--r--module/zfs/zfs_vnops.c171
-rw-r--r--module/zfs/zpl_file.c177
3 files changed, 245 insertions, 104 deletions
diff --git a/include/sys/zfs_znode.h b/include/sys/zfs_znode.h
index 53bd18109..9d12a118e 100644
--- a/include/sys/zfs_znode.h
+++ b/include/sys/zfs_znode.h
@@ -210,6 +210,7 @@ typedef struct znode {
sa_handle_t *z_sa_hdl; /* handle to sa data */
boolean_t z_is_sa; /* are we native sa? */
boolean_t z_is_zvol; /* are we used by the zvol */
+ boolean_t z_is_mapped; /* are we mmap'ed */
struct inode z_inode; /* generic vfs inode */
} znode_t;
diff --git a/module/zfs/zfs_vnops.c b/module/zfs/zfs_vnops.c
index a8019ba5c..30b30891b 100644
--- a/module/zfs/zfs_vnops.c
+++ b/module/zfs/zfs_vnops.c
@@ -163,32 +163,7 @@
* return (error); // done, report error
*/
-#if defined(_KERNEL) && defined(HAVE_MMAP)
-/*
- * Utility functions to map and unmap a single physical page. These
- * are used to manage the mappable copies of ZFS file data, and therefore
- * do not update ref/mod bits.
- */
-caddr_t
-zfs_map_page(page_t *pp, enum seg_rw rw)
-{
- if (kpm_enable)
- return (hat_kpm_mapin(pp, 0));
- ASSERT(rw == S_READ || rw == S_WRITE);
- return (ppmapin(pp, PROT_READ | ((rw == S_WRITE) ? PROT_WRITE : 0),
- (caddr_t)-1));
-}
-
-void
-zfs_unmap_page(page_t *pp, caddr_t addr)
-{
- if (kpm_enable) {
- hat_kpm_mapout(pp, 0, addr);
- } else {
- ppmapout(addr);
- }
-}
-
+#if defined(_KERNEL)
/*
* When a file is memory mapped, we must keep the IO data synchronized
* between the DMU cache and the memory mapped pages. What this means:
@@ -197,25 +172,39 @@ zfs_unmap_page(page_t *pp, caddr_t addr)
* the page and the dmu buffer.
*/
static void
-update_pages(struct inode *ip, int64_t start, int len, objset_t *os,
- uint64_t oid)
+update_pages(struct inode *ip, int64_t start, int len,
+ objset_t *os, uint64_t oid)
{
+ struct address_space *mp = ip->i_mapping;
+ struct page *pp;
+ uint64_t nbytes;
int64_t off;
+ void *pb;
- off = start & PAGEOFFSET;
- for (start &= PAGEMASK; len > 0; start += PAGESIZE) {
- page_t *pp;
- uint64_t nbytes = MIN(PAGESIZE - off, len);
+ off = start & (PAGE_CACHE_SIZE-1);
+ for (start &= PAGE_CACHE_MASK; len > 0; start += PAGE_CACHE_SIZE) {
+ nbytes = MIN(PAGE_CACHE_SIZE - off, len);
- if (pp = page_lookup(ip, start, SE_SHARED)) {
- caddr_t va;
+ pp = find_lock_page(mp, start >> PAGE_CACHE_SHIFT);
+ if (pp) {
+ if (mapping_writably_mapped(mp))
+ flush_dcache_page(pp);
- va = zfs_map_page(pp, S_WRITE);
- (void) dmu_read(os, oid, start+off, nbytes, va+off,
+ pb = kmap(pp);
+ (void) dmu_read(os, oid, start+off, nbytes, pb+off,
DMU_READ_PREFETCH);
- zfs_unmap_page(pp, va);
- page_unlock(pp);
+ kunmap(pp);
+
+ if (mapping_writably_mapped(mp))
+ flush_dcache_page(pp);
+
+ mark_page_accessed(pp);
+ SetPageUptodate(pp);
+ ClearPageError(pp);
+ unlock_page(pp);
+ page_cache_release(pp);
}
+
len -= nbytes;
off = 0;
}
@@ -234,28 +223,39 @@ update_pages(struct inode *ip, int64_t start, int len, objset_t *os,
static int
mappedread(struct inode *ip, int nbytes, uio_t *uio)
{
+ struct address_space *mp = ip->i_mapping;
+ struct page *pp;
znode_t *zp = ITOZ(ip);
objset_t *os = ITOZSB(ip)->z_os;
int64_t start, off;
+ uint64_t bytes;
int len = nbytes;
int error = 0;
+ void *pb;
start = uio->uio_loffset;
- off = start & PAGEOFFSET;
- for (start &= PAGEMASK; len > 0; start += PAGESIZE) {
- page_t *pp;
- uint64_t bytes = MIN(PAGESIZE - off, len);
-
- if (pp = page_lookup(ip, start, SE_SHARED)) {
- caddr_t va;
-
- va = zfs_map_page(pp, S_READ);
- error = uiomove(va + off, bytes, UIO_READ, uio);
- zfs_unmap_page(pp, va);
- page_unlock(pp);
+ off = start & (PAGE_CACHE_SIZE-1);
+ for (start &= PAGE_CACHE_MASK; len > 0; start += PAGE_CACHE_SIZE) {
+ bytes = MIN(PAGE_CACHE_SIZE - off, len);
+
+ pp = find_lock_page(mp, start >> PAGE_CACHE_SHIFT);
+ if (pp) {
+ ASSERT(PageUptodate(pp));
+
+ pb = kmap(pp);
+ error = uiomove(pb + off, bytes, UIO_READ, uio);
+ kunmap(pp);
+
+ if (mapping_writably_mapped(mp))
+ flush_dcache_page(pp);
+
+ mark_page_accessed(pp);
+ unlock_page(pp);
+ page_cache_release(pp);
} else {
error = dmu_read_uio(os, zp->z_id, uio, bytes);
}
+
len -= bytes;
off = 0;
if (error)
@@ -263,7 +263,7 @@ mappedread(struct inode *ip, int nbytes, uio_t *uio)
}
return (error);
}
-#endif /* _KERNEL && HAVE_MMAP */
+#endif /* _KERNEL */
offset_t zfs_read_chunk_size = 1024 * 1024; /* Tunable */
@@ -273,7 +273,8 @@ offset_t zfs_read_chunk_size = 1024 * 1024; /* Tunable */
* IN: ip - inode of file to be read from.
* uio - structure supplying read location, range info,
* and return buffer.
- * ioflag - SYNC flags; used to provide FRSYNC semantics.
+ * ioflag - FSYNC flags; used to provide FRSYNC semantics.
+ * O_DIRECT flag; used to bypass page cache.
* cr - credentials of caller.
*
* OUT: uio - updated offset and range, buffer filled.
@@ -394,15 +395,11 @@ zfs_read(struct inode *ip, uio_t *uio, int ioflag, cred_t *cr)
nbytes = MIN(n, zfs_read_chunk_size -
P2PHASE(uio->uio_loffset, zfs_read_chunk_size));
-/* XXX: Drop this, ARC update handled by zpl layer */
-#ifdef HAVE_MMAP
- if (vn_has_cached_data(ip))
+ if (zp->z_is_mapped && !(ioflag & O_DIRECT))
error = mappedread(ip, nbytes, uio);
else
error = dmu_read_uio(os, zp->z_id, uio, nbytes);
-#else
- error = dmu_read_uio(os, zp->z_id, uio, nbytes);
-#endif /* HAVE_MMAP */
+
if (error) {
/* convert checksum errors into IO errors */
if (error == ECKSUM)
@@ -429,6 +426,7 @@ EXPORT_SYMBOL(zfs_read);
* uio - structure supplying write location, range info,
* and data buffer.
* ioflag - FAPPEND flag set if in append mode.
+ * O_DIRECT flag; used to bypass page cache.
* cr - credentials of caller.
*
* OUT: uio - updated offset and range.
@@ -700,13 +698,9 @@ again:
ASSERT(tx_bytes <= uio->uio_resid);
uioskip(uio, tx_bytes);
}
-/* XXX: Drop this, ARC update handled by zpl layer */
-#ifdef HAVE_MMAP
- if (tx_bytes && vn_has_cached_data(ip)) {
- update_pages(ip, woff,
- tx_bytes, zsb->z_os, zp->z_id);
- }
-#endif /* HAVE_MMAP */
+
+ if (tx_bytes && zp->z_is_mapped && !(ioflag & O_DIRECT))
+ update_pages(ip, woff, tx_bytes, zsb->z_os, zp->z_id);
/*
* If we made no progress, we're done. If we made even
@@ -3392,6 +3386,7 @@ top:
}
EXPORT_SYMBOL(zfs_link);
+#ifdef HAVE_MMAP
/*
* zfs_null_putapage() is used when the file system has been force
* unmounted. It just drops the pages.
@@ -3627,48 +3622,30 @@ out:
ZFS_EXIT(zfsvfs);
return (error);
}
+#endif /* HAVE_MMAP */
/*ARGSUSED*/
void
-zfs_inactive(vnode_t *vp, cred_t *cr, caller_context_t *ct)
+zfs_inactive(struct inode *ip)
{
- znode_t *zp = VTOZ(vp);
- zfsvfs_t *zfsvfs = zp->z_zfsvfs;
+ znode_t *zp = ITOZ(ip);
+ zfs_sb_t *zsb = ITOZSB(ip);
int error;
- rw_enter(&zfsvfs->z_teardown_inactive_lock, RW_READER);
- if (zp->z_sa_hdl == NULL) {
- /*
- * The fs has been unmounted, or we did a
- * suspend/resume and this file no longer exists.
- */
- if (vn_has_cached_data(vp)) {
- (void) pvn_vplist_dirty(vp, 0, zfs_null_putapage,
- B_INVAL, cr);
- }
+ truncate_inode_pages(&ip->i_data, 0);
- mutex_enter(&zp->z_lock);
- mutex_enter(&vp->v_lock);
- ASSERT(vp->v_count == 1);
- vp->v_count = 0;
- mutex_exit(&vp->v_lock);
- mutex_exit(&zp->z_lock);
- rw_exit(&zfsvfs->z_teardown_inactive_lock);
- zfs_znode_free(zp);
- return;
- }
+#ifdef HAVE_SNAPSHOT
+ /* Early return for snapshot inode? */
+#endif /* HAVE_SNAPSHOT */
- /*
- * Attempt to push any data in the page cache. If this fails
- * we will get kicked out later in zfs_zinactive().
- */
- if (vn_has_cached_data(vp)) {
- (void) pvn_vplist_dirty(vp, 0, zfs_putapage, B_INVAL|B_ASYNC,
- cr);
+ rw_enter(&zsb->z_teardown_inactive_lock, RW_READER);
+ if (zp->z_sa_hdl == NULL) {
+ rw_exit(&zsb->z_teardown_inactive_lock);
+ return;
}
if (zp->z_atime_dirty && zp->z_unlinked == 0) {
- dmu_tx_t *tx = dmu_tx_create(zfsvfs->z_os);
+ dmu_tx_t *tx = dmu_tx_create(zsb->z_os);
dmu_tx_hold_sa(tx, zp->z_sa_hdl, B_FALSE);
zfs_sa_upgrade_txholds(tx, zp);
@@ -3712,6 +3689,7 @@ zfs_seek(struct inode *ip, offset_t ooff, offset_t *noffp,
}
EXPORT_SYMBOL(zfs_seek);
+#ifdef HAVE_MMAP
/*
* Pre-filter the generic locking function to trap attempts to place
* a mandatory lock on a memory mapped file.
@@ -4056,6 +4034,7 @@ zfs_delmap(vnode_t *vp, offset_t off, struct as *as, caddr_t addr,
return (0);
}
+#endif /* HAVE_MMAP */
/*
* convoff - converts the given data (start, whence) to the
diff --git a/module/zfs/zpl_file.c b/module/zfs/zpl_file.c
index 41901bb6c..585f971e8 100644
--- a/module/zfs/zpl_file.c
+++ b/module/zfs/zpl_file.c
@@ -145,24 +145,185 @@ zpl_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
return (wrote);
}
+/*
+ * It's worth taking a moment to describe how mmap is implemented
+ * for zfs because it differs considerably from other Linux filesystems.
+ * However, this issue is handled the same way under OpenSolaris.
+ *
+ * The issue is that by design zfs bypasses the Linux page cache and
+ * leaves all caching up to the ARC. This has been shown to work
+ * well for the common read(2)/write(2) case. However, mmap(2)
+ * is problem because it relies on being tightly integrated with the
+ * page cache. To handle this we cache mmap'ed files twice, once in
+ * the ARC and a second time in the page cache. The code is careful
+ * to keep both copies synchronized.
+ *
+ * When a file with an mmap'ed region is written to using write(2)
+ * both the data in the ARC and existing pages in the page cache
+ * are updated. For a read(2) data will be read first from the page
+ * cache then the ARC if needed. Neither a write(2) or read(2) will
+ * will ever result in new pages being added to the page cache.
+ *
+ * New pages are added to the page cache only via .readpage() which
+ * is called when the vfs needs to read a page off disk to back the
+ * virtual memory region. These pages may be modified without
+ * notifying the ARC and will be written out periodically via
+ * .writepage(). This will occur due to either a sync or the usual
+ * page aging behavior. Note because a read(2) of a mmap'ed file
+ * will always check the page cache first even when the ARC is out
+ * of date correct data will still be returned.
+ *
+ * While this implementation ensures correct behavior it does have
+ * have some drawbacks. The most obvious of which is that it
+ * increases the required memory footprint when access mmap'ed
+ * files. It also adds additional complexity to the code keeping
+ * both caches synchronized.
+ *
+ * Longer term it may be possible to cleanly resolve this wart by
+ * mapping page cache pages directly on to the ARC buffers. The
+ * Linux address space operations are flexible enough to allow
+ * selection of which pages back a particular index. The trick
+ * would be working out the details of which subsystem is in
+ * charge, the ARC, the page cache, or both. It may also prove
+ * helpful to move the ARC buffers to a scatter-gather lists
+ * rather than a vmalloc'ed region.
+ */
+static int
+zpl_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+ znode_t *zp = ITOZ(filp->f_mapping->host);
+ int error;
+
+ error = generic_file_mmap(filp, vma);
+ if (error)
+ return (error);
+
+ mutex_enter(&zp->z_lock);
+ zp->z_is_mapped = 1;
+ mutex_exit(&zp->z_lock);
+
+ return (error);
+}
+
+/*
+ * Populate a page with data for the Linux page cache. This function is
+ * only used to support mmap(2). There will be an identical copy of the
+ * data in the ARC which is kept up to date via .write() and .writepage().
+ *
+ * Current this function relies on zpl_read_common() and the O_DIRECT
+ * flag to read in a page. This works but the more correct way is to
+ * update zfs_fillpage() to be Linux friendly and use that interface.
+ */
+static int
+zpl_readpage(struct file *filp, struct page *pp)
+{
+ struct inode *ip;
+ loff_t off, i_size;
+ size_t len, wrote;
+ cred_t *cr;
+ void *pb;
+ int error = 0;
+
+ ASSERT(PageLocked(pp));
+ ip = pp->mapping->host;
+ off = page_offset(pp);
+ i_size = i_size_read(ip);
+ ASSERT3S(off, <, i_size);
+
+ cr = (cred_t *)get_current_cred();
+ len = MIN(PAGE_CACHE_SIZE, i_size - off);
+
+ pb = kmap(pp);
+
+ /* O_DIRECT is passed to bypass the page cache and avoid deadlock. */
+ wrote = zpl_read_common(ip, pb, len, off, UIO_SYSSPACE, O_DIRECT, cr);
+ if (wrote != len)
+ error = -EIO;
+
+ if (!error && (len < PAGE_CACHE_SIZE))
+ memset(pb + len, 0, PAGE_CACHE_SIZE - len);
+
+ kunmap(pp);
+ put_cred(cr);
+
+ if (error) {
+ SetPageError(pp);
+ ClearPageUptodate(pp);
+ } else {
+ ClearPageError(pp);
+ SetPageUptodate(pp);
+ flush_dcache_page(pp);
+ }
+
+ unlock_page(pp);
+
+ return (error);
+}
+
+/*
+ * Write out dirty pages to the ARC, this function is only required to
+ * support mmap(2). Mapped pages may be dirtied by memory operations
+ * which never call .write(). These dirty pages are kept in sync with
+ * the ARC buffers via this hook.
+ *
+ * Currently this function relies on zpl_write_common() and the O_DIRECT
+ * flag to push out the page. This works but the more correct way is
+ * to update zfs_putapage() to be Linux friendly and use that interface.
+ */
+static int
+zpl_writepage(struct page *pp, struct writeback_control *wbc)
+{
+ struct inode *ip;
+ loff_t off, i_size;
+ size_t len, read;
+ cred_t *cr;
+ void *pb;
+ int error = 0;
+
+ ASSERT(PageLocked(pp));
+ ip = pp->mapping->host;
+ off = page_offset(pp);
+ i_size = i_size_read(ip);
+
+ cr = (cred_t *)get_current_cred();
+ len = MIN(PAGE_CACHE_SIZE, i_size - off);
+
+ pb = kmap(pp);
+
+ /* O_DIRECT is passed to bypass the page cache and avoid deadlock. */
+ read = zpl_write_common(ip, pb, len, off, UIO_SYSSPACE, O_DIRECT, cr);
+ if (read != len)
+ error = -EIO;
+
+ kunmap(pp);
+ put_cred(cr);
+
+ if (error) {
+ SetPageError(pp);
+ ClearPageUptodate(pp);
+ } else {
+ ClearPageError(pp);
+ SetPageUptodate(pp);
+ }
+
+ unlock_page(pp);
+
+ return (error);
+}
+
const struct address_space_operations zpl_address_space_operations = {
-#if 0
.readpage = zpl_readpage,
.writepage = zpl_writepage,
- .direct_IO = zpl_direct_IO,
-#endif
};
const struct file_operations zpl_file_operations = {
.open = generic_file_open,
.llseek = generic_file_llseek,
- .read = zpl_read, /* do_sync_read */
- .write = zpl_write, /* do_sync_write */
+ .read = zpl_read,
+ .write = zpl_write,
.readdir = zpl_readdir,
- .mmap = generic_file_mmap,
+ .mmap = zpl_mmap,
.fsync = zpl_fsync,
- .aio_read = NULL, /* generic_file_aio_read */
- .aio_write = NULL, /* generic_file_aio_write */
};
const struct file_operations zpl_dir_file_operations = {
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-28 03:53:31 +0000